ORIGINAL RESEARCH article

Findings from the international lucid dream induction study.

\r\nDenholm Jay Adventure-Heart*

  • School of Psychology, The University of Adelaide, North Terrace Campus, Adelaide, SA, Australia

The International Lucid Dream Induction Study (ILDIS) investigated and compared the effectiveness of five different combinations of lucid dream induction techniques including reality testing (RT), Wake Back to Bed (WBTB), the Mnemonic Induction of Lucid Dreams (MILD) technique, the Senses Initiated Lucid Dream (SSILD) technique, and a hybrid technique combining elements of both MILD and SSILD. Participants with an interest in lucid dreaming ( N = 355) completed a pre-test questionnaire and then a baseline sleep and dream recall logbook for 1 week before practicing the lucid dream induction techniques for another week. Results indicated that the MILD technique and the SSILD technique were similarly effective for inducing lucid dreams. The hybrid technique showed no advantage over MILD or SSILD. Predictors of successful lucid dream induction included superior general dream recall and the ability to fall asleep within 10 min of completing the lucid dream induction techniques. Successful lucid dream induction had no adverse effect on sleep quality. Findings indicated that the techniques were effective regardless of baseline lucid dreaming frequency or prior experience with lucid dreaming techniques. Recommendations for further research on lucid dream induction techniques are provided.

Introduction

In a lucid dream, the dreamer is aware that they are dreaming while the dream is still happening ( LaBerge, 1985 ). According to a recent meta-analysis by Saunders et al. (2016) , 55% of adults have experienced at least one lucid dream and 23% experience lucid dreams regularly (once per month or more). Recent research indicates that deliberate control is possible in approximately one third of lucid dreams ( Soffer-Dudek, 2020 ). Examples include changing location and deliberately waking up ( LaBerge and Rheingold, 1991 ; LaBerge and DeGracia, 2000 ; Love, 2013 ; Mota-Rolim et al., 2013 ). Lucid dreaming has many potential benefits and applications, such as treatment for nightmares ( Spoormaker and Van Den Bout, 2006 ; Lancee et al., 2010 ; Holzinger et al., 2015 ), improvement of physical skills and abilities through dream rehearsal ( Erlacher and Schredl, 2010 ; Stumbrys et al., 2016 ), creative problem solving ( Stumbrys and Daniels, 2010 ), and research opportunities for exploring mind-body relationships and consciousness (see Hobson, 2009 ). However, to date the effects reported in most studies have been weak and inconsistent, and more research is needed into the applications of lucid dreaming ( Baird et al., 2019 ; de Macêdo et al., 2019 ).

Many techniques exist for inducing lucid dreams (see Tholey, 1983 ; LaBerge and Rheingold, 1991 ; Stumbrys et al., 2012 ; Love, 2013 ). These techniques have been organized by Stumbrys et al. (2012) according to three broad categories. Cognitive techniques include mental exercises that increase the likelihood of lucid dreaming. The two most widely researched cognitive techniques are reality testing (RT; Tholey, 1983 ; LaBerge and Rheingold, 1991 ) and the Mnemonic Induction of Lucid Dreams (MILD) technique ( LaBerge, 1980 ; LaBerge and Rheingold, 1991 ). RT involves examining one’s environment and then performing a reliable test that differentiates between waking and dreaming, repeatedly throughout the day. The rationale is that if RT becomes habitual, it will eventually be performed while dreaming, triggering lucidity. The MILD technique involves creating a prospective memory intention to remember that one is dreaming by repeating the phrase “next time I’m dreaming, I will remember I’m dreaming” (or some variation). The MILD technique is performed during a brief awakening after 5 or so hours of sleep. Indeed, waking up after several hours of sleep for the purpose of lucid dream induction is itself a technique, known as Wake Back to Bed (WBTB; LaBerge and Rheingold, 1991 ). When successful, the MILD technique triggers lucidity during subsequent REM sleep. External stimulation techniques involve stimuli such as flashing lights presented during REM sleep that can be incorporated into dreams, serving as cues that trigger lucidity. Miscellaneous techniques include lucid dream inducing drugs and supplements (see LaBerge, 2004 ; see also Yuschak, 2006 ).

Stumbrys et al. (2012) identified 35 empirical studies on lucid dream induction techniques in a systematic review. Most (24) were field studies, with the others conducted in sleep laboratories (11). Stumbrys et al. (2012) evaluated these studies using a methodological quality checklist developed by Downs and Black (1998) and found that most (60%) were of poor methodological quality. The others were classified as moderate quality. More than half of the studies were unpublished Ph.D. dissertations or otherwise not published in peer-reviewed journals. All studies showed poor external validity. Participants were mostly university students or self-selected and highly experienced lucid dreamers. Most lucid dreaming studies are also limited by small sample sizes, lack of random allocation, failure to investigate variables that operationalize the way in which techniques were practiced (e.g., number of technique repetitions), and inconsistent operationalization of lucid dreaming rates (see Aspy et al., 2017 for a more detailed discussion). These widespread limitations are a major impediment to lucid dream research and make it difficult to compare the effectiveness of techniques across studies.

Several additional lucid dream induction studies have been published since the publication of Stumbrys et al. (2012) . Taitz (2011) found that daily RT for 2 weeks was ineffective. Poor success rates were reported in laboratory studies of external stimulation (flashing lights and vibration; Franc et al., 2014 ) and transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC) during REM sleep ( Stumbrys et al., 2013 ). Dyck et al. (2017) found that keeping a dream diary, RT, and a combined WBTB and affirmation technique were ineffective. In a study by Konkoly and Burke (2019) , 19 participants performed RT, MILD, and the Wake-Induced Lucid Dream technique (WILD). However, the authors did not provide statistics to indicate how effective this training program was except that 39 lucid dreams were reported. Saunders et al. (2017) found that a greater proportion of participants who practiced several techniques over a 12-week period (including RT, MILD and WBTB) experienced lucid dreaming compared to a control group (45 vs. 6%). However, the frequency of lucid dreaming is unclear. Kumar et al. (2018) reported a low success rate (at most 6% of days had lucid dreams) for Tholey’s combined technique, which involves regular reality tests combined with autosuggestion and intention to have a lucid dream ( Tholey, 1983 ). Sparrow et al. (2018) found that the drug Galantamine was effective for inducing lucid dreams. However, results do not permit calculation of lucid dreaming rates. LaBerge et al. (2018) found that lucid dreaming occurred on 42% of nights when participants ingested 8 mg of Galantamine in addition to practicing the MILD technique, and in most cases, using an external stimulation device (flashing light). A success rate of 14% was reported for a control condition involving the same techniques but with placebo pills.

The National Australian Lucid Dream Induction Study (NALDIS; Aspy et al., 2017 ) provided a thorough investigation into RT, MILD and WBTB using a highly diverse sample of Australian participants ( N = 169). During Week 1, participants recorded baseline dream recall rates and were then randomly allocated to one of three experimental groups for Week 2. Because RT, WBTB and MILD are often used in combination, and in the interests of identifying a maximally effective approach to lucid dream induction, an additive approach in which groups involving RT only ( RT only group), RT and WBTB ( RT + WBTB group) and RT, WBTB, and MILD ( RT + WBTB + MILD group) were compared. A significant increase in lucid dreaming was observed in the RT + WBTB + MILD group, with lucid dreaming reported on 17.4% of nights in Week 2 compared to 9.4% of nights in Week 1. No significant changes in lucid dreaming frequency were observed in the other two groups. However, although RT was ineffective when practiced in isolation, it remained uncertain whether RT contributed to the significant increase in lucid dreaming rates observed in the RT + WBTB + MILD group. This is important because RT is a burdensome practice, and if ineffective, it would be better to simply practice WBTB and MILD. Higher general dream recall was a significant predictor of lucid dreaming following practice of the MILD technique. However, the strongest predictor of lucid dreaming was the amount of time taken to fall back asleep after completing the MILD technique. Lucid dreaming was experienced on 45.8% of occasions when participants completed the MILD technique and then fell asleep within 5 min. A likely explanation is that returning to sleep quickly makes it more likely that the MILD intention will persist into REM sleep and trigger lucidity.

The biggest impediment to research into the potential benefits and applications of lucid dreaming is the lack of effective and reliable lucid dream induction techniques. Despite a reduction of research interest in lucid dream induction over the past few decades ( Stumbrys et al., 2012 ), many promising avenues for research remain. Numerous lucid dream induction techniques have been developed by lucid dreaming enthusiasts but have not been investigated scientifically. One promising example is the cognitive technique known as the Senses Initiated Lucid Dream (SSILD) technique (the double “S” in the acronym is intentional; Gary Zhang, 2013 ). The SSILD technique involves waking up after approximately 5 h of sleep (as with MILD) and then repeatedly shifting one’s attention between visual, auditory, and physical sensations before returning to sleep. The International Lucid Dream Induction Study (ILDIS) aimed to investigate the effectiveness of the SSILD technique and address unanswered questions from the NALDIS about the effectiveness of the MILD technique when practiced alone compared to when practiced in combination with RT. The ILDIS also aimed to compare two different types of RT and examine the effectiveness of a hybrid technique combining elements of both MILD and SSILD. Recruitment took place during a media release and subsequent media coverage that occurred when the NALDIS was published. The following hypotheses were tested:

• It was hypothesized that general dream recall rates would be positively correlated with lucid dreaming frequency at both pre-test and during Week 2.

• It was hypothesized that Week 2 lucid dreaming rates would be significantly higher than Week 1 lucid dreaming rates.

• It was hypothesized that lucid dreaming rates would be significantly higher when participants took 5 min or less to fall asleep after practicing lucid dreaming techniques compared to when they took more than 5 min to fall asleep.

Materials and Methods

Participants.

An initial sample of 1618 participants completed the pre-test questionnaire. A total of 843 participants continued to complete Week 1 of the study and 355 participants completed Week 2. In the final sample there were 190 (53.5%) females, 162 (45.6%) males and 3 (0.9%) “other.” Mean age was 35.3 ( SD = 12.4, range: 18–84). Most participants ( n = 255) were employed non-students (71.8%), with 69 (19.4%) students and 31 (8.7%) unemployed or retired. Just over half of participants (54.9%) reported prior experience with lucid dream induction techniques. Only six participants (1.7%) had participated in prior lucid dreaming research. Participants reported M = 1.1 lucid dreams in the month prior to commencing the study ( SD = 2.4, range: 0–28). Participants heard about the study from a wide range of sources that directed them to the present author’s website, where they could sign up to participate. Sources included: 183 (51.6%) from Facebook; 83 (23.4%) from other internet sources (e.g., email lists and social media); 40 (11.3%) from newspaper articles; 28 (7.9%) from a friend; 18 (5.1%) from radio interviews; and 3 (0.9%) from a television interview with the author. Country of residence was: 111 in United States (31.3%); 76 in Australia (21.4%); 26 in United Kingdom (7.3%); 25 in Canada (7.0%); 14 in Germany (3.9%); 9 in Mexico (2.5%); and 94 in a wide variety of other countries (26.5%). Participants were excluded from the study if they had been diagnosed with any kind of mental health disorder, sleep disorder, or neurological disorder; suspected they might have one of these disorders; were experiencing a traumatic or highly stressful life event that was interfering with their sleep; suffered from persistent insomnia or were unable to keep a regular sleep schedule; had experienced sleep paralysis more than once in the past 6 months; found it unpleasant to think about their dreams; or were under 18 years of age. No material incentive was offered. This study was granted ethics approval by the School of Psychology Human Research Ethics Subcommittee at the University of Adelaide. Participants were given an information sheet and then gave informed consent prior to participating.

Materials included a pre-test questionnaire, logbooks for Week 1 and Week 2, and technique instructions documents. All pre-test, Week 1 logbook and Week 2 logbook measures were hosted online using the survey management website Survey Monkey . Instructions were sent via email. In the present paper, pre-test variables are identified by a capital “P” and logbook variables by a capital “L.”

Pre-test Questionnaire

Participants indicated their gender, age, occupation, how they heard about the study, their country of residence, and if they had ever participated in a scientific study on lucid dreaming techniques. Retrospective general dream recall was operationalized as Dream Recall Frequency (DRF; the percentage of days on which there was dream recall) and measured by asking “How many days during the last week did you remember your dreams from the previous night?” ( P DRF ). Response options ranged from “0 days” to “7 days.” Retrospective lucid dreaming rates were operationalized as Dream Count ( L DC Lucid per month ; the number of dreams recalled over the past month) and assessed using a question adapted from Brown and Donderi (1986) Sleep and Dream Questionnaire (SDQ): “Lucid dreams are those in which a person becomes aware of the fact that he or she is dreaming while the dream is still ongoing. For example: ‘I was in England talking to my grandfather when I remembered that (in real life) he had died several years ago and that I had never been to England. I concluded that I was dreaming and decided to fly to get a bird’s eye view of the countryside…’ Please estimate the number of lucid dreams you have had in the past month.” Response options ranged from 0 to 30 or “more than 30” (scale unit = 1, range: 0–20). Participants were asked “Have you ever tried to have lucid dreams by learning and then practicing a lucid dreaming technique?” ( P Lucid tech prior ; “yes” or “no”). Participants were asked, “How often have you practiced a lucid dreaming technique recently (in the past several months)?” ( P Lucid tech freq ). Response options from Schredl (2004) widely used dream recall measure were used (0 = never; 1 = less than once a month; 2 = about once a month; 3 = two or three times a month; 4 = about once a week; 5 = several times a week; and 6 = almost every morning). Responses were converted to the approximate number of days per week using the following class means: 0 = 0; 1 = 0.125; 2 = 0.25; 3 = 0.625; 4 = 1.0; 5 = 3.5; 6 = 6.5.

Participants wrote the date for each logbook entry. This information was used to calculate the number of days taken to complete all seven logbook entries ( L Days to complete log ). The total number of logbook entries was also counted ( L Total log entries ). Participants reported whether they could recall anything specific about their dreams from the preceding night and provided brief titles for each dream they could recall. Using this information, general dream recall was operationalized as both Dream Recall Frequency ( L DRF ; the percentage of days on which there was dream recall) and Dream Count ( L DC per day ; the number of dreams recalled each day). Participants also rated how much content they could recall from each dream according to four categories, operationalizing dream recall as Dream Quantity ( L DQ ). The measure was developed by Aspy (2016) and is based on an earlier measure developed by Reed (1973) . Category ratings are converted to numerical values (“Fragmentary” = 1, “Partial” = 2, “Majority” = 4, “Whole” = 8) and summed (higher scores indicate superior dream recall). The number values 1, 2, 4, and 8 reflect the proportionate increase in dream content associated with the category labels and descriptions, based on qualitative data collected by Reed (1973) . Lucid dreaming was operationalized as DRF ( L DRF Lucid ; the percentage of mornings on which lucid dreaming was reported) using the following question: “Did you have any lucid dreams last night? (Lucid dreams are those in which a person becomes aware of the fact that he or she is dreaming while the dream is still ongoing)” (“yes” or “no”). DRF was used instead of DC because participants were unsure of how many lucid dreams they had in some cases, and in other cases lost and regained lucidity within the same dream.

Participants estimated their total time asleep ( L Time asleep ): “How much time in total do you think you spent sleeping last night? hours, minutes.” Participants rated their subjective sleep quality ( L Sleep quality ): “On a scale of 1–5, what was the overall quality of your sleep last night?” (1 = “terrible,” 2 = “poor,” 3 = “okay,” 4 = “good,” 5 = “excellent”). Participants indicated how tired they felt on waking when they were finished sleeping ( L Tiredness on waking ): “On a scale of 1–5, how tired do you feel this morning?” (1 = “not at all tired,” 2 = “slightly tired,” 3 = “somewhat tired,” 4 = “quite tired,” 5 = “very tired”). Participants indicated their level of sleep deprivation from the previous day ( L Sleep dep yesterday ): “On a scale of 1–5, how sleep deprived were you yesterday?” (1 = “not at all,” 2 = “slightly,” 3 = “somewhat,” 4 = “quite,” 5 = “very”). This measure was included to assess any potential effect of sleep deprivation on lucid dream induction, e.g., due to a REM rebound effect.

The Week 2 logbooks included additional measures related to lucid dreaming technique practice. All participants were asked “Did you turn on the light when the alarm woke you up to do the lucid dreaming technique?” ( L Light on when awoke ; “yes” or “no”); “Did you get out of bed (including if you went to the toilet) when the alarm woke you up to do the lucid dreaming technique?” ( L Out of bed when awoke ; “yes” or “no”); “How long (approximately) did you spend on doing the technique? minutes.” ( L Technique min ); “Did you fall asleep while you were still trying to do the technique?” (“yes” or “no”) ( L Asleep during technique ); and “If you answered “no” to the above question, how long (approximately) did it take for you to get to sleep after you stopped doing the technique? minutes.” ( L Min back to sleep ). Participants who practiced RT (Groups 2 and 3) were asked “How many reality tests did you perform yesterday?” (blank space provided) ( L Reality tests ). Participants in Groups 1, 2, 3, and 4 that all involved the MILD technique were asked “How many times (approx.) did you repeat “next time I’m dreaming, I will remember I’m dreaming” after the alarm woke you up?” ( L MILD phrase repetitions ). Participants in Group 5 who practiced the SSILD technique were asked “How many fast and slow cycles did you do? Fast, Slow.” ( L Fast cycles and L Slow cycles ). Participants in Group 6, which involved the hybrid MILD and SSILD technique, were asked “How many cycles did you do after the alarm woke you up?” ( L Hybrid technique cycles ).

Lucid Dream Induction Technique Documents

All participants were advised to print their lucid dream induction technique instructions, keep them beside the bed, spend a full hour familiarizing themselves with them before commencing the study, practice their techniques at least once during the day to ensure understanding, and to revise the instructions directly before bed each night. All participants were instructed to set an alarm 5 h after going to bed, to place the alarm somewhere that would require getting out of bed to turn it off, and to then practice their assigned “Nighttime Technique” when the alarm went off. Based on findings from the NALDIS, the importance of falling asleep quickly after practicing the techniques was emphasized. Participants were advised that if they were falling asleep too quickly, they could try turning the lights on for a few minutes and reading over the technique instructions to increase wakefulness. They were advised to keep the lights off, put the alarm next to their bed, and use a quieter alarm tone if they had trouble returning to sleep. All participants were given instructions on how to perform an RT if they suspected they were dreaming but were not sure. Participants were told not to practice RT during the day except for participants in Group 2 and Group 3 (see section “Group 2: MILD + WBTB + RT Breath” and section “Group 3: MILD + WBTB + RT Hands”). Participants were also given information and advice about sleep paralysis (see LaBerge and Rheingold, 1991 ; Sleep Paralysis Information Service, 2013 ; University of Waterloo, 2013 ). Instructions that were specific to each group are provided below.

Group 1: MILD + WBTB (No RT)

Participants in this group were given a “Nighttime Lucid Dreaming Technique” document that contained instructions for the MILD technique. This involved recalling a dream from directly prior to waking up (or alternatively, any other recent dream), laying down comfortably, and then repeating the phrase “next time I’m dreaming, I will remember I’m dreaming.” The importance of strong intention was emphasized. Participants were told to simultaneously visualize being back in the dream they had recalled and noticing something unusual that causes them to realize they are dreaming. They were advised to continue until they felt their intention was set.

Group 2: MILD + WBTB + RT Breath

These participants were given the same MILD instructions as Group 1. They were also provided with instructions for performing a minimum of 10 inhalation RT per day. This involves closing one’s lips and then attempting to inhale through the mouth, which is possible in dreams but not while awake (see Aspy et al., 2017 ).

Group 3: MILD + WBTB + RT Hands

This group was given a different kind of RT from Group 2, which involves attempting to push the fingers of one hand through the palm of the other. This was chosen because it is one of the most widely practiced RT. The ability to push the fingers through the palm indicates that one is dreaming. Participants were advised to also inspect their hands for anomalies during each test.

Group 4: MILD + WBTB (No RT)

Instructions for this group were the same as the instructions for Group 1, with no modifications. The decision to include a second MILD + WBTB (no RT) group in Cohort 2 was based on the fact that some participant sample characteristics changed over time during the recruitment process (see section “Preliminary Analyses”). The inclusion of a second MILD + WBTB (no RT) group in Cohort 2 permitted valid comparison of the MILD and SSILD techniques.

Group 5: SSILD + WBTB (No RT)

Instructions for the SSILD technique were designed with consultation from the creator of the technique. It was explained that the technique works by conditioning the mind and body into a subtle state that is optimized for lucid dreams to occur, and that it involves performing several “cycles” that each involve the following three steps:

Step 1. Focus on Vision : Close your eyes and focus all your attention on the darkness behind your closed eyelids. Keep your eyes completely still and totally relaxed. You might see colored dots, complex patterns, images, or maybe nothing at all. It doesn’t matter what you can or cannot see – just pay attention in a passive and relaxed manner and don’t “try” to see anything.

Step 2. Focus on Hearing : Shift all of your attention to your ears. You might be able to hear the faint sounds of traffic or the wind from outside. You might also be able to hear sounds from within you, such as your own heartbeat or a faint ringing in your ears. It doesn’t matter what, if anything, you can hear – just focus all of your attention on your hearing.

Step 3. Focus on Bodily Sensations : Shift all of your attention to sensations from your body. Feel the weight of the blanket, your heartbeat, the temperature of the air, etc. You might also notice some unusual sensations such as tingling, heaviness, lightness, spinning sensations, and so on. If this happens simply relax, observe them passively and try not to get excited.

Participants were instructed to first perform four fast cycles (2 or 3 s on each step) and then four to six slow cycles (approximately 20 s on each step). They were told not to count the number of seconds, and that it is important to complete at least four slow cycles. Participants were instructed to fall asleep as normal after completing six slow cycles.

Group 6: SSILD/MILD Hybrid + WBTB

Participants were asked to do only four to six slow cycles (no fast cycles) and to repeat the MILD phrase “next time I’m dreaming, I will remember I’m dreaming” every time they switched to a new sensory modality. The importance of strong intention was emphasized. Participants were not asked to recall dreams or do any visualization.

The ILDIS was conducted entirely via the internet, allowing people from around the world to complete the study at home. Participants were directed to a web page about the ILDIS using a URL included in a range of media items (see section “Participants”), where they read the information sheet and completed the pre-test questionnaire. Participants were sent emails with instructions and web URLs for accessing the Week 1 logbooks hosted on Survey Monkey . Participants were instructed to complete each logbook entry immediately upon waking, and to not practice any lucid dreaming techniques during Week 1. Participants were given instructions on how to improve their dream recall during both Week 1 and Week 2. Upon completing Day 7 of the Week 1 logbook, participants were sent further instructions, lucid dream induction technique documents, and additional web URLs to access the Week 2 logbooks. Participants were asked to practice the techniques and make logbook entries on consecutive days if possible, but not to practice the techniques if they were sleep deprived. They were instructed to make up for any skipped days at the end. Once sufficient sample sizes had been achieved for the three groups in Cohort 1 (permitting comparison of MILD practiced with and without two kinds of RT), the author began randomly allocating new participants to the three groups in Cohort 2 (permitting comparison of MILD with SSILD and the SSILD/MILD hybrid technique, all without RT). NALDIS group sizes were used as a guide in determining adequate group sizes in the ILDIS.

Preliminary Analyses

Analyses were conducted using IBM SPSS 26 for Windows. Non-parametric tests were used in all cases because most variables were non-normally distributed. There was no significant difference in the proportions of participants who were employed non-students, students, and unemployed or retired who did and did not complete the full study: χ 2 (2, N = 1615) = 3.43, p = 0.180, V = 0.05. The proportion of participants who reported prior experience with lucid dreaming techniques at pre-test was significantly higher for participants who completed the full study (54.9%) compared to those who did not (43.5%): χ 2 (1, N = 1615) = 14.59, p = 0.001, V = 0.10. Mann-Whitney tests indicated that participants who completed the full study had significantly higher general dream recall rates and P Lucid tech freq at pre-test. These findings and descriptive statistics for pre-test variables are presented in Table 1 .

www.frontiersin.org

Table 1. Descriptive statistics for pre-test variables with Mann-Whitney tests for differences between participants who did and did not complete the full study.

There were no significant differences between Cohort 1 and Cohort 2 on any pre-test, Week 1 or Week 2 variables except for: P Age (Cohort 1 M = 32.4, SD = 10.2; Cohort 2 M = 37.2, SD = 13.4; Z = 3.28, p = 0.001, r = 0.17); Week 1 L Sleep quality (Cohort 1 M = 3.6, SD = 0.5; Cohort 2 M = 3.4, SD = 0.5; Z = 2.10, p = 0.036, r = 0.11); and Week 1 Days to complete log (Cohort 1 M = 7.8, SD = 1.5; Cohort 2 M = 7.9, SD = 6.8; Z = 3.95, p = 0.001, r = 0.21). There were no significant differences between the three groups within Cohort 1 or within Cohort 2 on these variables. Non-significant test results are not reported for the sake of brevity. Descriptive statistics and Wilcoxon tests of differences between Week 1 and Week 2 logbook variables are presented in Table 2 . Results showed that participants reported significantly higher L Time asleep and significantly lower general dream recall rates, L Tiredness on waking and L Total log entries in Week 2 of the study compared to in Week 1.

www.frontiersin.org

Table 2. Descriptive statistics and Wilcoxon tests for differences between week 1 and week 2 logbook variables for participants who completed the full study.

Relationships With Lucid Dreaming

It was hypothesized that general dream recall rates would be positively correlated with lucid dreaming frequency at both pre-test and during Week 2. Spearman rho non-parametric correlations supported the hypothesis and are presented in Table 3 . All pre-test general dream recall variables were related to P DC Lucid per month . Correlations between pre-test general dream recall variables and Week 2 L DRF Lucid were weaker but still significant in all cases. All Week 2 general dream recall variables were significantly correlated with both P DC Lucid per month and Week 2 L DRF Lucid , with the relationships being stronger with Week 2 L DRF Lucid in all cases. This pattern of findings highlights the imperative to not treat retrospective and logbook variables of dream recall as equivalent (see Aspy et al., 2017 ; see also Aspy, 2016 ). A weak correlation was observed between P Lucid tech freq and P DC Lucid per month but not with Week 2 L DRF Lucid . Pre-test and Week 2 lucid dreaming rates were positively correlated. P Age was weakly correlated with P DC Lucid per month but not with L DRF Lucid.

www.frontiersin.org

Table 3. Spearman rho non-parametric correlations between pre-test and week 2 lucid dreaming rates and other pre-test and week 2 variables.

Lucid Dream Induction

It was hypothesized that Week 2 lucid dreaming rates would be significantly higher than Week 1 lucid dreaming rates. This hypothesis was supported. Dependent samples Wilcoxon tests showed that Week 2 L DRF Lucid was significantly higher for all participants combined and for each of the six Week 2 groups, with medium to large effect sizes in all cases. These results are presented in Table 4 . Logbook day was significantly related to L DRF Lucid in both Week 1 [χ 2 (6) = 13.21, N = 2448, p = 0.040, V = 0.07] and Week 2 [χ 2 (6) = 28.51, N = 1647, p = 0.001, V = 0.13], with the tendency for L DRF Lucid to decrease slightly over time. Because of the significant difference in L Total Log entries between Week 1 ( M = 6.9) and Week 2 ( M = 4.6) noted in section “Preliminary Analyses,” there were concerns that the Week 2 L DRF Lucid rate may be inflated compared to the Week 1 L DRF Lucid rate. To control for this issue, analyses were repeated comparing mean L DRF Lucid rates based on only the first four logbook days of Week 1 and Week 2. L DRF Lucid was again significantly higher for all participants combined and for participants in all six of the Week 2 groups, confirming the effectiveness of the techniques. Independent samples Kruskal-Wallis tests showed that there were no significant group differences within Cohort 1 (χ 2 = 1.51, p = 0.471, r = 0.06) or Cohort 2 (χ 2 = 4.16, p = 0.125, r = 0.11) in Week 2 L DRF Lucid. The combined L DRF Lucid rate for the two MILD + WBTB groups that did RT during the day ( n = 88, M = 12.1%, SD = 20.4%) was compared to the combined rate for the two MILD + WBTB groups that did not do RT during the day ( n = 118, M = 19.4%, SD = 27.8%). Results from a Mann-Whitney test were non-significant ( Z = 1.94, p = 0.052, r = 0.14).

www.frontiersin.org

Table 4. Differences between week 1 and Week 2 lucid dreaming rates for all participants combined and for each of the six week 2 groups.

Relationships With Technique Practice Variables

Relationships between L DRF Lucid and variables that operationalize the way in which the lucid dreaming techniques were practiced were assessed using Spearman rho non-parametric correlations and are presented with descriptive statistics in Table 5 . All correlations were non-significant except for a weak correlation between L Fast cycles performed by participants in Group 5: SSILD + WBTB (no RT) and L DRF Lucid . The results remained non-significant in all cases when correlations were repeated for each group individually, except for a weak negative correlation observed between L Technique min and L DRF Lucid in Group 5: SSILD + WBTB (no RT) ( r s = -0.16, p = 0.013, n = 256).

www.frontiersin.org

Table 5. Spearman rho non-parametric correlations between Week 2 lucid dreaming rates and variables that operationalize the way in which the lucid dream induction techniques were practiced.

Participants turned on the light when they awoke to practice lucid dreaming techniques on 467 occasions (28.7%) as opposed to keeping the light turned off. A 2 × 2 Chi 2 test showed that this was not related to lucid dreaming: χ 2 (1, N = 1626) = 0.30, p = 0.582, V = 0.01. Participants got out of bed after the alarm went off and before practicing lucid dreaming techniques on 1140 occasions (70.1%) as opposed to staying in bed. A 2 × 2 Chi 2 test showed that this was not related to lucid dreaming: χ 2 (1, N = 1624) = 1.08, p = 0.298, V = 0.03. Participants fell asleep while performing lucid dreaming techniques on 1162 occasions (70.7%). A 2 × 2 Chi 2 test showed that this was not related to lucid dreaming: χ 2 (1, N = 1642) = 0.01, p = 0.966, V = 0.01.

A 2 × 2 Chi 2 test was conducted to assess the hypothesis that lucid dreaming rates would be significantly higher when participants took 5 min or less to fall asleep after practicing lucid dreaming techniques compared to when they took more than 5 min to fall asleep. Mean Week 2 L DRF Lucid was 17.5% ( SD = 38.1%) for 177 occasions when participants fell asleep within 5 min or less, compared to 13.8% ( SD = 34.6%) for 275 occasions when participants took more than 5 min to return to sleep. However, this difference was not significant: χ 2 (1, n = 452) = 1.14, p = 0.286, V = 0.05. Therefore, these findings did not support the hypothesis. To further explore the hypothesis, another 2 × 2 Chi 2 test was conducted using the criterion of 10 min or less instead of 5 min or less. Mean L DRF Lucid was 18.3% ( SD = 38.7%) for 263 occasions when participants fell asleep within 10 min or less, compared to 11.1% ( SD = 31.5%) for 189 occasions when participants took more than 10 min to return to sleep. This difference was statistically significant: χ 2 (1, n = 452) = 4.33, p = 0.037, V = 0.10. When this test was repeated for each of the six groups individually the results were non-significant in all cases. This may be due to insufficient statistical power.

Additional Exploratory Analyses

Mann-Whitney tests were conducted to further explore factors related to the success rate of the lucid dream induction techniques and are presented in Table 6 . On nights when participants were successful in inducing lucid dreams, they had significantly better sleep quality and significantly higher general dream recall compared to nights when they failed to induce lucid dreams. Participants in Group 5: SSILD + WBTB (no RT) also did more fast cycles on nights when they had lucid dreams. As noted in section “Relationships With Lucid Dreaming,” there was no significant correlation between P Lucid tech freq and Week 2 L DRF Lucid . Further to this, a Mann-Whitney test showed that there was no difference in Week 2 L DRF Lucid between participants who had prior lucid dream induction experience ( M = 15.3%, SD = 24.9%) and participants without prior experience ( M = 16.4%, SD = 25.7%): Z (355) = 0.75, p = 0.454, r = 0.04.

www.frontiersin.org

Table 6. Mann–Whitney tests for differences in week 2 logbook variables between nights when practice of lucid dream induction techniques was and was not followed by lucid dreaming.

General Discussion

Participants of the International Lucid Dream Induction Study (ILDIS; N = 355) completed a pre-test questionnaire, a baseline Week 1 logbook period, and then practiced one of six different combinations of lucid dream induction techniques in Week 2. All six technique combinations were effective.

Lucid Dream Induction Techniques

Reality testing (rt).

No significant correlations were observed between number of RT performed each day and lucid dreaming incidence. This replicates the lack of significant correlations in the RT only and the RT + WBTB + MILD groups of the NALDIS, and the lack of correlation reported by Konkoly and Burke (2019) . There was no significant difference in lucid dreaming rate between the MILD + WBTB groups that did and did not perform RT during the day. These findings are consistent with the NALDIS and studies by LaBerge (1988) and Taitz (2011) , in which RT was ineffective. It remains possible that RT is effective over longer periods of time, as found for 3 weeks in studies by Purcell et al. (1986) and Purcell (1988) , and 8 weeks in a study by Schlag-Gies (1992) . Many participants complained that performing RT was burdensome and difficult to remember. This burden may reduce motivation and compliance with more effective techniques when practiced in combination. Lucid dream induction studies should avoid daytime RT unless this technique is of specific interest. The present author believes that RT is still a valuable technique for confirming whether one is dreaming, and as a specialized lucid dreaming practice for cultivating mindfulness, which is associated with lucid dreaming ( Stumbrys et al., 2015 ).

The Mnemonic Induction of Lucid Dreams (MILD) Technique

The MILD technique was effective in four separate experimental groups, two of which involved performing RT during the day. As discussed above, the addition of RT did not result in higher lucid dreaming rates. The weighted average lucid dreaming rate for the four MILD technique groups was 16.5%. This is close to the success rate reported in the NALDIS of 17.4%. These findings replicate the NALDIS and several other studies that have shown the MILD technique to be effective ( LaBerge, 1988 ; Levitan, 1989 , 1990a , 1990b , 1991 ; Edelstein and LaBerge, 1992 ; Levitan et al., 1992 ; LaBerge et al., 1994 , 2018 ; Levitan and LaBerge, 1994 ; Saunders et al., 2017 ; Konkoly and Burke, 2019 ). Although there were no statistically significant differences between the effectiveness of the hybrid SSILD/MILD technique and the other techniques in Cohort 2, results show that the overall lucid dreaming rate in Week 2, the improvement in week 2 compared to Week 1, and the effect size were all lowest for the SSILD/MILD hybrid group.

The Senses Initiated Lucid Dream (SSILD) Technique

The SSILD technique was shown to be effective, with a large effect size and a Week 2 lucid dreaming rate of 16.9%. This rate is almost identical to the weighted average rate for the four groups that practiced the MILD technique ( M = 16.5%), as well as the RT + WBTB + MILD group of the NALDIS ( M = 17.4%). These findings indicate that the SSILD technique is similarly effective for inducing lucid dreams as the MILD technique. There are several possible explanations for how the SSILD technique may induce lucid dreams. One is that repeatedly focusing attention on the visual, auditory and kinesthetic sensory modalities causes a generally increased awareness of perceptual stimuli that persists into REM sleep, making it more likely that the practitioner will notice that they are dreaming, either through generally increased awareness, or through recognition of anomalies within the dream. This could also occur if repeated sensory modality shifts persist upon entering REM sleep. Indeed, one participant reported: “as I was drifting off to sleep, I found myself continuing to do the technique, even though I wasn’t trying to.” Another possible explanation is that repeatedly refocusing one’s attention on different types of perceptual stimuli causes a general increase in cortical activation that increases the likelihood of lucid dreaming.

Predictors and Effects of Lucid Dream Induction

Prior technique experience.

There was no relationship between Week 2 lucid dreaming and whether participants had ever practiced a lucid dream induction technique, nor with the frequency of practice for those who did have prior experience. This indicates that MILD and SSILD combined with WBTB can be used successfully regardless of baseline lucid dreaming or prior technique experience.

General Dream Recall

In Week 2, lucid dreaming rates were significantly correlated with general dream recall rates. Pre-test lucid dreaming was also correlated with pre-test general dream recall. Furthermore, participants recalled significantly more dreams on nights when lucid dreaming occurred following technique practice. General dream recall was significantly lower in Week 2 compared to Week 1, indicating that the increased lucid dreaming rates cannot be attributed to simply recalling more dreams of all types. Taken together, these findings provide further support for the theory that superior general dream recall is conducive to lucid dreaming (see Aspy et al., 2017 ) and that general dream recall is a strong predictor of lucid dreaming (see Erlacher et al., 2014 ).

Technique Practice Variables

Lucid dreaming was not related to any of the variables that operationalized the way in which the lucid dream induction techniques were practiced, except for a weak correlation with the number of fast cycles in the SSILD + WBTB (no RT) group. The explanation for this correlation is unclear. Type 1 error is a likely possibility ( p = 0.039).

Time Taken to Return to Sleep

In the NALDIS, lucid dreaming occurred 86.2% more often when participants fell asleep within 5 min of completing the MILD technique. This finding was not replicated in the ILDIS. However, upon further exploration, it was found that lucid dreaming occurred 64.9% more often on nights when participants of the ILDIS fell asleep within 10 min ( L DRF Lucid M = 18.3%) compared to nights when they took more than 10 min ( L DRF Lucid M = 11.1%). This effect is weaker than in the NALDIS. A possible explanation is that participants of the ILDIS were able to fall asleep more quickly in general due to being given suggestions for how to do this. Notwithstanding, findings from the ILDIS provide further support that lucid dreaming techniques are more effective when one can return to sleep quickly. For the MILD technique, this probably makes it more likely that the mnemonic intention to remember that one is dreaming will be recalled during REM sleep. For the SSILD technique, it may be due to increased cortical activation and/or increased awareness of perceptual stimuli being more likely to persist into REM sleep.

Effects of Lucid Dream Induction on Sleep

Sleep quality was superior on nights when participants successfully induced lucid dreams compared to nights when they failed to induce lucid dreams. Participants also reported significantly more time asleep and significantly less tiredness on waking in Week 2 compared to Week 1. These findings indicate that sleep quality was not adversely affected by successful induction of lucid dreams but may have been adversely affected by unsuccessful attempts. This would be expected if the probability of success is related to the amount of time taken to return to sleep. These findings are consistent with findings from the NALDIS, whereby successful lucid dream induction using the MILD technique was related to the amount of time taken to return to sleep and did not adversely affect sleep quality. Vallat and Ruby (2019) have recently drawn attention to the fact that increasing the frequency of lucid dreams may have unknown negative impacts on the usual processes that occur during REM sleep, due to the fact that lucid dreaming involves a brain state that is neurologically distinct from non-lucid REM sleep. They also raised concerns about potential negative health impacts of the sleep disruption inherent in many lucid dreaming techniques. Soffer-Dudek (2020) raised similar concerns about the effects of lucid dreaming on sleep as well as potential disruptions to reality-fantasy boundaries, which may be of particular concern to clinical populations with disorders such as pscyhosis. More research is needed to investigate the impacts of lucid dreaming generally, and lucid dreaming training specifically, on sleep quality.

Strengths and Limitations

Strengths include the wide range of measures used, the use of measures that operationalized the way in which lucid dream induction techniques were practiced, the comparison of six different lucid dream induction technique combinations, and the large and highly diverse international sample of participants that were mostly employed non-students (71.8%), with nearly equal proportions of people who did (54.9%) and did not (45.1%) have prior lucid dreaming technique experience. Indeed, the ILDIS is the largest study of lucid dream induction techniques to date. As with the NALDIS, the ILDIS has high ecological validity. Participants practiced the techniques in their own homes using written instructions, which reflects how cognitive lucid dream induction techniques are usually practiced. A limitation of the ILDIS is the high attrition rate from the initial sample that completed the pre-test questionnaire ( N = 1618) to the final sample ( N = 355). Findings are likely to be most generalizable to people who are highly motivated to learn lucid dreaming. The use of self-report measures is a potential limitation to the findings that lucid dream induction did not adversely affect sleep quality. This is because the excitement of having a lucid dream may have counteracted feelings of tiredness upon waking. Another limitation is that the large number of statistical tests increases the familywise error rate. Results that are only marginally significant should therefore be interpreted with caution.

Directions for Future Research

Further research is needed to gain a deeper understanding of the mechanisms through which the MILD and SSILD techniques work. This may yield potential avenues for refinement. One approach could be to ask participants to describe in detail exactly how they become lucid in each lucid dream, including whether they thought about or practiced the techniques in their dreams prior to becoming lucid. Sleep laboratory research could investigate whether the SSILD technique causes increased cortical activation and whether this activation is correlated with lucid dreaming. Further research is also needed to investigate the effectiveness of practicing the MILD, SSILD and RT techniques over longer periods of time than the single week used in the present study, and the effects of lucid dreaming training on sleep quality.

Findings provide further evidence that superior general dream recall is conducive to lucid dreaming. Thus, it may be possible to increase the effectiveness of cognitive lucid dream induction techniques using drugs and supplements that enhance dream recall. In a small pilot study by Ebben et al. (2002) , ingestion of vitamin B6 (pyridoxine hydrochloride) prior to sleep was found to significantly enhance dream recall compared to placebo. In a larger replication study ( Aspy et al., 2018 ), participants recalled 64.1% more dream content when they took 240 mg of vitamin B6 directly before bed compared to placebo. Future research should compare the effectiveness of cognitive lucid dream induction techniques both with and without vitamin B6 before bed.

Currently, the most evidence-based substance for inducing lucid dreams is Galantamine, a widely used and well-tolerated acetylcholine-esterase inhibitor that influences the REM-on neurotransmitter acetylcholine ( LaBerge, 2004 ; Yuschak, 2006 ; Sparrow et al., 2016 , 2018 ; LaBerge et al., 2018 ). In the most recent study by LaBerge et al. (2018) , lucid dreaming occurred on 42% of nights when participants ingested 8 mg of Galantamine in addition to practicing the MILD technique and, in most cases, using an external LED light stimulation device. According to Yuschak (2006) , Galantamine is more effective when combined with Alpha-GPC, a form of choline that acts as a precursor to acetylcholine. It may be even more effective to take vitamin B6 before bed and then a combination of Galantamine and Alpha-GPC during a WBTB period 5 h after going to sleep, before practicing a cognitive lucid dream induction technique such as MILD or SSILD and then returning to sleep within 5–10 min. An external light stimulation device may further increase the success rate (see Mota-Rolim et al., 2019 ). This combination of cognitive, pharmacological and external stimulation techniques is currently the most promising approach to lucid dream induction.

Future studies should operationalize the way in which lucid dream induction techniques are practiced, use valid and reliable measures of dream recall, and avoid the many methodological limitations of prior lucid dream induction studies (see Stumbrys et al., 2012 ; Aspy et al., 2017 ). These methodological issues – especially the inconsistency in the way that lucid dreaming rates are operationalized – are a major impediment to research progress. The present author implores other researchers to, at minimum, report the L DRF Lucid rate based on daily logbook observations in all lucid dream induction studies, so that the effectiveness of techniques can be determined and compared (see section “Materials”).

Findings provide the strongest evidence to date that the MILD technique is effective for inducing lucid dreams. Findings indicate that the SSILD technique is similarly effective. In contrast, RT appears to be an ineffective lucid dream induction technique – at least for short periods such as 1 week in the present study.

Data Availability Statement

The datasets generated for this study are available on request to the corresponding author.

Ethics Statement

The studies involving human participants were reviewed and approved by the School of Psychology Human Research Ethics Committee at the University of Adelaide. The patients/participants provided their written informed consent to participate in this study.

Author Contributions

DA-H was the sole author of this study and was solely responsible for all tasks involved. This includes experiment design, experiment management, data collection, data analysis, literature review, and manuscript authorship.

Conflict of Interest

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Aspy, D. J. (2016). Is dream recall underestimated by retrospective measures and enhanced by keeping a logbook? An empirical investigation. Consciousness Cogn. 42, 181–203. doi: 10.1016/j.concog.2016.03.015

PubMed Abstract | CrossRef Full Text | Google Scholar

Aspy, D. J., Delfabbro, P., Proeve, M., and Mohr, P. (2017). Reality testing and the mnemonic induction of lucid dreams: findings from the national australian lucid dream induction Study. Dreaming 27, 206–231. doi: 10.1037/drm0000059

CrossRef Full Text | Google Scholar

Aspy, D. J., Madden, N. A., and Delfabbro, P. (2018). Effects of vitamin B6 (pyridoxine) and a B complex preparation on dreaming and sleep. Percept. Motor Skills 125, 451–462.

Google Scholar

Baird, B., Mota-Rolim, S. A., and Dresler, M. (2019). The cognitive neuroscience of lucid dreaming. Neurosci. Biobehav. Rev. 100, 305–323. doi: 10.1016/j.neubiorev.2019.03.008

Brown, R., and Donderi, D. C. (1986). Dream content and self-reported well-being among recurrent dreamers, past recurrent dreamers, and nonrecurrent dreamers. J. Pers. Soc. Psychol. 50, 612–623. doi: 10.1037/0022-3514.50.3.612

de Macêdo, T. C. F., Ferreira, G. H., de Almondes, K. M., Kirov, R., and Mota-Rolim, S. A. (2019). My dream, my rules: can lucid dreaming treat nightmares? Front. Psychol. 10:2618. doi: 10.3389/fpsyg.2019.02618

Downs, S. H., and Black, N. (1998). The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J. Epidemiol. Commun. Health 52, 377–384. doi: 10.1136/jech.52.6.377

Dyck, S., Schredl, M., and Kühnel, A. (2017). Lucid dream induction using three different cognitive methods. Int. J. Dream Res. 10, 151–156.

Ebben, M., Lequerica, A., and Spielman, A. (2002). Effects of pyridoxine on dreaming: a preliminary study. Percept. Motor Skills 94, 135–140. doi: 10.2466/pms.2002.94.1.135

Edelstein, J., and LaBerge, S. (1992). The best time for lucid dreaming: naps, mishaps, and recaps. NightLight 4, 4–9.

Erlacher, D., Schädlich, M., Stumbrys, T., and Schredl, M. (2014). Time for actions in lucid dreams: effects of task modality, length, and complexity. Front. Psychol. 4:1013. doi: 10.3389/fpsyg.2013.01013

Erlacher, D., and Schredl, M. (2010). Practicing a motor task in a lucid dream enhances subsequent performance: a pilot study. Sport Psychol. 24, 157–167. doi: 10.1123/tsp.24.2.157

Franc, P., Schadlich, M., and Erlacher, D. (2014). Lucid dream induction by visual and tactile stimulation: an exploratory sleep laboratory study. Int. J. Dream Res. 7, 61–66.

Hobson, A. (2009). The neurobiology of consciousness: lucid dreaming wakes up. Int. J. Dream Res. 2, 41–44.

Holzinger, B., Klösch, G., and Saletu, B. (2015). Studies with lucid dreaming as add-on therapy to Gestalt therapy. Acta Neurol. Scand. 131, 355–363. doi: 10.1111/ane.12362

Konkoly, K., and Burke, C. T. (2019). Can learning to lucid dream promote personal growth? Dreaming 29, 113–126. doi: 10.1037/drm0000101

Kumar, G., Sasidharan, A., Nair, A. K., and Kutty, B. M. (2018). Efficacy of the combination of cognitive training and acoustic stimulation in eliciting lucid dreams during undisturbed sleep: a pilot study using polysomnography, dream reports and questionnaires. Int. J. Dream Res. 11, 197–202.

LaBerge, S. (1980). Lucid Dreaming: An Exploratory Study of Consciousness During Sleep. Unpublished doctoral dissertation, Stanford University, Stanford, CA.

LaBerge, S. (1985). Lucid Dreaming: The Power of Being Awake and Aware in Your Dreams. Los Angeles, CA: Tarcher.

LaBerge, S. (1988). Induction of lucid dreams including the use of the Dreamlight. Lucidity Lett. 7, 15–21.

LaBerge, S. (2004). Substances that Enhance Recall and Lucidity During Dreaming. United States patent application publication no. US 2004/0266659 A1. Santa Clara, CA: Palo Alto Network.

LaBerge, S., and DeGracia, D. J. (2000). “Varieties of lucid dreaming experience,” in Individual Differences in Conscious Experience , eds R. G. Kunzendorf and B. Wallace (Amsterdam: John Benjamins Publishing Company), 269–307.

LaBerge, S., LaMarca, K., and Baird, B. (2018). Pre-sleep treatment with galantamine stimulates lucid dreaming: a double-blind, placebo-controlled, crossover study. PLoS One 13:e0201246. doi: 10.1371/journal.pone.0201246

LaBerge, S., Phillips, L., and Levitan, L. (1994). An hour of wakefulness before morning naps makes lucidity more likely. NightLight 6, 1–4.

LaBerge, S., and Rheingold, H. (1991). Exploring the World of Lucid Dreaming. Canada: The Ballantine Publishing Group.

Lancee, J., van den Bout, J., and Spoormaker, V. I. (2010). Expanding self-help Imagery Rehearsal Therapy for nightmares with sleep hygiene and lucid dreaming: a waiting-list controlled trial. Int. J. Dream Res. 3, 111–120.

Levitan, L. (1989). A comparison of three methods of lucid dream induction. NightLight 1, 9–12.

Levitan, L. (1990a). Is fifteen minutes enough? It’s too soon to tell. NightLight 2, 4–14.

Levitan, L. (1990b). The best time for lucid dreaming. NightLight 2, 9–11.

Levitan, L. (1991). Get up early, take a nap, be lucid. NightLight 3, 1–9.

Levitan, L., and LaBerge, S. (1994). Of the MILD technique & dream recall, of minds & dream machines. NightLight 6, 9–12.

Levitan, L., LaBerge, S., and Dole, J. (1992). Morning naps are better than afternoon naps for lucid dreaming. NightLight 4, 4–10.

Love, D. (2013). Are You Dreaming? Exploring Lucid Dreams a Comprehensive Guide. London: Enchanted Loom Publishing.

Mota-Rolim, S. A., Pavlou, A., Nascimento, G. C., Fontenele-Araujo, J., and Ribeiro, S. (2019). Portable devices to induce lucid dreams – Are they reliable? Front. Neurosci. 13:428. doi: 10.3389/fnins.2019.00428

Mota-Rolim, S. A., Targino, Z. H., Souza, B. C., Blanco, W., Araujo, J. F., and Ribeiro, S. (2013). Dream characteristics in a Brazillian sample: an online survey focusing on lucid dreaming. Front. Hum. Neurosci. 7:836. doi: 10.3389/fnhum.2013.00836

Purcell, S. (1988). The Education of Attention to Dreaming in High and Low Frequency Dream Recallers: The Effects on Dream Self-Reflectiveness Lucidity and Control. Unpublished doctoral dissertation, Carleton university, Canada.

Purcell, S., Mullington, J., Moffitt, A., Hoffmann, R., and Pigeau, R. (1986). Dream self-reflectiveness as a learned cognitive skill. Sleep 9, 423–437. doi: 10.1093/sleep/9.3.423

Reed, H. (1973). Learning to remember dreams. J. Hum. Psychol. 13, 33–48. doi: 10.1177/002216787301300305

Saunders, D. T., Clegg, H., Roe, C. A., and Smith, G. D. (2017). Exploring the role of Need for Cognition, Field Independence and Locus of Control on the incidence of lucid dreams during a 12-week induction study. Dreaming 27, 68–86. doi: 10.1037/drm0000044

Saunders, D. T., Roe, C. A., Smith, G., and Clegg, H. (2016). Lucid dreaming incidence: a quality effects meta-analysis of 50 years of research. Consciousness Cogn. 43, 197–215. doi: 10.1016/j.concog.2016.06.002

Schlag-Gies, C. (1992). Untersuchung der Effektivität zur Induktion von Klarträumen. Unpublished diploma thesis, Saarland University, Saarbrücken.

Schredl, M. (2004). Reliability and stability of a dream recall frequency scale. Percept. Mot. Skills 98, 1422–1426. doi: 10.2466/pms.98.3c.1422-1426

Sleep Paralysis Information Service (2013). What is it?. Available at: http://www.spis.org.uk/ (accessed August 20, 2013).

Soffer-Dudek, N. (2020). Are lucid dreams good for us? are we asking the right question? A call for caution in lucid dream research. Front. Neurosci. 13:1423. doi: 10.3389/fnins.2019.01423

Sparrow, G., Hurd, R., Carlson, R., and Molina, A. (2018). Exploring the effects of galantamine paired with meditation and dream reliving on recalled dreams: toward an integrated protocol for lucid dream induction and nightmare resolution. Consciousness Cogn. 63, 74–88. doi: 10.1016/j.concog.2018.05.012

Sparrow, G. S., Hurd, R., and Carlson, R. (2016). Assessing the perceived differences in post-Galantamine lucid dreams vs. non-Galantamine lucid dreams. Int. J. Dream Res. 9, 71–74.

Spoormaker, V. I., and Van Den Bout, J. (2006). Lucid dreaming treatment for nightmares: a pilot study. Psychother. Psychos. 75, 389–394. doi: 10.1159/000095446

Stumbrys, T., and Daniels, M. (2010). An exploratory study of creative problem solving in lucid dreams: preliminary findings and methodological considerations. Int. J. Dream Res. 3, 121–129.

Stumbrys, T., Erlacher, D., and Malinowski, P. (2015). Meta-awareness during day and night: the relationship between mindfulness and lucid dreaming. Imag. Cogn. Pers. 34, 415–433. doi: 10.1177/0276236615572594

Stumbrys, T., Erlacher, D., Schädlich, M., and Schredl, M. (2012). Induction of lucid dreams: a systematic review of evidence. Consciousness Cogn. 21, 1456–1475. doi: 10.1016/j.concog.2012.07.003

Stumbrys, T., Erlacher, D., and Schredl, M. (2013). Testing the involvement of the prefrontal cortex in lucid dreaming: a tDCS study. Consciousness Cogn. 22, 1214–1222. doi: 10.1016/j.concog.2013.08.005

Stumbrys, T., Erlacher, D., and Schredl, M. (2016). Effectiveness of motor practice in lucid dreams: a comparison with physical and mental practice. J. Sports Sci. 34, 27–34. doi: 10.1080/02640414.2015.1030342

Taitz, I. (2011). Learning lucid dreaming and its effect on depression in undergraduates. Int. J. Dream Res. 4, 117–126.

Tholey, P. (1983). Techniques for inducing and manipulating lucid dreams. Percept. Motor Skills 57, 79–90. doi: 10.2466/pms.1983.57.1.79

University of Waterloo (2013). Preventing and Coping with Sleep Paralysis. Available at: http://watarts.uwaterloo.ca/~acheyne/prevent.html (accessed August 20, 2013).

Vallat, R., and Ruby, P. M. (2019). Is it a good idea to cultivate lucid dreaming? Front. Psychol. 10:2585. doi: 10.3389/fpsyg.2019.02585

Yuschak, T. (2006). Advanced Lucid Dreaming: The Power of Supplements. Morrisville: Lulu Enterprises.

Zhang, G. X.-L. (2013). Senses Initiated Lucid Dream (SSILD) Official Tutorial. Available at: http://cosmiciron.blogspot.com.au/2013/01/senses-initiated-lucid-dream-ssild_16.html (accessed July15, 2016).

Keywords : lucid dreaming, lucid dream induction techniques, dream recall, reality test, sleep quality

Citation: Adventure-Heart DJ (2020) Findings From the International Lucid Dream Induction Study. Front. Psychol. 11:1746. doi: 10.3389/fpsyg.2020.01746

Received: 19 December 2019; Accepted: 24 June 2020; Published: 17 July 2020.

Reviewed by:

Copyright © 2020 Adventure-Heart. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Denholm Jay Adventure-Heart, [email protected]

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • View all journals
  • My Account Login
  • Explore content
  • About the journal
  • Publish with us
  • Sign up for alerts
  • Open access
  • Published: 21 September 2022

The role of mindful acceptance and lucid dreaming in nightmare frequency and distress

  • Sofia Tzioridou   ORCID: orcid.org/0000-0002-3726-9746 1 , 2 ,
  • Martin Dresler 2   na1 ,
  • Kristian Sandberg 3   na1 &
  • Erik M. Mueller 1   na1  

Scientific Reports volume  12 , Article number:  15737 ( 2022 ) Cite this article

4855 Accesses

1 Citations

46 Altmetric

Metrics details

  • Human behaviour

A theoretical and empirical association between lucid dreaming and mindfulness, as well as lucid dreaming and nightmares has previously been observed; however, the relationship between nightmares and mindfulness has received surprisingly little attention. Here, we present the findings of two studies exploring the relation of nightmare frequency and distress with two components of mindfulness, termed presence and acceptance, as well as lucid dreaming. Study 1 (N = 338) consisted of a low percentage of frequent lucid dreamers whereas Study 2 (N = 187) consisted primarily of frequent lucid dreamers that used lucid dream induction training techniques and meditation. Across studies, nightmare-related variables showed a more robust association with mindful acceptance as opposed to mindful presence. Moreover, individuals with high levels of meditation expertise and practice of lucid dreaming induction techniques reported lower nightmare frequency. Finally, in Study 2, which consisted of frequent lucid dreamers, a positive correlation between lucid dreaming frequency and mindfulness was apparent. The present findings support the notion that wakeful mindfulness is associated with the quality of dreams and extend previous research by suggesting a disentangled role of the two facets of mindfulness in dream variation. This association remains open for experimental manipulation, the result of which could have clinical implications.

Introduction

Nightmares, defined as very disturbing dreams that awaken the sleeper (according to the International Classification of Sleep Disorders [ICSD-3] of the American Academy of Sleep Medicine (AASM) 1 , are closely associated with stress and ill-being 2 , 3 . On the other side, dispositional mindfulness, a concept inspired by Buddhist traditions, has been found to reduce stress 4 , 5 , improve sleep 6 and promote mental well-being 7 , 8 . Dispositional mindfulness has been psychometrically operationalized as unidimensional or consisting of several components, which might divergently relate with well-being and ill-being related variables 9 . Lucid dreaming—i.e. the phenomenon of becoming aware of the current dream state during ongoing sleep—has been associated with alleviated nightmare distress on the one hand 10 , and increased trait mindfulness on the other 11 . Even though an indirect link between mindfulness and nightmare frequency and distress can be assumed and some findings support it 12 , more direct relationships have received little attention. Mindfulness can be trained through meditation practices and mindfulness based interventions 7 , 13 , which can easily be integrated into already existing clinical applications targeting nightmare disorders.

In the present paper, we aim to accentuate the role of mindfulness on dream variation by briefly reviewing the clinical aspect of nightmares and therapy approaches, such as lucid dreaming therapy, as well as the theoretical and empirical association of dispositional mindfulness and dreams. We then proceed to present our findings considering the relations among nightmares, two components of mindfulness, namely mindful presence and acceptance, and lucid dreams.

Nightmare disorder and clinical interventions

Healthy individuals occasionally experience nightmares of various content and emotional intensity 14 , 15 . However, nightmare disorder is quite common, with a prevalence of around 4% in the adult population of the United States 1 . Nightmare disorder is defined based on nightmare frequency, as well as on the distress caused by the dream 1 , which is related to the affective adjustment during wake 16 .

Subsequently, nightmare disorder can result in sleep avoidance and deprivation, mood disturbance, cognitive and social function impairments, thus it can significantly reduce quality of life 17 , 18 . Recurrent nightmares are prominent in post-traumatic stress disorder (PTSD) 17 , 18 , anxiety 19 , 20 , 21 and depression 22 , 23 , 24 and have been associated with increased risk of suicide 20 , 25 even after controlling for other risk factors 26 , 27 . If treated, there is a substantial improvement in sleep quality and insomnia symptoms, daytime fatigue and sleepiness are reduced 28 , 29 , 30 .

Taking the above into account, a variety of treatment approaches, both pharmacological and behavioral, have been suggested. Some of the behavioral and psychological treatment options include lucid dreaming therapy, image rehearsal therapy (IRT), cognitive behavioral therapy for insomnia (CBT-I), exposure, relaxation and rescripting therapy (ERRT), hypnosis, progressive deep muscle relaxation, sleep dynamic therapy, systematic desensitization etc. 18 , 31 .

Lucid dreaming therapy has been suggested to be beneficial as a treatment approach, mostly in combination with other behavioral treatments 18 . If trained, lucid dreaming could reduce nightmares by resignifying the dream scene, meaning reducing the negative emotions, such as fear and threat, which arise during a nightmare, by realizing it is just a dream or even by changing the oneiric storyline 32 . It is a trainable technique that could emancipate patients from their nightmares. Some studies suggest that this empowerment about one’s dreams can reduce nightmare frequency even without reaching lucidity 33 . However, conclusions about the efficacy of lucid dreaming treatment mainly rely on case reports or in some cases non-significant positive outcomes 32 of quite underpowered empirical studies.

Nightmares and lucid dreaming

Apart from clinical studies, surveys investigating the relationship of nightmares and lucid dreaming have been conducted. In a cross-sectional study, about 64% of a sample highly interested in lucid dreaming seem to have chosen lucid dreams in order to change nightmares or bad dreams into a more pleasant experience 34 . Moreover, narcolepsy patients, who tend to experience more lucid dreams than controls, report a positive impact of dream lucidity on distress arising from nightmares 10 . It is important to note here that in spite of the fact that nightmare frequency and nightmare distress are related, a differentiation of the two is pivotal, as a variety of factors that do not relate to nightmare frequency, can contribute to and be influenced by nightmare distress 16 , 35 , 36 , 37 . It is also suggested that frequent lucid dreamers tend to encounter less threatening figures in their dreams since they can change the plot of the dream 38 , 39 . However, a number of cross-sectional studies have found a positive correlation of nightmare frequency and lucid dreaming frequency 40 , 41 , 42 or dream awareness 43 , which stands even after controlling for dream recall 40 , 41 . Since participants who report higher dream recall, also report nightmares and lucid dreams more often, it is a necessity to control for the dream recall variable 41 . The aforementioned finding of multiple studies seems to support reports of lucid dreamers that nightmares, especially recurrent nightmares, can trigger lucidity 44 , 45 .

Mindfulness

Lucid dreaming might be suggested as an antidote against nightmares, but its clinical use still remains quite narrow and the findings supporting it are scarce 32 . The beneficial role of mindfulness on psychological and physical health is on the other hand much more robust in the literature 46 , 47 . Mindfulness, an individual disposition that can be enhanced through mindfulness meditation practice 7 , can be described as the ability to be aware of the present moment and experience it with an open and non-judging attitude 48 , 49 . It has been found to increase subjective well-being and reduce common forms of psychological distress 46 and mindfulness-based therapy has been found to successfully reduce anxiety and mood problems in clinical populations 50 . Its application received increased interest in Western medical and mental health contexts some decades ago 46 and in an attempt to better define dispositional mindfulness conceptually and operationally, multiple suggestions describing a uni- 7 , dual- 51 or multi- 52 , 53 dimensional construct have been made with most researchers following the two-component model of mindfulness proposed by Bishop et al. 46 , 54 . The first component, named Self-Regulation of Attention, is the ability of bringing awareness to the current experience by regulating the focus of attention. The second component, Orientation to Experience, involves adopting an orientation characterized by curiosity, openness and acceptance toward one’s experiences in the present moment 54 . This distinction of the two components seems to be important, as studies have found that the two components do not exert the same impact on well-being and ill-being 55 . The 14-item Freiburg Mindfulness Inventory (FMI) 56 , which is used in the present study, was created as a measure of a unidimensional concept of mindfulness, but it was later suggested it can be divided into two factors of mindfulness, Presence and Acceptance 9 . These two factors are in line with the model and descriptions proposed by Bishop et al. 54 . Presence, conceptually similar to Regulation of Attention described above, refers to the ability to be fully aware of internal and external experiences of the present moment, while Acceptance, conceptually corresponding to the aforementioned component named Orientation to Experience, refers to a non-judging, curious and open mindset towards these experiences 9 , 11 , 54 . Studies using this particular inventory found that Acceptance is the component that seems to influence depression and anxiety, whereas Presence exerts an impact indirectly by supporting the development of an accepting attitude 9 . Keeping the aforementioned definitions in mind, below we will present the theoretical and empirical association of mindfulness with dreams.

Mindfulness and lucid dreaming

A great variation in consciousness is experienced constantly during the sleep–wake cycle in humans. Non-lucid dreaming is considered to consist only of primary consciousness, meaning perception and emotions, while lacking higher order (secondary) consciousness, like self-reflective awareness, volition and meta-cognition, which is present during wakefulness 57 , 58 . Therefore, in non-lucid dreaming, people do not realize they are dreaming. However, there are experiences in wakefulness, such as mind wandering and automatic behaviors, when higher secondary consciousness seems to be absent 59 . In addition, the rare state of lucid dreaming indicates, by definition, the presence of reflective capabilities with higher order aspects of consciousness, such as metacognition 60 , 61 , 62 and volition 63 . Neuroscientific findings support this by revealing shared neural mechanisms, located in the prefrontal brain regions (BA9/10), between lucid dreaming and metacognition 62 .

Mindfulness is also related to metacognition 64 , 65 , 66 and seems to influence waking states in which secondary consciousness is considered absent 67 , 68 , 69 , 70 . Notably, the neural correlates of dispositional mindfulness have been located in the same brain regions (medial prefrontal cortex) as metacognition and lucid dreaming 39 , 71 . Based on the aforementioned theoretical association, it could be hypothesized that mindfulness training could also exert an influence on dreaming via altering meta-cognition, therefore increasing the likelihood of experiencing lucid dreams.

Indeed, apart from the conjectural relation described above, lucid dreaming seems to have an empirical association with aspects of trait mindfulness 11 , 72 . Meditation practice has been suggested to promote lucidity in dreams 72 , 73 , 74 , 75 . In fact, studies report mindfulness in wakefulness to be positively related to lucidity in dreams, but only in participants who are practicing meditation 11 , 72 . In addition, while meditation expertise seems to be related to lucid dream frequency in some 72 but not other 11 studies, an 8-week mindfulness based stress reduction course did not change lucid dreaming frequency 72 .

In regard to the components of mindfulness, Presence, as measured with the FMI, was found to be associated with lucidity in dreams more robustly than Acceptance 11 . As discussed in Stumbrys et al. 11 , mindful acceptance differs from lucidity; Acceptance refers to a non-judging and accepting attitude toward emotions and experiences with no intention to change or control them 54 , 76 , while in dream lucidity, the dreamer is usually actively changing the dream environment and takes action to control the dream narrative according to their will 11 , 77 . In line with mindful presence, which by definition represents the increased ability to be aware of internal experiences, in dream lucidity the dreamer has to be aware of the mental event they experience, meaning that they are aware that they are dreaming. In another study, facets comparable to Presence here, were also found to be related to lucidity in dreams, whereas facets closer to Acceptance did not show this relation 72 .

Mindfulness and nightmares

Despite the fact that, as seen above, an association between lucid dreaming and mindfulness, as well as lucid dreaming and nightmares 41 , 42 has been observed, the relationship between nightmares and mindfulness has received surprisingly little attention, especially when considering that mindfulness interventions seem to reduce stress 4 , 5 , 78 , 79 , improve sleep 6 , 80 , 81 , 82 and ameliorate sleep disturbances, that arise from stress 83 .

According to the continuity hypothesis, waking states and concerns are reflected in dream imagery 84 , 85 and neuroscientific findings suggest that waking emotional patterns are preserved in dreams, influencing the dream contents. In this regard, studies have found that if someone is experiencing symptoms of anxiety or depression during waking life, this could also be evident in their dream imagery 86 , 87 . Moreover, it has been suggested that after only one week of meditation, anxiety and depression scores decrease and dream imagery changes 87 . Anxiety has also been linked to negative dream affect, whereas peace of mind, described as the inner peace and harmony, is related to positive dream affect 88 .

To our knowledge, two studies have investigated the relation of mindfulness and disturbed dreaming. In one study, mindfulness was found to be inversely related to disturbed dreaming and dream anxiety and to predict less severe dream disturbances after controlling for trait anxiety 12 . In the other study, mindfulness was negatively correlated with nightmare frequency 89 . However, both these studies assessed and analyzed mindfulness as a unidimensional construct. We argue here that as seen above with Presence and lucid dreaming 11 , the components of mindfulness might play different roles in relation to nightmares. Based on literature suggesting that mindful acceptance has the leading role when it comes to psychological well-being 55 , as well as influencing depression and anxiety 9 , we could assume three possible pathways of how mindful acceptance might also have a leading role in relation to nightmares. With the continuity hypothesis in mind, the first could be that mindful acceptance is helpful with anxiety and depression in waking and this is also apparent in the dream imagery. The second interpretation would be that by adopting an attitude of curiosity, openness and acceptance, one would allow oneself to experience the dream stressors as they come without the need to avoid or suppress them, eventually making them less distressing. Indeed, mindfulness has been widely viewed as an important skill facilitating emotional regulation and promoting positive emotional states 7 , 90 , 91 . Thirdly, via the same mechanism, one might experience nightmares, but instead of resorting to preoccupation or suppression of the experience when they wake up, they embrace the experience, making it less distressing and memorable. The latter is supported by evidence that mindfulness promotes quicker recovery from unpleasant emotional states 92 . To put it concisely, either the dreams are different because the waking state has changed or the dream imagery stays the same, but is interpreted or perceived as less distressing during dreaming or after waking up.

Overall, the relation of nightmares to mental ill-being has been well established 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , but research on preventive factors, such as mindfulness, seems to have been widely neglected. Even though a study using the FMI has already found a negative correlation between the total FMI score and nightmare frequency 89 , the relation of the particular facets of mindfulness has not been previously discussed. As mentioned above, the two components do not seem to affect well-being and ill-being the same way 55 , leading us to the assumption that a similar observation might be apparent for dream variation as well, namely nightmares and lucid dreaming.

As discussed above, lucid dreaming has been found to be associated with both nightmares 10 , 40 , 41 , 42 , 43 and mindfulness 11 , 72 , as well as with the mindfulness component presence 11 . However, studies on the topic have presented data of samples with more frequent lucid dreamers than the general population. Here, we present the findings of two questionnaire-based studies with samples that plainly differ on the engagement with lucid dreaming.

In order to extend previous findings and elucidate the association of mindfulness and dreaming, in the present paper, we examine the relationship among dream variation, more specifically nightmares and lucid dreams, and the two aspects of mindfulness, Presence and Acceptance, as measured with the 14-item FMI 56 . In one of the studies, we also investigate both nightmare frequency and distress, an important distinction when measuring nightmares as mentioned above 16 , 35 , 36 , 37 .

Data were gathered in the context of two separate large-scale studies. Data from Study 1 were gathered in the context of EU COST Action CA18106 The Neural Architecture of Consciousness as part of a larger dataset from Aarhus University, Denmark. The study was approved by the local ethics committee, De Videnskabsetiske Komitéer for Region Midtjylland and all methods were performed in accordance with the relevant guidelines and regulations.

Data from Study 2 were collected via an online survey conducted by the Psychology department of Marburg University with the intention of investigating meditation techniques and lucid dreaming.

Participants

For Study 1, 338 healthy participants (201 females) gave informed consent to participate in the survey. The mean age was 25.29 (SD = 4.94). For comparison to Study 2, the median age was 24.33 years (18–49).

For Study 2, 187 (120 females, 60 males, 7 other/NA) healthy participants gave their consent and completed an online survey. The age was measured as a categorical variable, median is 25–34 years old with 25.1%, 43.9% were older than 35 and 31% younger than 24. Participants in Study 2 were screened as to how often they recalled their dreams with the minimum acceptance criterion being three times a week.

The survey (Study 2) was advertised on international sites related to lucid dreaming as well as local survey websites and the university of Marburg recruitment platform. This resulted in a non-representative sample; participants were experienced with lucid dreaming training and have reported more lucid dreams than the usual population mean as discussed below. This allowed us to perform the analysis on two populations with different lucid dreaming frequency characteristics, experienced lucid dreamers (Study 2) and naive participants (Study 1).

Materials and procedure

For Study 1, all participants completed the Freiburg Mindfulness Inventory (FMI) with 14 items and a 4-point rating scale 56 , a 7-point rating item developed by Schredl 93 assessing their dream recall frequency and two 8-point rating scales developed by Stumbrys et al. 94 measuring nightmare and lucid dream frequency 94 , all in English. All the dream related questions are also included in the Mannheim Dream Questionnaire (MADRE) 95 . The nightmare and lucid dreaming questions were accompanied with the definition of the concepts mentioned in the original questionnaires 94 , 95 in order to ensure that the participants understood the concepts before replying to the question. They were presented along with 20 other psychological questionnaires in an online questionnaire session with a total duration of around 70 min. The questionnaires covered a broad range of psychological characteristics including self-reported memory, social network size, perceived stress, impulsiveness, musical sophistication and cognitive failures. Participants were instructed to complete the questionnaire session from home and to ensure that it was completed in a quiet, undisturbed setting.

For Study 2, in addition to screening and demographic data, the survey included the two scales on nightmare and lucid dream frequency mentioned above 94 , as well as the definition of the concepts 95 . It also included the FMI-14 56 , several questions assessing meditation experience, expertise, duration, type and further questions assessing sleep, chronotypes and personality. An item from the MADRE assessing nightmare distress with a five-point scale 95 was also included in the questionnaire, but participants were given the opportunity to skip the question as “not applicable” resulting to an n = 134 for this particular item. The whole survey lasted about 10 min in total. The online questionnaire was generated using SoSci Survey 96 and was made available to users via www.soscisurvey.de . The survey was conducted in English and was anonymous; however, participants were given the opportunity to enter a lottery in order to win one of three 20-dollar gift certificates, for which an e-mail address was required.

Both studies ensured that all questions were answered by not allowing participants to continue if there were missing responses, except for the nightmare distress question of Study 2 as mentioned above.

Data preparation and statistical analysis

For both studies, a Total Mindfulness score was calculated from all 14 items along with a score for Acceptance (8 items) and Presence (6 items) following the division of Kohls et al. 9 . Dream data were recoded to units of mornings per week for the dream recall scale and units of frequency per month for the nightmare and lucid dream frequency items as indicated by Stumbrys et al. 94 . Meditation expertise was calculated by summing the ratings of three items, meditation session frequency (how often they meditate), meditation experience (for how long they have been meditating for) and meditation session duration.

Next, the data were examined in terms of suitability for linear analyses. As several variables did not fulfil the requirements for parametric testing (ordinal data, normal distribution etc.), correlations were assessed with the Spearman Rho test. In addition, ordinal logistic regression analysis was performed as well as the Mann–Whitney U test.

The Jamovi open statistical platform (Version 1.6.23) was used for statistical analyses 97 .

The descriptive statistics for the samples of both studies are summarized in Table 1 in order to facilitate comparison.

In Study 1, less than one-third of the participants reported having one or more lucid dreams per month, which classifies them as frequent lucid dreamers 98 . The FMI score mean was 36.46 (SD = 5.98). For comparison, the mean score of FMI for the normal sample in the study of Walach et al. 56 was 37.24 (SD = 5.63).

In Study 2, where participants were positively selected with regard to lucid-dreaming, more than two-thirds of the participants reported having more than one lucid dream per month and more than half had already tried one or more lucid dreaming techniques, which allowed them to experience lucid dreams more frequently than the general public (24.7% as reported in Hess, Schredl and Goritz 40 ). Participants of Study 2 were also engaging in different types of meditation with 77.5% reporting that they have practiced meditation at some point during their lives. The average FMI score was 39 (SD = 7.37). For comparison, the mean score of FMI for a sample with high lucid dreaming interest, was also 39 (SD = 6.3).

Nightmare frequency

Spearman correlations show that nightmare frequency was negatively correlated with the total mindfulness score as measured with the FMI, rs (338) = − 0.193, p  < 0.001. The correlation of the two mindfulness facets separately; Presence: rs (338) = − 0.094, p  = 0.084, Acceptance rs (338) = − 0.222, p  < 0.001. Lucid dreaming frequency showed a positive correlation with nightmare frequency rs (338) = 0.238, p  < 0.001. Age showed no association with the aforementioned variables.

As suggested in the literature, controlling for dream recall is a necessity as the variable is associated with both nightmare and lucid dream frequency and can influence their relationship 41 . Taking that into account, partial correlations with dream recall as a control variable were calculated (see Table 2 ).

In order to evaluate the influence of the two components of mindfulness as assessed by the FMI on nightmare frequency, we conducted an ordinal logistic regression with the two FMI subscales, Presence and Acceptance, as predictors while controlling for age, gender and dream recall.

There was a main effect of FMI Acceptance on nightmare frequency as can been seen in Table 3 , but no effect of FMI Presence.

Subsequently, we included the variable lucid dream frequency in the model in order to control its effect. There was no effect of lucid dreaming frequency on nightmare frequency. The coefficients of FMI Acceptance remained unchanged.

The same analyses was performed for Study 2. The Spearman correlations before controlling for dream recall showed a non-significant negative correlation for nightmare frequency and FMI total rs (187) = − 0.112, p  = 0.126, as well as the two mindfulness components, FMI Presence rs (187) = − 0.056, p  = 0.449 and FMI Acceptance rs (187) = − 0.140, p  = 0.055. FMI Acceptance was negatively correlated with nightmare frequency when controlling for dream recall (see Table 4 ). No association was observed between nightmare frequency and lucid dream frequency.

In agreement with Study 1, when performing an ordinal regression, there was only a main effect of FMI Acceptance on nightmare frequency when controlling for age, gender and dream recall. The results are summarized in Table 3 .

The effect of lucid dream frequency was non-significant and the effect of FMI Acceptance remained after the addition of lucid dream frequency in the model, β  = − 0.084, SE  = 0.039, χ 2 (1, N = 187) = 4.77, OR  = 0.91, p  = 0.029.

Nightmare distress

Nightmare distress was negatively correlated with mindfulness and its components, but only the association with FMI Acceptance was significant, rs (134) = − 0.182, p  = 0.035. FMI Presence rs (134) = − 0.099, p  = 0.257 and FMI total rs (134) = − 0.169, p  < 0.051. Furthermore, a bivariate, rs (134) = − 0.193, p  = 0.026 and a partial correlation (see Table 4 ) showed a negative association between nightmare distress and lucid dream frequency.

When testing the effects of the mindfulness components with age and gender as covariates, only FMI Acceptance significantly predicted nightmare distress, After controlling for lucid dream frequency, FMI Acceptance did not predict nightmare distress, β  = − 0.081, SE  = 0.045, χ 2 (1, N = 134) = 3.25, OR  = 0.92, p  = 0.071 and the effect of lucid dream frequency on nightmare distress was not significant (see Table 5 ).

Lucid dreaming

Lucid dream frequency did not correlate with mindfulness and its components in Study 1 with both bivariate and partial correlations producing very weak, non-significant correlations (see Table 2 for partial correlation). An ordinal regression on lucid dream frequency with the two FMI components as predictors while controlling for dream recall, age and gender was conducted. There was no significant effect of the variables on lucid dream frequency. However, exploratory correlations revealed a negative correlation between nightmare frequency and an item assessing engagement in lucid dreaming techniques after controlling for dream recall, rs (338) = − 0.143, p  = 0.009 (bivariate correlation: rs (338) = − 0.103, p  = 0.057).

Lucid dreaming was positively correlated with the FMI total score, rs (187) = 0.265, p  < 0.001, FMI Presence, rs (187) = 0.238, p  = 0.001 and FMI Acceptance, rs (187) = 0.246, p  < 0.001 (see Table 4 for partial correlation).

None of the two components of mindfulness significantly predicted lucid dreaming when conducting an ordinal regression as mentioned above.

Similar to Study 1, however, the more lucid dream induction techniques participants reported to have used, the less frequent rs (187) = − 0.267, p  < 0.001 and distressing rs (134) = − 0.256, p  = 0.003 they reported their nightmares to be. The coefficients did not change substantially when controlled for dream recall.

In study 2, where meditation experience was also examined, a Mann–Whitney test indicated that the participants who have practiced meditation reported significantly lower nightmare frequency ( Mdn  = 0.25) than the participants who reported that they have never practiced meditation, Mdn  = 1, U (N mediation  = 145, N no-meditation  = 42) = 2050, p  = 0.001, r rb  = 0.33. There was no difference between the two meditation groups (Yes/No) when it came to nightmare distress.

Meditation expertise was negatively correlated with nightmare frequency, rs (187) = − 0.322, p  < 0.001, but not nightmare distress, rs (134) = − 0.052, p  = 0.55. The coefficients did not change substantially when controlled for dream recall.

In order to assess whether the relaxation effect of meditation alone influences the relationship of mindfulness and nightmares, an ordinal logistic regression with an interaction term was calculated with the aim to measure whether meditation expertise moderates the effect of FMI Acceptance on nightmare frequency, as well as nightmare distress while controlling for age, gender and dream recall. There was no effect of the FMI Acceptance on nightmare frequency β  = − 0.032, SE  = 0.028, χ 2 (1, N = 187) = 1.24, OR  = 0.96, p  = 0.266 when meditation expertise was included in the model, but no moderation occurred. The effect of meditation expertise on nightmare frequency was significant, β  = − 0.084, SE  = 0.030, χ 2 (1, N = 187) = 7.66, OR  = 0.92, p  = 0.006. On the other hand, only FMI Acceptance significantly predicted nightmare distress β  = − 0.076, SE  = 0.034, χ 2 (1, N = 134) = 4.86, OR  = 0.93, p  = 0.027 with no effect of meditation expertise β  = 4.14e−4, SE  = 0.034, χ 2 (1, N = 134) = 1.44e−4, OR  = 1, p  = 0.990.

A partial Spearman correlation (control: dream recall) revealed a positive correlation between nightmare frequency and the last time meditation was performed ( rs (145) = 0.175, p  = 0.036), meaning the longer it has been since the last meditation session, the higher the nightmare frequency. Moreover, A Kruskal–Wallis test showed that the meditation category (focused attention, open monitoring or combined) did not significantly affect nightmare frequency, H (2, N = 140) = 2.12 , p  = 0.346. Finally, the number of lucid dreaming techniques used was positively correlated with meditation expertise, ( rs (187) = 0.405, p  < 0.001).

Mindfulness is negatively associated with nightmare frequency and our results indicate mindful acceptance as the main component related to nightmare frequency, even after we controlled for lucid dreaming frequency. Acceptance, as measured by the FMI, also seems to be associated with nightmare distress. A positive correlation between mindfulness and lucid dream frequency was prominent in Study 2, as found in other studies, but we did not find an association of a particular mindfulness component with lucid dream frequency. The use of lucid dream induction techniques seems to be associated with nightmare frequency and distress, a relation that will be discussed in more detail below.

Meditation practice plays a role, as results showed that participants who reported having practiced meditation at some point in their lives, also reported lower nightmare frequency. However, meditation expertise did not seem to moderate the relationship of nightmare frequency and Acceptance. The specific type of meditation practiced was not found to play a role in relation to nightmare frequency, however, the time passed since the last meditation session is positively related to nightmare frequency. Overall, the present findings support the idea that wakeful mindfulness is associated with the quality of dreams and more specifically that facets of mindfulness might have separate roles in dream variation.

Based on the results of the two studies, nightmare frequency was negatively correlated with mindfulness, more robustly with the facet of Acceptance as measured with the FMI, extending the previous findings on a unidimensional measure of mindfulness and dream disturbances 12 , 89 . In fact, Acceptance explained nightmare frequency in both studies and explained nightmare distress measured in Study 2. It should be noted, that partial correlations between nightmare distress and the mindfulness components depicted in Table 4 should be cautiously interpreted, if at all, as controlling for dream recall here was kept as a matter of consistency rather than necessity. Overall, FMI Acceptance seems to be associated with nightmare frequency and distress in a more robust manner than FMI Presence, which is in congruence with literature suggesting that mindful acceptance is the main feature of mindfulness that both reduces distress and promotes psychological well-being 51 , 55 . Additionally, previous findings showed that attention monitoring, similar to mindful presence here, hardly predicted ill-being while most benefits on psychological well-being and ill-being depend on mindful acceptance alone 55 .

In more detail, mindful acceptance alone has been associated with lower stress, depression and anxiety 99 and lower post-traumatic stress symptoms 100 , 101 , all of which have been associated with higher nightmare experiences 24 , 102 , 103 . It has been suggested that stress is mediating the positive relationship between mindfulness and sleep quality and well-being 83 , which makes it highly possible that a similar mediation is taking place in the relationship we observed here, between mindfulness and nightmares. It is therefore of high importance that future studies investigate this possibility.

To our knowledge, a relationship between mindful acceptance and nightmares has not been previously described in the literature. This lack of evidence on how mindfulness could potentially benefit the treatment of nightmares might explain why mindfulness training has not yet received a more prominent position as a complementary method of the treatment approaches of nightmare disorder. Our findings support the theoretical assumptions of how mindful acceptance could influence nightmares, which were presented earlier. Future studies could particularly investigate the likelihood of each of these interpretations.

Lucid dreaming frequency was correlated with mindfulness and its components in Study 2 where the sample was constituted of a high percentage of frequent lucid dreamers (71.1%), higher than the sample from Stumbrys et al. (49.8%) 11 , where participants with high interest and/or engagement in lucid dreaming were recruited, and notably higher when compared to the sample of Study 1 (29.9%) that did not aim for a sample with interest in lucid dreaming. For comparison, other studies with “naïve” samples, reported lucid dreaming frequencies similar to Study 1 (24.7% 40 and 36.9% 41 ). However, the finding of Stumbrys et al. 11 , where FMI Presence predicted lucid dream frequency in a regression model could not be replicated in our studies. One possible explanation could be the difference between the sample characteristics in respect to meditation experience and expertise. In Study 2 here, 77.5% reported having some meditation experience with a median of 2–4 years as measured by a categorical variable, whereas in Stumbrys et al. 11 only 22.3% of the sample reported meditation experience with a median of 3 years. It is also worth noting that the two studies also differed in respect to nationality and language characteristics of the sample as the study of Stumbrys et al. 11 included only German-speaking participants.

Moreover, lucid dreaming frequency was negatively correlated with nightmare distress, which is in line with previous literature 10 , as discussed before. However, lucid dreaming frequency showed a positive correlation with nightmare frequency, which has been previously reported 40 , 41 , as nightmares, especially recurrent ones, can trigger lucidity 44 . It is worth noticing that the relation was only apparent in Study 1, in which only 10.9% of the frequent lucid dreamers had actively engaged with lucid dreaming training techniques in comparison to 67.7% of Study 2. Interestingly, other studies that show a positive correlation between lucid dream and nightmare frequency have also recruited convenience samples unrelated to lucid dreaming 40 , 41 , similar to Study 1. Participants with spontaneous lucid dreams might lack the empowering effect introduced by lucid dreaming training techniques that predominantly enlighten on the efficacy of controlling ones dreams. Moreover, the more lucid dreaming induction techniques our participants reported to have used, the less frequent and distressing they reported their nightmares to be. These findings support the idea, we discussed before; the empowerment someone can gain by the knowledge of potentially controlling their dreams can reduce nightmare frequency and intensity, even without reaching lucidity 32 , 33 . However, since the number of reported lucid dreaming training techniques is positively correlated with meditation expertise, we cannot exclude a possible additive effect of the two practices on nightmare related variables.

Meditation expertise was associated with nightmare frequency; however we found no link between meditation and nightmare distress. Meditation expertise did not moderate the relationship between mindfulness and the aforementioned variables, but the main effect of FMI Acceptance on nightmare frequency was decreased after meditation was added to the model, whereas it was increased for the nightmare distress variable. This could suggest that the relaxation effects of the meditation practice have a direct effect on nightmare frequency, possibly due to its stress-relieving properties, whereas the effect on nightmare distress might primarily be achieved through meditation practices that promote mindfulness (mindfulness based meditation). This is also supported by the positive relation of the time one abstains from practicing meditation and the increment of nightmare frequency. Moreover, the types of meditation, categorized as focused attention, open monitoring or combined, did not differ on their effect on nightmare frequency; nevertheless, these types of meditation have been found to mainly promote mindfulness 104 . Future studies should address this question and investigate how the different types of meditative practices affect dream variation and intensity.

Taking the aforementioned findings into account, mindfulness based meditation could potentially be a worthy complementary method in reducing nightmare frequency and distress in both clinical and non-clinical populations. In fact, theories that place nightmare-prone individuals within the differential susceptibility framework support the notion that nightmare sufferers may benefit from emotion regulation strategies, such as mindfulness training, due to the possibility that intense emotions, both positive and negative, may be maladaptive and induce awakenings 105 . This, in addition to the potential relationship of mindfulness and lucid dreaming, which, as discussed, is already suggested as complementary treatment for nightmare disorder, may make mindfulness a great aid for the therapeutic process and/or prevention.

While the present findings endorse the idea of different facets of mindfulness having distinct roles when it comes to their relationship to nightmares or, if combined with previous literature, with dream variation in general, our results should only be taken into account through the prism of the following limitations.

The main limitation is the cross-sectional nature of our studies that precludes causal inferences . As in all entirely questionnaire-based studies, correlations between constructs could in principle be driven by common method variance. Future work, perhaps with physiological measurements during sleep, could address the issue. Nevertheless, our pattern of findings cannot be explained by a global response style, which would likely have influenced the correlations of all the mindfulness subscales rather than specific correlation patterns between facets of mindfulness and dream variables. The congruence with findings of other studies also argues against a strong influence of common method variance.

Moreover, the data we analyzed here were part of bigger surveys that were not built in order to solely investigate the relationships we presented here. As mentioned, the two surveys were separate and conducted by two universities in different countries. In spite of the fact that they were both conducted in English and Study 2 was advertised in international websites, some cultural differences are expected.

Regarding the percentage of participants that experience nightmares once or more times per week, which could indicate elevated nightmare frequency, our studies did not substantially differ to each other (Study 1: 7.6%; Study 2: 13.9%) or other studies (15.8%, 10.11% as reported in Schredl and Göritz 15 and Schredl et al. 106 respectively). It is important to note that these studies are only constituted of samples without a particular interest or engagement to lucid dreaming, unlike Study 2. In any case, even though the findings of the two studies presented here are congruent regarding the relationship of Acceptance and nightmares, we think that the two studies should be compared with caution and critical view. The two samples allowed observations about both more experienced lucid dreamers and meditators (Study 2), as well as relatively naive participants (Study 1), to be made, but they were also differing in dream recall and possibly meditation practice and expertise, which can influence the rest of the interrelated variables. Concerning meditation, we were unable to test for differences, as Study 1 did not include questions about meditation. Furthermore, participants in Study 2 were selected based on their dream recall frequency and were recruited mostly from websites related to lucid dreaming, which may diminish the generalizability of the findings.

Finally, mindfulness is a complex construct and various questionnaires and studies conceptualize it as both unidimensional 7 and multidimensional 52 , 53 . The FMI is an inventory that originally approached mindfulness as a unidimensional construct 56 but a two factor approach is suggested for the shorter 14-item scale 9 , which was used here. Other mindfulness scales have been developed to measure up to five facets of mindfulness 52 , 53 . Future research should take that into account and investigate how the different suggested mindfulness components interact with dreaming experiences.

Experimental studies with naïve participants and behavioral interventions will not only advance our understanding about how mindfulness and its components are related to dream quality, but may also support the implementation of the so far neglected mindfulness-based therapy as a complementary technique to existing nightmare disorder treatments. As mentioned before, frequent nightmares can lead to sleep resistance and can have a severe effect on waking life, substantially reducing quality of life and overall well-being 17 , 18 , 21 . Nevertheless, people seem to be quite reluctant to seek professional help for their nightmares, possibly because they perceive them as “normal” 107 since in some cases they have been experiencing nightmares since childhood 108 or they do not perceive them as a problem worth seeking professional help for. In this regard, mindfulness and acceptance-based self-help interventions might be proven a very effective option for reducing nightmare frequency and distress, as there are evidence that such interventions help with other pathological conditions like depression and anxiety 109 , 110 . Moreover, a stepped care approach integrating mindfulness based prevention and intervention techniques for nightmare prone individuals is likely to appear as a more attractive and accessible method of getting help.

Conclusions

The findings of the two studies presented here support the notion of a negative association between mindfulness and nightmares and extend previous results by suggesting mindful acceptance as the main component related to nightmare frequency and distress. Furthermore, practicing meditation and/or lucid dreaming induction techniques appears to be inversely related to nightmare frequency and in the latter case also nightmare distress. Longitudinal experimental studies further investigating the aforementioned findings would be meaningful in order to understand the complexity of dispositional mindfulness and its association to dream variation, as well as inaugurate causal relationships, which can contribute to the refinement of prevention and intervention techniques used in the treatment of nightmare disorder.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.

American Academy of Sleep Medicine (AASM). International Classification of Sleep Disorders—Third Edition. ICSD‐3 (Darien, IL: AASM, 2014).

Picchioni, D. et al. Nightmares as a coping mechanism for stress. Dreaming 12 , 155–169. https://doi.org/10.1023/A:1020118425588 (2002).

Article   Google Scholar  

Spoormaker, V. I., Schredl, M. & van den Bout, J. Nightmares. From anxiety symptom to sleep disorder. Sleep Med. Rev. 10 , 19–31. https://doi.org/10.1016/j.smrv.2005.06.001 (2006).

Article   PubMed   Google Scholar  

Chiesa, A. & Serretti, A. Mindfulness-based stress reduction for stress management in healthy people: A review and meta-analysis. J. altern. Complement. Med. 15 , 593–600. https://doi.org/10.1089/acm.2008.0495 (2009).

Virgili, M. Mindfulness-based interventions reduce psychological distress in working adults. A meta-analysis of intervention studies. Mindfulness 6 , 326–337. https://doi.org/10.1007/s12671-013-0264-0 (2015).

Shallcross, A. J., Visvanathan, P. D., Sperber, S. H. & Duberstein, Z. T. Waking up to the problem of sleep. Can mindfulness help? A review of theory and evidence for the effects of mindfulness for sleep. Curr. Opin. Psychol. 28 , 37–41. https://doi.org/10.1016/j.copsyc.2018.10.005 (2019).

Brown, K. W. & Ryan, R. M. The benefits of being present. Mindfulness and its role in psychological well-being. J. Personal. Soc. Psychol. 84 , 822–848. https://doi.org/10.1037/0022-3514.84.4.822 (2003).

Zollars, I., Poirier, T. I. & Pailden, J. Effects of mindfulness meditation on mindfulness, mental well-being, and perceived stress. Curr. Pharm. Teach. Learn. 11 , 1022–1028. https://doi.org/10.1016/j.cptl.2019.06.005 (2019).

Kohls, N., Sauer, S. & Walach, H. Facets of mindfulness—Results of an online study investigating the Freiburg mindfulness inventory. Personal. Individ. Differ. 46 , 224–230. https://doi.org/10.1016/j.paid.2008.10.009 (2009).

Rak, M., Beitinger, P., Steiger, A., Schredl, M. & Dresler, M. Increased lucid dreaming frequency in narcolepsy. Sleep 38 , 787–792. https://doi.org/10.5665/sleep.4676 (2015).

Article   PubMed   PubMed Central   Google Scholar  

Stumbrys, T., Erlacher, D. & Malinowski, P. Meta-awareness during day and night. Imagin. Cogn. Personal. 34 , 415–433. https://doi.org/10.1177/0276236615572594 (2015).

Simor, P., Köteles, F., Sándor, P., Petke, Z. & Bódizs, R. Mindfulness and dream quality. The inverse relationship between mindfulness and negative dream affect. Scand. J. Psychol. 52 , 369–375. https://doi.org/10.1111/j.1467-9450.2011.00888.x (2011).

Carmody, J. & Baer, R. A. Relationships between mindfulness practice and levels of mindfulness, medical and psychological symptoms and well-being in a mindfulness-based stress reduction program. J. Behav. Med. 31 , 23–33. https://doi.org/10.1007/s10865-007-9130-7 (2008).

Schredl, M. Nightmare frequency and nightmare topics in a representative German sample. Eur. Arch. Psychiatry Clin. Neurosci. 260 , 565–570. https://doi.org/10.1007/s00406-010-0112-3 (2010).

Schredl, M. & Göritz, A. S. Nightmare themes. An online study of most recent nightmares and childhood nightmares. J. Clin. Sleep Med. 14 , 465–471. https://doi.org/10.5664/jcsm.7002 (2018).

Belicki, K. Nightmare frequency versus nightmare distress. Relations to psychopathology and cognitive style. J. Abnorm. Psychol. 101 , 592–597. https://doi.org/10.1037/0021-843X.101.3.592 (1992).

Article   CAS   PubMed   Google Scholar  

Aurora, R. N. et al. Best practice guide for the treatment of nightmare disorder in adults. J. Clin. Sleep Med. 6 , 389–401. https://doi.org/10.5664/jcsm.27883 (2010).

Morgenthaler, T. I. et al. Position paper for the treatment of nightmare disorder in adults. An American academy of sleep medicine position paper. J. Clin. Sleep Med. 14 , 1041–1055. https://doi.org/10.5664/jcsm.7178 (2018).

Nielsen, T. A. et al. Development of disturbing dreams during adolescence and their relation to anxiety symptoms. Sleep 23 , 727–736. https://doi.org/10.1093/sleep/23.6.1 (2000).

Tanskanen, A. et al. Nightmares as predictors of suicide. Sleep 24 , 844–847. https://doi.org/10.1093/sleep/24.7.845 (2001).

Zadra, A. & Donderi, D. C. Nightmares and bad dreams. Their prevalence and relationship to well-being. J. Abnorm. Psychol. 109 , 273–281. https://doi.org/10.1037/0021-843X.109.2.273 (2000).

Agargun, M. Y. et al. Nightmares, suicide attempts, and melancholic features in patients with unipolar major depression. J. Affect. Disord. 98 , 267–270. https://doi.org/10.1016/j.jad.2006.08.005 (2007).

Besiroglu, L., Agargun, M. Y. & Inci, R. Nightmares and terminal insomnia in depressed patients with and without melancholic features. Psychiatry Res. 133 , 285–287. https://doi.org/10.1016/j.psychres.2004.12.001 (2005).

Marinova, P. et al. Nightmares and suicide. Predicting risk in depression. Psychiatria Danub. 26 , 159–164 (2014).

Google Scholar  

Sjöström, N., Hetta, J. & Waern, M. Persistent nightmares are associated with repeat suicide attempt. A prospective study. Psychiatry Res. 170 , 208–211. https://doi.org/10.1016/j.psychres.2008.09.006 (2009).

Nadorff, M. R., Nazem, S. & Fiske, A. Insomnia symptoms, nightmares, and suicidal ideation in a college student sample. Sleep 34 , 93–98. https://doi.org/10.1093/sleep/34.1.93 (2011).

Sandman, N. et al. Nightmares as predictors of suicide. An extension study including war veterans. Sci. Rep. 7 , 44756. https://doi.org/10.1038/srep44756 (2017).

Article   CAS   PubMed   PubMed Central   ADS   Google Scholar  

DeViva, J. C., Zayfert, C. & Mellman, T. A. Factors associated with insomnia among civilians seeking treatment for PTSD. An exploratory study. Behav. Sleep Med. 2 , 162–176. https://doi.org/10.1207/s15402010bsm0203_5 (2004).

Rousseau, P. F. et al. Sleep parameters improvement in PTSD soldiers after symptoms remission. Sci. Rep. 11 , 8873. https://doi.org/10.1038/s41598-021-88337-x (2021).

Zayfert, C. & DeViva, J. C. Residual insomnia following cognitive behavioral therapy for PTSD. J. trauma. Stress 17 , 69–73. https://doi.org/10.1023/B:JOTS.0000014679.31799.e7 (2004).

Gieselmann, A. et al. Aetiology and treatment of nightmare disorder. State of the art and future perspectives. J. Sleep Res. 28 , e12820. https://doi.org/10.1111/jsr.12820 (2019).

de Macêdo, T. C. F., Ferreira, G. H., de Almondes, K. M., Kirov, R. & Mota-Rolim, S. A. My dream, my rules. Can lucid dreaming treat nightmares?. Front. Psychol. 10 , 2618. https://doi.org/10.3389/fpsyg.2019.02618 (2019).

Spoormaker, V. I. & van den Bout, J. Lucid dreaming treatment for nightmares. A pilot study. Psychother. Psychosom. 75 , 389–394. https://doi.org/10.1159/000095446 (2006).

Schädlich, M. & Erlacher, D. Applications of lucid dreams. An online study https://doi.org/10.11588/IJODR.2012.2.9505 (2012).

Belicki, K. The relationship of nightmare frequency to nightmare suffering with implications for treatment and research. Dreaming 2 , 143–148. https://doi.org/10.1037/h0094355 (1992).

Schredl, M. & Goeritz, A. S. Nightmare frequency and nightmare distress. Socio-demographic and personality factors. Sleep Sci. 12 , 178–184. https://doi.org/10.5935/1984-0063.20190080 (2019).

Levin, R., Fireman, G., Spendlove, S. & Pope, A. The relative contribution of affect load and affect distress as predictors of disturbed dreaming. Behav. Sleep Med. https://doi.org/10.1080/15402002.2011.583905 (2011).

Stumbrys, T. & Erlacher, D. Inner ghosts. Encounters with threatening dream characters in lucid dreams. Dreaming 27 , 40–48. https://doi.org/10.1037/drm0000043 (2017).

Stumbrys, T. & Erlacher, D. Mindfulness and lucid dream frequency predicts the ability to control lucid dreams. Imagin. Cogn. Personal. 36 , 229–239. https://doi.org/10.1177/0276236616683388 (2017).

Hess, G., Schredl, M. & Goritz, A. S. Lucid dreaming frequency and the big five personality factors. Imagin. Cogn. Personal. 36 , 240–253. https://doi.org/10.1177/0276236616648653 (2017).

Schredl, M. & Erlacher, D. Lucid dreaming frequency and personality. Personal. Individ. Differ. 37 , 1463–1473. https://doi.org/10.1016/j.paid.2004.02.003 (2004).

Spadafora, A. & Hunt, H. T. The multiplicity of dreams. Cognitive-affective correlates of lucid, archetypal, and nightmare dreaming. Percep. Motor Skills 71 , 627–644. https://doi.org/10.2466/pms.1990.71.2.627 (1990).

Article   CAS   Google Scholar  

Stepansky, R. et al. Austrian dream behaviour. Results of a representative population survey. Dreaming 8 , 23–30. https://doi.org/10.1023/B:DREM.0000005912.77493.d6 (1998).

Galvin, F. The boundary characteristics of lucid dreamers. Psychiatric journal of the University of Ottawa Revue de psychiatrie de l’Universite d’Ottawa 15 , 73–78 (1990).

CAS   PubMed   Google Scholar  

Wolpin, M., Marston, A., Randolph, C. & Clothier, A. Individual difference correlates of reported lucid dreaming frequency and control. J. Ment. Imag. 16 , 231–236 (1992).

Keng, S.-L., Smoski, M. J. & Robins, C. J. Effects of mindfulness on psychological health. A review of empirical studies. Clin. Psychol. Rev. 31 , 1041–1056. https://doi.org/10.1016/j.cpr.2011.04.006 (2011).

Creswell, J. D., Lindsay, E. K., Villalba, D. K. & Chin, B. Mindfulness training and physical health. Mechanisms and outcomes. Psychosom. Med. 81 , 224–232. https://doi.org/10.1097/PSY.0000000000000675 (2019).

Baer, R. A. Mindfulness training as a clinical intervention. A conceptual and empirical review. Clin. Psychol. Sci. Pract. 10 , 125–143. https://doi.org/10.1093/clipsy.bpg015 (2003).

Marlatt, G. A. & Kristeller, J. L. in Integrating Spirituality into Treatment: Resources for Practitioners (ed Miller, W. R.) 67–84 (American Psychological Association, Washington, 1999).

Hofmann, S. G., Sawyer, A. T., Witt, A. A. & Oh, D. The effect of mindfulness-based therapy on anxiety and depression. A meta-analytic review. J. Consult. Clin. Psychol. 78 , 169–183. https://doi.org/10.1037/a0018555 (2010).

Cardaciotto, L., Herbert, J. D., Forman, E. M., Moitra, E. & Farrow, V. The assessment of present-moment awareness and acceptance. The Philadelphia Mindfulness Scale. Assessment 15 , 204–223. https://doi.org/10.1177/1073191107311467 (2008).

Baer, R. A., Smith, G. T. & Allen, K. B. Assessment of mindfulness by self-report. The Kentucky inventory of mindfulness skills. Assessment 11 , 191–206. https://doi.org/10.1177/1073191104268029 (2004).

Baer, R. A. et al. Construct validity of the five facet mindfulness questionnaire in meditating and nonmeditating samples. Assessment 15 , 329–342. https://doi.org/10.1177/1073191107313003 (2008).

Bishop, S. R. et al. Mindfulness. A proposed operational definition. Clin. Psychol. Sci. Pract. 11 , 230–241. https://doi.org/10.1093/clipsy.bph077 (2004).

Simione, L., Raffone, A. & Mirolli, M. Acceptance, and not its interaction with attention monitoring, increases psychological well-being. Testing the monitor and acceptance theory of mindfulness. Mindfulness 12 , 1398–1411. https://doi.org/10.1007/s12671-021-01607-7 (2021).

Walach, H., Buchheld, N., Buttenmüller, V., Kleinknecht, N. & Schmidt, S. Measuring mindfulness—the Freiburg Mindfulness Inventory (FMI). Personal. Individ. Differ. 40 , 1543–1555. https://doi.org/10.1016/j.paid.2005.11.025 (2006).

Hobson, J. A. REM sleep and dreaming. Towards a theory of protoconsciousness. Nat. Rev. Neurosci. 10 , 803–813. https://doi.org/10.1038/nrn2716 (2009).

Dresler, M. et al. Neural correlates of consciousness—insights from sleep imaging (Eighth Göttingen Meeting of the German Neuroscience Society, 2009). Available at https://www.nwg-info.de/sites/nwg-info.de/files/media/pdf/conference/Proceedings_Goettingen2009.pdf .

Schooler, J. W. Re-representing consciousness. Dissociations between experience and meta-consciousness. Trends Cogn. Sci. 6 , 339–344. https://doi.org/10.1016/S1364-6613(02)01949-6 (2002).

Kahan, T. L. in Dreams. A Reader on Religious, Cultural, and Psychological Dimensions of Dreaming (ed Bulkeley, K.) 333–360 (Palgrave Macmillan US, New York, s.l., 2001).

Hobson, A. & Voss, U. A mind to go out of. Reflections on primary and secondary consciousness. Conscious. Cogn. 20 , 993–997. https://doi.org/10.1016/j.concog.2010.09.018 (2011).

Filevich, E., Dresler, M., Brick, T. R. & Kühn, S. Metacognitive mechanisms underlying lucid dreaming. J. Neurosci. 35 , 1082–1088. https://doi.org/10.1523/JNEUROSCI.3342-14.2015 (2015).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Dresler, M. et al. Volitional components of consciousness vary across wakefulness, dreaming and lucid dreaming. Front. Psychol. 4 , 987. https://doi.org/10.3389/fpsyg.2013.00987 (2014).

Jankowski, T. & Holas, P. Metacognitive model of mindfulness. Conscious. Cogn. 28 , 64–80. https://doi.org/10.1016/j.concog.2014.06.005 (2014).

Hussain, D. Meta-cognition in mindfulness. A conceptual analysis. Psychol. Thought 8 , 132–141. https://doi.org/10.5964/psyct.v8i2.139 (2015).

Solem, S., Thunes, S. S., Hjemdal, O., Hagen, R. & Wells, A. A metacognitive perspective on mindfulness. An empirical investigation. BMC Psychol. 3 , 1–10. https://doi.org/10.1186/s40359-015-0081-4 (2015).

Mrazek, M. D., Smallwood, J. & Schooler, J. W. Mindfulness and mind-wandering. Finding convergence through opposing constructs. Emotion 12 , 442–448. https://doi.org/10.1037/a0026678 (2012).

Kang, Y., Gruber, J. & Gray, J. R. Mindfulness and de-automatization. Emot. Rev. 5 , 192–201. https://doi.org/10.1177/1754073912451629 (2012).

Rahl, H. A., Lindsay, E. K., Pacilio, L. E., Brown, K. W. & Creswell, J. D. Brief mindfulness meditation training reduces mind wandering. The critical role of acceptance. Emotion 17 , 224–230. https://doi.org/10.1037/emo0000250 (2017).

Bennike, I. H., Wieghorst, A. & Kirk, U. Online-based mindfulness training reduces behavioral markers of mind wandering. J. Cogn. Enhanc. 1 , 172–181. https://doi.org/10.1007/s41465-017-0020-9 (2017).

Creswell, J. D., Way, B. M., Eisenberger, N. I. & Lieberman, M. D. Neural correlates of dispositional mindfulness during affect labeling. Psychosom. Med. 69 , 560–565. https://doi.org/10.1097/PSY.0b013e3180f6171f (2007).

Baird, B., Riedner, B. A., Boly, M., Davidson, R. J. & Tononi, G. Increased lucid dream frequency in long-term meditators but not following MBSR training. Psychol. Conscious. 6 , 40–54. https://doi.org/10.1037/cns0000176 (2019).

Gackenbach, J., Cranson, R. & Alexander, C. Lucid dreaming, witnessing dreaming, and the transcendental meditation technique. A developmental relationship. Lucidity Lett. 5 (1986).

Hunt, H. T. & Ogilvie, R. D. in Conscious Mind, Sleeping Brain. Perspectives on Lucid Dreaming (eds Gackenbach, J. & LaBerge, S.) 389–417 (Springer New York, Boston, MA, 1988).

Sparrow, G. S., Thurston, M. & Carlson, R. Dream reliving and meditation as a way to enhance reflectiveness and constructive engagement in dreams. Int. J. Dream Res. 10 , 84–93. https://doi.org/10.11588/ijodr.2013.2.10151 (2013).

Malinowski, P. Mindfulness as psychological dimension. Concepts and applications. Ir. J. Psychol. 29 , 155–166. https://doi.org/10.1080/03033910.2008.10446281 (2008).

Stumbrys, T., Erlacher, D., Johnson, M. & Schredl, M. The phenomenology of lucid dreaming. An online survey. Am. J. Psychol. 127 , 191–204. https://doi.org/10.5406/amerjpsyc.127.2.0191 (2014).

Sedlmeier, P. et al. The psychological effects of meditation. A meta-analysis. Psychol. Bull. 138 , 1139–1171. https://doi.org/10.1037/a0028168 (2012).

Sedlmeier, P., Loße, C. & Quasten, L. C. Psychological effects of meditation for healthy practitioners. An update. Mindfulness 9 , 371–387. https://doi.org/10.1007/s12671-017-0780-4 (2018).

Brisbon, N. M. & Lachman, M. E. Dispositional mindfulness and memory problems. The role of perceived stress and sleep quality. Mindfulness 8 , 379–386. https://doi.org/10.1007/s12671-016-0607-8 (2017).

Gong, H. et al. Mindfulness meditation for insomnia. A meta-analysis of randomized controlled trials. J. Psychosom. Res. 89 , 1–6. https://doi.org/10.1016/j.jpsychores.2016.07.016 (2016).

Pattanashetty, R. et al. Practitioners of vipassana meditation exhibit enhanced slow wave sleep and REM sleep states across different age groups. Sleep Biol. Rhythms 8 , 34–41. https://doi.org/10.1111/j.1479-8425.2009.00416.x (2010).

Simione, L., Raffone, A. & Mirolli, M. Stress as the missing link between mindfulness, sleep quality, and well-being. A cross-sectional study. Mindfulness 11 , 439–451. https://doi.org/10.1007/s12671-019-01255-y (2020).

Domhoff, G. W. Finding Meaning in Dreams: A Quantitative Approach (Plenum Press, 1996).

Book   Google Scholar  

Pesant, N. & Zadra, A. Dream content and psychological well-being. A longitudinal study of the continuity hypothesis. J. Clin. Psychol. 62 , 111–121. https://doi.org/10.1002/jclp.20212 (2006).

Serpe, A. & DeCicco, T. L. An investigation into anxiety and depression in dream imagery. The issue of co-morbidity. Int. J. Dream Res. 13 , 82–89. https://doi.org/10.11588/ijodr.2020.1.68130 (2020).

Miller, N. J., DeCicco, T. L., Dale, A. L. & Murkar, A. Assessing the effects of meditation on dream imagery, depression and anxiety. Int. J. Dream Res. 8 , 99–104. https://doi.org/10.11588/ijodr.2015.2.18702 (2015).

Sikka, P., Pesonen, H. & Revonsuo, A. Peace of mind and anxiety in the waking state are related to the affective content of dreams. Sci. Rep. 8 , 12762. https://doi.org/10.1038/s41598-018-30721-1 (2018).

Schredl, M., Stumbrys, T. & Erlacher, D. Dream recall, nightmare frequency, and spirituality. Dreaming 26 , 1–9. https://doi.org/10.1037/drm0000015 (2016).

Hill, C. L. M. & Updegraff, J. A. Mindfulness and its relationship to emotional regulation. Emotion 12 , 81–90. https://doi.org/10.1037/a0026355 (2012).

Brown, K. W., Goodman, R. J. & Inzlicht, M. Dispositional mindfulness and the attenuation of neural responses to emotional stimuli. Soc. Cogn. Affect. Neurosci. 8 , 93–99. https://doi.org/10.1093/scan/nss004 (2013).

Broderick, P. C. Mindfulness and coping with dysphoric mood. Contrasts with rumination and distraction. Cogn. Ther. Res. 29 , 501–510. https://doi.org/10.1007/s10608-005-3888-0 (2005).

Schredl, M. Reliability and stability of a dream recall frequency scale. Percept. Motor Skills 98 , 1422–1426. https://doi.org/10.2466/pms.98.3c.1422-1426 (2004).

Stumbrys, T., Erlacher, D. & Schredl, M. Reliability and stability of lucid dream and nightmare frequency scales. Int. J. Dream Res. https://doi.org/10.11588/IJODR.2013.2.11137 (2013).

Schredl, M., Berres, S., Klingauf, A., Schellhaas, S. & Göritz, A. S. The Mannheim Dream Questionnaire (MADRE). Retest reliability, age and gender effects. Int. J. Dream Res. https://doi.org/10.11588/ijodr.2014.2.16675 (2014).

Leiner, D. J. SoSci Survey (2019).

The jamovi project. jamovi (2021).

Snyder, T. J. & Gackenbach, J. in Conscious Mind, Sleeping Brain. Perspectives on Lucid Dreaming (eds Gackenbach, J. & LaBerge, S.) 221–259 (Springer New York, Boston, MA, 1988).

Cash, M. & Whittingham, K. What facets of mindfulness contribute to psychological well-being and depressive, anxious, and stress-related symptomatology?. Mindfulness 1 , 177–182. https://doi.org/10.1007/s12671-010-0023-4 (2010).

Vujanovic, A. A., Youngwirth, N. E., Johnson, K. A. & Zvolensky, M. J. Mindfulness-based acceptance and posttraumatic stress symptoms among trauma-exposed adults without axis I psychopathology. J. Anxiety Disord. 23 , 297–303. https://doi.org/10.1016/j.janxdis.2008.08.005 (2009).

Wahbeh, H., Lu, M. & Oken, B. Mindful awareness and non-judging in relation to posttraumatic stress disorder symptoms. Mindfulness 2 , 219–227. https://doi.org/10.1007/s12671-011-0064-3 (2011).

Nielsen, T. & Levin, R. Nightmares. A new neurocognitive model. Sleep Med. Rev. 11 , 295–310. https://doi.org/10.1016/j.smrv.2007.03.004 (2007).

Schredl, M. Effects of state and trait factors on nightmare frequency. Eur. Arch. Psychiatry Clin. Neurosci. 253 , 241–247. https://doi.org/10.1007/s00406-003-0438-1 (2003).

Cebolla, A. et al. Exploring relations among mindfulness facets and various meditation practices. Do they work in different ways? Do they work in different ways?. Conscious. Cogn. 49 , 172–180. https://doi.org/10.1016/j.concog.2017.01.012 (2017).

Carr, M. & Nielsen, T. A novel Differential Susceptibility framework for the study of nightmares. Evidence for trait sensory processing sensitivity. Clin. Psychol. Rev. 58 , 86–96. https://doi.org/10.1016/j.cpr.2017.10.002 (2017).

Schredl, M., Holyba, L., Köllmer, T., Körfer, J. & Proß, A. Nightmare distress, nightmare frequency, and beliefs about nightmares. Int. J. Dream Res. 12 , 60–66. https://doi.org/10.11588/IJODR.2019.2.62531 (2019).

Schredl, M. Seeking professional help for nightmares. A representative study. Eur. J. Psychiatry 27 , 259–264. https://doi.org/10.4321/S0213-61632013000400004 (2013).

Kales, A. et al. Nightmares. Clinical characteristics and personality patterns. Am. J. Psychiatry 137 , 1197–1201. https://doi.org/10.1176/ajp.137.10.1197 (1980).

Cavanagh, K., Strauss, C., Forder, L. & Jones, F. Can mindfulness and acceptance be learnt by self-help? A systematic review and meta-analysis of mindfulness and acceptance-based self-help interventions. Clin. Psychol. Rev. 34 , 118–129. https://doi.org/10.1016/j.cpr.2014.01.001 (2014).

Taylor, H., Strauss, C. & Cavanagh, K. Can a little bit of mindfulness do you good? A systematic review and meta-analyses of unguided mindfulness-based self-help interventions. Clin. Psychol. Rev. 89 , 102078. https://doi.org/10.1016/j.cpr.2021.102078 (2021).

Download references

Acknowledgements

We thank Stephan Weingarten for his contribution in Study 2.

Open Access funding enabled and organized by Projekt DEAL. Open access funding provided by the Open Access Publishing Fund of Philipps-Universität Marburg with support of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation). This article is based upon work from COST Action CA18106, supported by COST (European Cooperation in Science and Technology), and a Vidi grant from the Netherlands Organisation for Scientific Research (NWO). The funder had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.

Author information

These authors contributed equally: Martin Dresler, Kristian Sandberg and Erik M. Mueller.

Authors and Affiliations

Department of Psychology, Philipps University Marburg, Marburg, Germany

Sofia Tzioridou & Erik M. Mueller

Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands

Sofia Tzioridou & Martin Dresler

Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark

Kristian Sandberg

You can also search for this author in PubMed   Google Scholar

Contributions

S.T.: Conceptualization, Methodology, Formal analysis, Investigation, Data Curation, Writing—Original Draft, Visualization, Supervision, Project administration. M.D.: Conceptualization, Methodology, Writing—Review & Editing, Supervision, Project administration, Funding acquisition. K.S.: Conceptualization, Methodology, Formal analysis, Investigation, Data Curation, Writing—Review & Editing, Supervision, Project administration, Funding acquisition. E.M.M.: Conceptualization, Methodology, Writing—Review and Editing, Supervision, Project administration. M.D, K.S. and E.M.M. contributed equally to this work.

Corresponding author

Correspondence to Sofia Tzioridou .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Cite this article.

Tzioridou, S., Dresler, M., Sandberg, K. et al. The role of mindful acceptance and lucid dreaming in nightmare frequency and distress. Sci Rep 12 , 15737 (2022). https://doi.org/10.1038/s41598-022-19624-4

Download citation

Received : 27 January 2022

Accepted : 31 August 2022

Published : 21 September 2022

DOI : https://doi.org/10.1038/s41598-022-19624-4

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

By submitting a comment you agree to abide by our Terms and Community Guidelines . If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Quick links

  • Explore articles by subject
  • Guide to authors
  • Editorial policies

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

research paper about lucid dream

Subscribe or renew today

Every print subscription comes with full digital access

Science News

Here’s what lucid dreamers might tell us about our sleeping minds.

Dreams are one of the most universal yet elusive human experiences

illustration of a person wearing pajamas flying through the air with blue a pink hues

Most people rarely lucid dream. But some people can do it regularly and even gain control over these alternate realities.

RUNE FISKER

Share this:

By Maria Temming

August 27, 2023 at 9:00 am

When Christopher Mazurek realizes he’s dreaming, it’s always the small stuff that tips him off.

The first time it happened, Mazurek was a freshman at Northwestern University in Evanston, Ill. In the dream, he found himself in a campus dining hall. It was winter, but Mazurek wasn’t wearing his favorite coat.

“I realized that, OK, if I don’t have the coat, I must be dreaming,” Mazurek says. That epiphany rocked the dream like an earthquake. “Gravity shifted, and I was flung down a hallway that seemed to go on for miles,” he says. “My left arm disappeared, and then I woke up.”

Most people rarely if ever realize that they’re dreaming while it’s happening, what’s known as lucid dreaming. But some enthusiasts have cultivated techniques to become self-aware in their sleep and even wrest some control over their dream selves and settings. Mazurek, 24, says that he’s gotten better at molding his lucid dreams since that first whirlwind experience, sometimes taking them as opportunities to try flying or say hi to deceased family members.

Other lucid dreamers have used their personal virtual realities to plumb their subconscious minds for insights or feast on junk food without real-world consequences. But now, scientists have a new job for lucid dreamers: to explore their dreamscapes and report out in real time.

Dream research has traditionally relied on reports collected after someone wakes up. But people often wake with only spotty, distorted memories of what they dreamed. The dreamers can’t say exactly when events occurred, and they certainly can’t tailor their dreams to specific scientific studies.

Gravity shifted, and I was flung down a hallway that seemed to go on for miles.… My left arm disappeared, and then I woke up. Christopher Mazurek

A photo of Christopher Mazurek during a lucid dream study

“The special thing about lucid dreaming is that you can get even closer to dream content and in a much more controlled and systematic fashion,” says Martin Dresler, a cognitive neuroscientist at the Donders Institute in Nijmegen, Netherlands.

Lucid dreamers who can perform assigned tasks and communicate with researchers during a dream open up tantalizing opportunities to study an otherwise untouchable realm. They are like the astronauts of the dream world, serving as envoys to the mysterious inner spaces created by slumbering minds.

So far, tests in very small groups of lucid dreamers suggest that the strange realities we visit in sleep may be experienced more like the real world than imagined ones. With more emissaries enlisted, researchers hope to probe how sleeping brains construct their elaborate, often bizarre plots and set pieces. Besides satisfying age-old curiosity, this work may point to new ways to treat nightmares. Lucid dream studies could also offer clues about how dreams contribute to creativity, regulating emotions or other cognitive jobs — helping solve the grand mystery of why we dream.

But there are still a lot of problems to solve before lucid dreaming research can really take off. Chief among them is that very few dreamers can become lucid on demand in the lab. Those who can often struggle to do scientists’ bidding or communicate with the waking world. Pinpointing the best techniques to give more people more lucid dreams may assuage those issues. But even if it does, not all scientists agree on what lucid dreams can tell us about the far more common, nonlucid kind.

Are lucid dreams real?

Tales of lucid dreams date back to antiquity. Aristotle may have been the first to mention them in Western literature in his treatise On Dreams . “Often when one is asleep,” he wrote, “there is something in consciousness which declares that what then presents itself is but a dream.”

If Aristotle had lucid dreams often, though, he was probably an outlier. Only about half of people say they’ve ever had a lucid dream , while a mere 1 percent or so say they lucid dream multiple times a week. Modern enthusiasts use various techniques to boost their likelihood of lucid dreaming — such as repeatedly telling themselves before bedtime that they will have a lucid dream, or making a habit of checking whether they’re awake several times a day in the hopes that this routine carries over into their dreams, where a self-check may help them realize they’re asleep. But those practices don’t guarantee lucidity.

The rarity of lucid dreaming may be why modern science took some convincing that it’s even real. For millennia, lucid dreamers’ own testimonies were the only evidence that someone could be self-aware while catching z’s. Some scientists wondered if so-called lucid dreams were just brief waking hallucinations between bouts of sleep.

But within the last few decades, experiments have offered proof that lucid dreams are truly what they seem. It turns out, when someone in a dream purposely sweeps their gaze all the way left, then all the way right, their eyes can match those movements behind closed lids in real life. These motions, measured by electrodes near the eyes, stand out from the smaller optical jitters typical of REM sleep, when most lucid dreams happen. This gives dreamers a crude way to signal they’ve become lucid or send other messages to the outside world ( SN: 9/19/81, p. 183 ). Meanwhile, brain waves and muscle paralysis throughout the rest of the body confirm that the dreamer is indeed asleep.

Eyes on eye movements

A person’s eyes can smoothly track left and right movements when they are awake or in a lucid dream. But when someone closes their eyes and tries to imagine tracking that motion, their eyes pan in small jumps, suggesting that lucid dreams are experienced more like waking perception.

three graphs show the direction of eye movement during waking perception, lucid dreaming and imagination

Neuroscientists are just beginning to realize the potential of that line of communication. Lucid dream research “has been enjoying a renaissance over the last decade,” says neuroscientist Tore Nielsen. He directs the Dream & Nightmare Laboratory at the Center for Advanced Research in Sleep Medicine in Montreal. “This renaissance has made it one of the cutting-edge areas of dream study.”

One research team recently deployed experienced lucid dreamers to find out whether dream imagery is more like real-life visuals or imagined ones. While asleep, six lucid dreamers moved their thumbs in either a circle or a line (or both) and traced that motion with their eyes. Participants repeated the same task while awake with their eyes open and in their imaginations with their eyes closed. People’s gazes panned jerkily when they tracked the imagined movements, as though they were viewing something in low resolution. But in dreams, people’s eyes tracked the movements smoothly just as in real life, the team reported in 2018 in Nature Communications .

“It’s been debated really all the way back to the ancient Greeks, are dreams more like imagination, or is it more like perception?” says study coauthor Benjamin Baird, a cognitive psychologist and neuroscientist at the University of Texas at Austin. “The smooth tracking data suggests that, at least in that sense, the imagery is more like perception.”

This and other early experiments offer a taste of what dreamstronauts could teach us. But any conclusions based on just a handful of dreamers have to be taken with a grain of salt. “They’re more like proof-of-concept studies,” says Michelle Carr, a cognitive neuroscientist at the Center for Advanced Research in Sleep Medicine. “It needs to be studied in bigger samples.”

That means finding — or creating — more expert lucid dreamers.

Strategies for lucid dreaming

If you want to have a lucid dream, there are a few strategies you can use to up your chances. Besides regularly questioning whether you’re awake and setting an intention before bed to become lucid, you can keep a dream diary. Getting familiar with common characters, events or themes in your dreams may help you recognize when you’re dreaming. Some aspiring lucid dreamers also use a tactic called “wake-back-to-bed.” They wake up extremely early in the morning, stay up for a while, then get more shut-eye. That jolt of alertness right before tumbling back into REM sleep may help them become lucid in a dream.

Such techniques can be hit-or-miss, though. And data on their effectiveness are still pretty murky, Baird says. One study with about 170 Australians, for instance, suggested that checking if you’re awake, setting an intention to become lucid and doing wake-back-to-bed all together can increase your odds of lucid dreaming . But it wasn’t as clear if using just one or two of those practices worked.

Investigations by Baird and others have shown that the supplement galantamine promotes lucid dreaming , probably by fiddling with neurotransmitters involved in REM sleep. But galantamine can be saddled with side effects such as nausea. And although lucidity itself does not appear to spoil sleep quality , the long-term effects of using galantamine are not well-known. “Personally, I wouldn’t be mucking around with my neurotransmitters every night,” Baird says.

In 2020, Carr and colleagues reported that they’d coaxed 14 of 28 nappers to become lucid in the lab — including three people who’d never before lucid dreamed — no drugs necessary. Before falling asleep, participants learned to associate a cue, such as a series of beeps, with self-awareness. Hearing the same sound again while sleeping reminded them to become lucid. Carr is particularly interested in finding out whether lucid dreaming can help people conquer nightmares, but researchers at Northwestern use the sensory cue strategy to get more lucid emissaries to carry out dream tasks for their experiments.

Galantamine as a dream aid

For three nights, 121 people combined commonly used strategies for lucid dreaming with one of three doses of galantamine. Those who took higher doses of galantamine were more likely to have lucid dreams.

Effect of galantamine dose on likelihood of lucid dreaming

graph showing the effect of galantamine dose in milligrams on likelihood of lucid dreaming, measured by the percentage of study participants who reported at least one lucid dream

“Our method is kind of a shortcut,” says Northwestern cognitive neuroscientist Ken Paller. It doesn’t require a lot of mental training or the grueling sleep interruptions that some other lucid dreaming techniques do.

Another shortcut for researchers is to recruit dreamers from a special slice of the population: people with narcolepsy, who are liable to fall asleep suddenly during the day.

“They’re just champions at lucid dreams,” says Isabelle Arnulf, a sleep neurologist who heads the sleep disorders clinic at Pitie-Salpetriere University Hospital in Paris.

In 2018, Arnulf’s team reported a study where 18 of 21 narcolepsy patients signaled lucidity during lab naps . Even with those impressive numbers, a couple of lucid nappers still couldn’t control their dreams well enough to complete their assignment: to do something in a dream that made them briefly stop breathing, such as swimming underwater or speaking. One said after waking that they’d simply forgotten to stop breathing while diving off a cliff, while another said they tried to speak but couldn’t get any words out.

Staying lucid and successfully wrangling dream scenarios present challenges for lucid dreamers — and the scientists relying on them. In one study, lucid dreamers instructed to fill a dream room with objects, such as a clock and a rubber snake, ran into problems ; the clock spun wildly, or the snake slithered away. In another experiment, lucid dreamers asked to practice throwing darts were waylaid by only having pencils to throw or being pelted with darts by a nasty doll.

“It’s a lot harder than just passively lucid dreaming in your bed,” says Mazurek, who has participated in several lucid dream studies at Northwestern. “You realize, ‘OK, I have to stabilize the dream. I have to remember what the task is. I have to do the task without the dream falling apart.’ ”

Missions to the moon may be hard, but at least astronauts don’t have to worry about forgetting who or where they are, or their spaceship suddenly turning into a banana.

Despite these challenges, lucid dream expeditions are forging ahead — and fast. In fact, an international crew of dreamfarers, including Mazurek, recently embarked on their most ambitious mission yet.

An illustration of a patient lucid dreaming surrounded by scientists and charts. Swirling above are another depiction of the patient holding a clock with snakes and other dream figures swirling around.

Real-time dream science

When it comes to getting on-the-ground data, interviewing dreamers in real time is, well, the dream. Instead of just sitting back and watching dreamers do various activities, researchers could ask these agents about their experiences moment to moment, painting the realm of dreams in sharper detail than ever before.

“Reports of dreamed sensations, [such as] tasting certain foods, can be compared with those of actual sensations,” Nielsen says. “Similarly, one could test whether sexual pleasure, certain sounds or other types of experiences are accurately simulated.” These details, he says, might help “probe the limits and mechanisms of dream production.”

Karen Konkoly is especially excited about giving people assignments mid-dream. Say researchers want to know how much dreams help with creative problem-solving. If dreamers are assigned a problem before sleep, they’re liable to mull it over as they nod off. “Even if it feels like the lucid dream, maybe it’s really the time as you’re falling asleep that helped you solve the problem,” says Konkoly, a cognitive neuroscientist at Northwestern. Airdropping a puzzle straight into a dream could better isolate the usefulness of that specific part of sleep.

There’s a whole medley of theories about why people dream, from honing skills to tapping into creativity to processing memories or emotions. “But if you can’t control the dream in real time and then study the outcome, then you never know … if the dream is really doing anything,” Konkoly says. So a few years ago, she, Arnulf, Dresler and others decided to find out if people can receive and respond to outside input while dreaming.

Thirty-six people took snoozes at Northwestern, Arnulf’s lab, Dresler’s lab or another lab that was in Germany. Once sleepers signaled that they were lucid, researchers spoke yes-or-no questions or math problems in the sleepers’ ears. Or, for the Germans, lights flashing different colors conveyed math questions in Morse code. Before conking out, dreamers were told to answer whatever questions they received with eye signals or by smiling and frowning.

“Facial muscles are less inhibited than other muscles during REM sleep,” Arnulf explains. Someone smiling in a dream may not make that expression in real life, but electrodes on the face can register tiny corresponding muscle twitches.

Out of 158 attempts to interrogate lucid dreamers, 29 total correct responses came from six different people . Those six ranged from newbie to frequent lucid dreamers, including Mazurek, who heard scientists’ questions while dreaming he was in a Legend of Zelda game. The rest of the attempts yielded five wrong answers, 28 ambiguous ones and 96 nonresponses.

When Konkoly first saw someone correctly answer a question in their sleep, “my first reaction was to not believe it.” But for 26 of those 29 correct responses, a panel of independent sleep experts unanimously agreed that the dreamers were in the throes of REM sleep when they replied. Nearly 400 attempts to reach sleepers who hadn’t signaled lucidity netted a single correct response — bolstering the researchers’ confidence that correct answers from lucid dreamers weren’t flukes. The results appeared in 2021 in Current Biology .

Answering questions during a dream

While dreaming, Christopher Mazurek signaled the outside world by sweeping his eyes left and right. Electrodes on his face recorded those motions. On the graph below, Mazurek’s eye motions that indicate he is lucid appear as three big up-down sweeps. Eye signals answering “2” to researchers’ simple math question appear as two big up-down sweeps.

Lucid dreamer’s eye movements during a mid-dream conversation

graphic showing a lucid dreamer’s eye movements during a mid-dream conversation that lasted 30 seconds

“I was astonished,” says Robert Stickgold, a cognitive neuroscientist at Harvard Medical School who studies dreams but not lucid ones. “I had no question but that these people are in fact listening and are in fact having lucid dreams at the time of the communication — and that opens up all sorts of possibilities.”

Arnulf and others have since asked lucid dreamers to smile or frown as their dreams became more or less pleasant with the goal of understanding how dreamers experience emotion. Another study, not yet published, tracked when lucid dreamers answered or ignored researchers’ questions to see how people tuned in and out of the real world while dreaming. Knowing which signals break the dream-reality barrier could help “uncover the mechanism of the brain’s disconnection from the external world — which is huge,” Baird says. It could even be relevant for other states of unconsciousness, he adds, such as when someone is put under for surgery.

Limits of lucidity

Even if researchers get all the expert lucid dreamers they need to run all their desired experiments, there’s still one major sticking point to this whole field of study.

“The biggest issue is how far can you push these results to dreaming in general,” Stickgold says. Imagine, for instance, that lucid dreamers get better at a skill by practicing it in their dreams. It’s not clear that people who just happen to have normal dreams about doing those activities, without self-awareness, would reap the same rewards. “It’s a little bit like recruiting major league baseball players to give you some baseline data on how far people can throw balls,” Stickgold says.

Existing data do suggest that lucid dreamers may have access to parts of the brain that normal dreamers don’t. The lone case study comparing fMRIs of someone’s lucid and nonlucid REM sleep hints that brain areas linked with self-reflection and working memory are more active during lucidity. But those data come from just one person, and it’s not yet clear how such differences in brain activity would affect the outcomes of lucid dream experiments.

Brain clues to lucid dreams

Functional MRI scans of one sleeper’s brain during lucid and nonlucid sleep showed that some brain areas (highlighted) may be more active during lucid dreams than during normal sleep.

  • The lateral parietal cortex is involved in working memory.
  • The dorsolateral prefrontal cortex and frontopolar cortex are involved in working memory and introspection.
  • Activity near the temporal cortex may make lucid dreams brighter and more detailed than normal dreams.

research paper about lucid dream

Some researchers, including Dresler, resist the idea that lucid dreams are profoundly different from nonlucid ones. “Lucid dreaming is not a strict all-or-nothing phenomenon,” he says, with people often fluttering in and out of awareness. “That suggests that lucid and nonlucid dreaming are in principle something very similar on the neural level and not two completely different animals.”

Perhaps lucidity affects some aspects of the dream experience but not all of them, Baird adds. In terms of how dreams look, he says, “it would be very, very surprising if it was somehow completely different when you become lucid.”

A more thorough inventory of the differences in brain activity between lucid and nonlucid dreams might help settle these questions. But even if lucid dreams don’t represent dreams in general, Nielsen still thinks they’re worth studying. “It is a type of consciousness that has intrigued and amused people for centuries,” he says. “It would be important for science to understand how and why humans have this extraordinary capacity for intentional world simulation.”

More Stories from Science News on Neuroscience

Stacks of long tubes of various lengths are seen. Inside the tubes is a bright purple "filling". This is the long part of a nerve fiber called an axon. Around those fibers are thick tubes colored brownish-gray that form an insulating sheath around the nerve. Some wispy strands of connective tissue lays over some of the tubes. Connective tissue is colored hot pink.

Ancient viruses helped speedy nerves evolve

A baby sits on a white couch reading a book next to a teddy bear.

How do babies learn words? An AI experiment may hold clues

A man's prosthetic hand hovers over metal cubes that he sorted into a red area for hot and blue area for cold. A sensor on the index finger of the prosthetic hand is connected to a box higher up on his arm where the nerve impulses to sense temperature originate. A thermal image on a laptop show that the cubes were sorted correctly.

A new device let a man sense temperature with his prosthetic hand

An image of a brain scan with glowing purple and orange spots that mark amyloid-beta.

Under very rare conditions, Alzheimer’s disease may be transmitted

a close up of a hand with a pen writing

Handwriting may boost brain connections more than typing does

Illustration of a the brain inside a 3-D silouhette of a man's head featuring, in part, the thalamus, which is shown in turquoise.

Electrical brain implants may help patients with severe brain injuries

An illustration of a brain superimposed by brain waves from an EEG

A brain-monitoring device may one day take the guesswork out of anesthesia

A teen looks sadly at a laptop screen in a dark room.

Brain scans give clues to how teens handle pandemic stress

From the nature index.

Subscribers, enter your e-mail address for full access to the Science News archives and digital editions.

Not a subscriber? Become one now .

Is Lucid Dreamless Sleep Really Lucid?

  • Open access
  • Published: 04 November 2022

Cite this article

You have full access to this open access article

  • Adriana Alcaraz-Sánchez   ORCID: orcid.org/0000-0003-4772-7373 1  

2712 Accesses

12 Altmetric

Explore all metrics

Recently, the construct ‘ lucid dreamless sleep’ has been proposed to explain the state of ‘clear light’ described by Tibetan Buddhist traditions, a special state of consciousness during deep sleep in which we’re told to be able to recognise the nature or essence of our mind (Padmasambhava & Gyatrul 2008 ; Ponlop 2006 ; Wangyal 1998 ). To explain the sort of awareness experienced during this state, some authors have appealed to the sort of lucidity acquired during lucid dreaming and suggested a link between both phenomena (Thompson 2014 , 2015 ; Windt 2015a ; Windt et al. 2016 ). Whilst these authors appeal to a non-conceptually mediated form of lucidity, which doesn’t consist of reflective awareness and propositional thought, the question as to whether the state of clear light should be considered a lucid state similar to lucid dreaming still arises. I argue that the concept ‘lucidity’ used to describe this sort of state is imprecise and that two theoretical notions of lucidity should be distinguished. The first one, which I call the technical notion , requires the recognition of the hallucinatory character of my current experience. The second, the broader notion , involves the seeming recognition of being directly acquainted with the phenomenal character of my experience. I spell out these two notions of lucidity and argue that only the latter could apply to the state of clear light sleep.

Similar content being viewed by others

research paper about lucid dream

Good Night and Good Luck: Some Late Thirteenth-Century Philosophers on Activities in and through Dreams

research paper about lucid dream

Ancient Theories

Early modern theories.

Avoid common mistakes on your manuscript.

1 Introduction

While the notion of lucidity might be described in a pre-theoretical sense to allude to a state in which one has rediscovered something forgotten or has gained a certain truth, there’s a specific sense in which the notion is used technically to describe certain conscious states. A paradigmatic case of the application of such a notion of lucidity is that found in the realm of dream and sleep research to describe a particular sort of dream; that in which one realises that one is dreaming while dreaming, commonly known as ‘lucid dreaming’ (henceforth, LD). Such a technical notion draws upon certain intuitions about what lucidity is. In the case of dreaming, lucidity is a state in which one realises that what they took to be reality, or the wakeful world, is indeed a dream. Although this notion of lucidity is used in a technical way to provide a theoretical explanandum of a certain phenomenon, there are different ways in which this notion is accounted for in the literature of dreaming. In turn, those understandings affect how the notion of lucidity, in a technical way, is applied to other conscious states outside dreaming. An example of this is ‘ lucid dreamless sleep’ , a construct that has recently acquired increased attention in the study of the nature of consciousness (see Thompson 2014 ; 2015 ; Windt 2015a ; Windt et al. 2016 ).

The construct of lucid dreamless sleep has been proposed to describe a particular state of awareness during sleep widely reported in contemplative traditions, such as the Dzogchen lineage in Tibetan Buddhism. According to classical Dzogchen teachings, by engaging in certain meditation practices, one can aspire to reach a state of ‘clear light’ during deep sleep (cf. Padmasambhava & Gyatrul 2008 ). The state of clear light is then conceived as a state of consciousness different from any other conscious state such that it lacks thoughts, cognition and perceptual experience (see Olivelle 1998 ). For these contemplative traditions, the state of clear light doesn’t involve an ordinary state of consciousness with a subject-other distinction (Holecek 2016 ; Raveh 2008 )—i.e. an ‘I’ who is aware of ‘something’. Instead, the state of clear light is understood as a state of non-dual awareness, also conceived as “pure awareness” (Wangyal 1998 ) or “bare awareness” (Ponlop 2006 ). Moreover, some commentaries and translations of the original Dzogchen texts refer to it as a state of “luminosity” (Fremantle 2001 ; Ponlop 2006 ) or “clarity” (Rinpoche 2002 ); a state where we’re said to perceive things clearly and recognise the “true” or “fundamental” nature of the mind (Dalai Lama 1996 ; Ponlop 2006 ). During this state, one is able to recognise the qualitative character of the experience, which is taken as an essential and intrinsic aspect of consciousness (MacKenzie 2007 :41). Footnote 1 Thus, there is a sense in which the clear light is understood as a state of phenomenal awareness, inasmuch as there is something it is like to be in such a state (cf. Nikhilananda 1949 ; Thompson 2014 , 2015 ). While one isn’t able to engage in reflective thought while in it, one can be aware of the qualitative aspect of such a state and report it afterwards.

Some authors have attempted to explain the sort of awareness present during the so-called state of ‘the clear light sleep’ by relating it to LD awareness. Evan Thompson ( 2015 ) illustrates the link between LD and the clear light sleep in the following way:

“Whereas lucid dreaming consists in knowing that you’re dreaming, lucid dreamless sleep is said to consist in being able to witness the state of dreamless sleep and recall its phenomenal clarity upon waking up" (p.15, stress added)

While Thompson suggests a link between both phenomena, LD and lucid dreamless sleep, he also notes that the sort of lucidity in the latter doesn’t involve the kind of reflective or higher-order thought traditionally ascribed to LD. Instead, lucid dreamless sleep involves what he regards as “non-conceptual meta-awareness” ( 2015 :1)—a state of meta-awareness that doesn’t involve conceptually mediated representations. Windt ( 2015a ) follows Thompson in conceiving the sort of lucidity occurring during the clear light sleep as a form of “non-conceptually mediated” insight (p.20), or what she takes to be a state involving the feeling of knowing about the nature of one’s ongoing conscious experience (ibid). Both authors also acknowledge that not all instances of awareness during the clear light sleep are instances of lucidity. For instance, Windt suggests how a simpler state of non-lucid awareness could be had, involving a sense of pure temporality or “now” (Windt 2015a , b ). Moreover, these authors describe both non-lucid and lucid cases of the clear light sleep as instances of phenomena they refer to as ‘ dreamless sleep’ —sleep experiences that shouldn’t be regarded as dreaming inasmuch as they don’t involve the experience of a self in a dreamt or simulated world (see Windt et al. 2016 ).

Notwithstanding the extensive conceptual and theoretical work undertaken by Thompson and Windt, there is a way in which the construct of ‘lucid dreamless sleep’ is misleading and requires further clarification. If such a state is considered as dream- less and, thus, isn’t meant to be a state of perception similar to dreaming, can such a state still be conceived as ‘lucid’ in the technical sense of the word used in LD, even if regarded as ‘non-conceptual’? Is this the sort of state that can be lucid in this technical sense? And if not, could the state of lucidity reached during the clear light sleep be considered as ‘lucid’ in a different sense, and if so, what sense would that be? In this paper, I claim that the construct of ‘lucid dreamless sleep’ is imprecise and that further theoretical examination of the notion of lucidity is needed. I start by spelling out the different notions of lucidity used in dream research, and the problems they face. I then put forward a technical account of lucidity aimed at describing a state of minimal lucidity. According to this view, a state of lucidity, in a technical and strict sense, is a state in which one recognises that one’s experience falls short of perception. I then examine how the technical notion of lucidity fits within other similar states, both during dreaming and during wakefulness. Finally, I show how a broader theoretical account of lucidity should be applied if we want to conceptualise dreamless sleep as ‘lucid’. I propose that a state should be considered ‘broadly lucid’ if it involves the seeming recognition that one is directly acquainted with the phenomenal character of the experience.

2 What Makes a Dream State Lucid?

2.1 views on lucidity in lucid dreaming research.

Since the inception of the term ‘lucid dreaming’ by Van Eeden ( 1913 ), LDs are described as those dreams in which one knows that one is dreaming (Gillespie 1983 ; Green 1968 ; LaBerge 1985 ). However, in the literature, we find slightly different characterisations as to what this ‘knowing that one is dreaming’ amounts to. Classical views of this phenomenon portray dream lucidity as a state of reflective awareness, or reflective thought, a state where the dreamer reflects on their current experience and concludes they’re dreaming (Gackenbach & LaBerge 1988 ; Green 1968 ; LaBerge et al. 1981 ; Tart 1979 ; Van Eeden 1913 ). In this respect, classical views of lucidity emphasise how LD involves a state of ‘clarity’ or clear mind closer to that of ordinary wakefulness (LaBerge 1980 ; Tholey 1988 ). Some classical views go further and claim that dream lucidity also involves a phenomenal shift in the experience, phenomenologically regarded as ‘hyperreal’ (Brooks & Vogelsong 1999 ; LaBerge 1985 ; Metzinger 2003 , 2009 ). LD is then conceived as an all-pervading experience different from any ordinary waking state (Tart 1979 , 1984 ). Other classical accounts of lucidity have focused on studying the behaviour associated with the acquisition of lucidity: the capacity for controlling one’s dreamt and/or physical body. Such an approach, usually accepted in experimental research, was initiated with Stephen LaBerge’s eye-signalling method for LD. Footnote 2 For these accounts, lucidity is taken as an operationalised notion that can be tested experimentally with lucid dreamers volitionally performing certain actions in their dreams.

While classical views of lucidity highlight some of the distinctive features of LD, contemporary empirical research indicates that such descriptions of LD only account for certain instances of lucidity and leave many more cases out. First, a wide body of research on dream metacognition shows how the capacity for self-reflectiveness isn’t exclusive to LD. Non-lucid dreamers can also think and reflect on the dream events as well as execute rational thought (Bosinelli 1995 ; Cicogna & Bosinelli 2001 ; Kahan 1994 ; Kahan & LaBerge 1996 , 2011 ). From the evidence presented in these studies, many authors claim that reflective thought while dreaming isn’t a dichotomous phenomenon and moves along a continuum, as it does during waking states (Kahan & LaBerge 2011 ; Mallett et al. 2021 ). Second, LD rarely involves a subject who can fully realise the implications of their dream being a dream, as some classical views claim (Tholey 1988 ). Lucidity lapses are frequent and common in LDs, and thus, the dreamer doesn’t always seem to acknowledge the consequences of their experience being virtually generated (Windt & Voss 2018 ). Moreover, lucidity might be only gained towards certain aspects of the dream but not others. For instance, the dreamer might still take some elements of the dream as real like regarding a dream character to be a real person or believing that actions in the dream impact the waking world (Barrett 1992 ; LaBerge and DeGracia 2000 ). Footnote 3 Third, most LDs don’t involve a phenomenal shift like the experience of the dream as unreal and when they do it’s quite rare (see Voss et al. 2013 ). Thus, the need for a phenomenal shift for a dream to be considered lucid might be unnecessary—one might become lucid in a dream without experiencing their dream phenomenally differently. Footnote 4 Finally, the operationalised definition of LD dreaming in the realm of experimental research seems to only cover certain sorts of LD, namely, those in which the dreamer can control their dreams. However, empirical research reveals the rarity of full-fledged forms of LD, including those which feature dream control (Stumbrys et al. 2014 ). As such, considering only LDs as dreams involving control over dream events, or execution of certain pre-established actions (as instructed by LaBerge’s eye-signalling method) might only cover a subset of LD (see Horton 2020 for a discussion). Footnote 5 Besides, the capacity for controlling one’s dream is a multi-faceted skill which doesn’t only involve executing actions under one’s own will, but also certain components of self-determination, planning, and intention (see Dresler et al. 2014 ). While some components of behaviour and action control are most prominent during LD, they aren’t exclusive from LD and some of those components are also observable to a lower extent during non-LD (Kahan et al. 1997 ; Kozmová & Wolman 2006 ; Wolman & Kozmová, 2007 ).

Given these limitations of classical views of LD to only explain certain LDs, more researchers are shifting towards graded views of lucidity, claiming that dream lucidity isn’t an all-or-nothing phenomenon, but a graded one (Mallett et al. 2021 ; Noreika et al. 2010 ; Stumbrys et al. 2014 ; Windt 2015b ). Graded accounts of lucidity aim at considering the full lucidity spectrum and the variability of lucidity across different LDs. An example of a graded view is that put forward by Windt and Metzinger ( 2007 ) who distinguish between full-fledged forms of lucidity and what they regard as ‘weaker’ ones. According to these authors, the sort of lucidity portrayed by classical views as a state of reflective thought usually refers to a strong form of lucidity, or what they coin “Cognitive” or “C-Lucidity” (p.222)—the capacity to form and apply certain concepts to our current mental state. However, as some empirical research indicates, lucidity in dreaming isn’t always experienced as a state of higher-order awareness, such as the awareness of the content of our state as that of being in a dream state. To explain those cases, these authors appeal to subsymbolic and nonconceptual representations occurring at a subpersonal level—our current conscious state is represented as that of a dream, yet we lack conceptual awareness of our experience as that of a dream (Windt, 2015b :428). According to these authors, in some LDs, the dream is experienced as a dream , yet in a non-propositional and non-conceptual way (Windt and Metzinger 2007 :222). Windt and Metzinger regard these cases as instances of “Attentional” or “A-lucidity” and deem them as forms of “weaker lucidity” (ibid). Other authors like Noreika et al. ( 2010 ) also distinguish amongst different types of lucidity, such as “Emotional” or “E-lucidity” (p.41)—dreams in which the dreamer’s emotional response is appropriate to what would be expected if they knew they were dreaming (i.e. I don’t become scared if I run into a tiger in a dream). More recently, Windt ( 2015b ) has suggested that ‘weaker’ forms of lucidity (or A-lucidity) could be related to the sort of non-conceptual awareness present in epistemic feelings or noetic feelings (Dokic 2012 ; Koriat 2000 ), like the tip-of-the-tongue feeling or feelings of knowing. I’ll later delve into this view but for now, the main point here is that, according to Windt, weaker forms of lucidity might be instances where one has a feeling of knowing that one is dreaming without involving further propositional thought about our current experience (see Windt 2015b : 432). Footnote 6

This shift towards graded views of lucidity has highlighted the variability of lucidity in dreaming which doesn’t always involve a subject with a full recovery of their cognitive capacities or who can fully realise the non-veracity of some elements of their experience. Insofar as the subject is in a state that yields true justified belief about their current state as one of dreaming (to a lesser or higher degree, they know that they’re dreaming), most current dream researchers would regard their experience as a lucid, regardless of whether the dreamer has full conceptual awareness of this fact or a mere feeling of knowing that this is the case (as proposed by Windt and Metzinger). However, some further clarifications as to what that feeling of knowing that one is dreaming amounts to are needed to frame which sort of dreams should be considered minimally lucid. I’ll examine some of the problems arising from a graded view of lucidity, especially when used to distinguish between pre-lucid states or dreams that might lead to lucidity and minimally lucid dreams.

2.2 Disambiguating Between Pre-Lucidity, Weak Lucidity and Minimal Lucidity in Dreaming

The notion of ‘pre-lucidity’ is often used in the dream literature to describe dreams in which the dreamer shows some signs of knowing that their experience is a dream yet fails to classify it as a dream—we might then say that the dreamer fails to become lucid. These signs include wondering or asking oneself if one’s dreaming (Green 1968 ), observing the bizarreness or incongruities of one’s experience (Mallett et al. 2021 ; Sparrow et al. 2013 , 2018 ) or recognising some but not all dream elements as unreal (Barrett 1992 ; Moss 1986 ); all without actually recognising the dream as a dream. However, there is an equivocal sense in which the notion of pre-lucidity has sometimes been used in the literature, thus, leading to the conflation of pre-lucidity with weak or simple forms of lucidity. As the term indicates, pre-lucidity is a state that precedes lucidity, not a state that should count as lucidity.

The conflation between pre-lucidity and weakly lucid states can be seen in various examples found in the literature. For instance, Windt and Metzinger ( 2007 ) illustrate a case of weak lucidity (or A-Lucidity) by quoting a dream where the dreamer becomes lucid in virtue of gaining an awareness of an unreal or odd quality of the experience; in the example given, that the colours perceived in the dream are like no other experienced before (see LaBerge & Rheingold 1990 in Windt and Metzinger 2007 :223).Yet it isn’t clear from the analysis provided by these authors whether the state described is one of (weak) lucidity at all or it’s just an enabling condition that brings about lucidity. If we stick to Windt and Metzinger’s account of weak lucidity, a weakly lucid dream is that in which the dreamer can represent in a non-conceptual manner (or subsymbolically) their state as that of a dream state. There’s a non-propositional way of knowing that one is dreaming. However, Windt and Metzinger regard the dreamer of the previous example as lucid inasmuch as they become self-aware of the qualitative aspect of their experience, in this case, that the colours they’re experiencing are like no other colours ever experienced before. While this fact might be an enabling condition for the dreamer to become lucid, it doesn’t seem that this self-awareness alone can explain lucidity. Moreover, Windt and Metzinger also refer to weak lucidity states as ‘pre-lucid states’ (p.222) raising the question as to whether pre-lucidity should be then considered as a state that precedes lucidity, as a form of lucidity, or as something else. Footnote 7

The problem of disambiguating what should count as “weakly lucid” or “pre-lucid” (i.e. enabling lucidity) is also found in other characterisations of LD as a state of ‘insight’ or ‘metacognitive insight’(see Baird et al. 2019 ; Filevich et al. 2015 ; Voss et al. 2013 ; Voss & Hobson 2015 ; Windt & Voss 2018 ). Some researchers describe LD as “insight into the fact that one is currently dreaming” (Voss & Hobson 2015 :5). However, ‘insight’ is an ill-defined notion and it isn’t always clear what it refers to. As in the case of ‘knowing that one is dreaming’ put forward by classic views of LD to describe dream lucidity, different authors understand differently what this ‘insight’ amounts to. Kühle ( 2015 ) offers an extensive conceptual analysis of this notion and argues that insight can be read in two ways. It can refer to a state of self-knowledge about the fact that one is dreaming, such as a state in which I have knowledge of the content of my state of awareness (i.e. a state of second-order awareness such as the ‘knowledge that p ’). However, it can be read as a state of self-awareness about dreaming which Kühle describes as an instance of knowledge-how, procedural knowledge, or as experiential insight (p.7); there’s no propositional thought such as “this is a dream” that I’m aware of, yet I’m aware of my ongoing state as that of a dream. In this case, what makes me aware of the dream state as a dream is my awareness of the subjective character of my experience—according to Kühle, there’s reflexive awareness of our current state as one of dreaming given in the phenomenal character of our experience. Footnote 8 While Kühle teases apart the different ways in which the notions of insight can be portrayed, it still raises similar questions as to whether awareness of the phenomenal character of my experience as a dreamlike one would count as a case of weak lucidity or just as an enabling condition for lucidity, and thus, a pre-lucid state.

The previous characterisations of how insight about the nature of our current state as one of dreaming can be brought about seem to demand a further explanation as to how lucidity exactly takes place. It seems that merely gaining awareness of the content of the phenomenal character of our experience—even if the content of such is about an experience that seems odd, unreal or dreamlike—isn’t enough for a state to be considered lucid. Such an awareness might be merely an enabling condition for becoming lucid. Windt ( 2015b ) also discusses this issue by presenting a case falling within the borders between pre-lucidity and weak lucidity. In the example brought by Windt, one might have certain feelings of knowing within their dream experience, for instance, by feeling that one knows a dream character or that one knows that one’s dream’s apartment is different from the real one (p.429). Windt describes those feelings of knowing as epistemic or noetic feelings—feelings that represent our current cognitive state in a non-conceptual and non-propositional manner (see Proüst 2014 ). According to Windt, those feelings point towards a non-conceptual representation of my current state as that of a state of dreaming—I know in a non-conceptual way that I’m dreaming. Following on her account of lucidity put forward with Metzinger, Windt describes such an example as an instance of weak or A-lucidity. However, as Windt notes, not any sort of noetic feeling would do to regard this example as an instance of (weak) lucidity; lucidity won’t be brought about by merely having a sense of familiarity with some elements of the dream, but those noetic feelings should “spread to the process of dreaming itself, thus enabling the dreamer to hit on the right explanation of this strange feeling, namely, that all of this is a dream” (p.431). From this remark by Windt, it seems that the condition for a noetic feeling to trigger a state of weak lucidity is a bit more demanding—a state of weak lucidity isn’t a state in which I only have self-knowledge about the phenomenal character of my experience, in this case, realising about a feeling of familiarity within my experience, but my current state needs to be represented as one of dreaming (or a virtually generated one). I will comment on this further in §2.3.

In the next subsection, I put forward a technical account of lucidity aiming at capturing what exactly makes a state minimally lucid by drawing from the different views of lucidity in the literature and by addressing some of the problems that those views face.

2.3 The Technical Account of Lucidity

While graded views of lucidity do consider the full lucidity spectrum, contra classic views which only focus on the top extreme of lucidity, graded views aren’t often able to properly spell out the necessary conditions for a dream to be considered lucid, and thus, what distinguishes non-lucidity from pre-lucidity and minimal lucidity. Here, I put forward a technical account of lucidity drawing from the assumption that lucidity is a graded phenomenon but also by considering what makes a state minimally lucid, contra a non-lucid or pre-lucid state. Following on the descriptions found in the literature, I argue that a lucid state is one in which I recognise the hallucinatory character of my experience, a distinctive feature that is only found during episodes of lucidity, regardless of the degree of lucidity.

Different views of lucid dreaming seem to point to a representational state in which our current state is represented as one lacking perception. Footnote 9 For instance, classical views of lucidity only consider cases in which this representation involves conceptually meditated content—the dream is considered lucid insofar as one correctly categorises their current experience as a ‘dream’. Graded views of lucidity depart from this by arguing that the concept ‘dream’ can be applied afterwards, and thus, doesn’t specify the content of the current experience—one can be lucid in a dream yet lack the concept ‘dream’ or fail to apply that concept at that moment. In this respect, graded views consider cases of non-conceptual awareness and argue that a state can be lucid if it represents our current state as a dream state (or as a state that is hallucinatory or virtually generated), yet this representation isn’t conceptually mediated—I don’t need to possess the concepts that canonically specify the content of my mental state. Thus, we could take a state of non-conceptual awareness to be lucid in the strict sense if the state described is one in which my current state (or a property of my current state) is represented as simulational or as lacking perception. It yields a justified true belief, although it might not be until we wake up that we apply the concept of ‘dreaming’ to that state. We know that we’re dreaming in a non-conceptual way, which could be described as merely having a feeling of knowing that we’re dreaming (as opposed to having a state of propositional knowledge about that fact).

From the different definitions of LD found in the literature, I propose a unified account of minimal lucidity which attempts to assess all the different cases of lucidity. For that, I claim that lucidity, in a technical sense, should be regarded as a state in which I recognise the hallucinatory nature of my current perceptual state. For a dream to be minimally lucid, I must realise that what I took to be reality is indeed a simulation or a hallucinatory experience, and thus, that I’m not currently in perceptual contact with the world. Footnote 10 This proposal isn’t a new one and relies on claims already made in the literature. Several authors assert that the realisation of the hallucinatory character of the current experience by the dreamer is one of the key features of dream lucidity (Noreika et al. 2010 ; Revonsuo 2006 ; Voss & Hobson 2015 ; Windt & Metzinger 2007 ). Footnote 11 Such a feature seems to be crucial for becoming lucid and is maintained across different degrees of dream lucidity, as found by Voss et al. ( 2013 ). From all the above, lucidity, in the technical sense, should be described as the following:

Technical notion of lucidity: A state involving the representation of our current state as one that lacks perceptual contact with the world, or a state that falls short of perception.

Moreover, given the different degrees of lucidity characterised in the literature, we can regard the technical notion of lucidity more strongly or weakly, thus, giving place to different sorts of lucid states:

Strong lucidity : Requires conceptual awareness and categorisation or classification of the dream as a dream.

Weak lucidity : Doesn’t require conceptual awareness, yet it involves non-conceptually representing my state as one of dreaming or a state not amounting to perception.

In the technical sense, a strong LD is a dream in which one categorises and classifies one’s own state of awareness as that of a dream. In that sense, lucidity might involve linguistic or propositional thought, yet doesn’t need to. Note that here I’m only considering those cases of lucidity that are at the bottom end of the spectrum and leave out more full-fledged cases of lucidity which might involve explicit awareness of the content of one’s conscious state, reflective thought or dream control. To a weaker degree, we find LDs where the dreamer still represents their current experience as that of a dream, yet in a non-conceptual manner at a subsymbolic level. Footnote 12 The dreamer might possess the concept ‘dream’ which they might apply upon waking up. The difference in the ‘weaker’ case is that the concept ‘dream’ doesn’t specify the content of the dreamer’s current state of awareness. In a weaker sense, a LD might merely involve a feeling of knowing that one is dreaming. Nevertheless, is crucial to point out that regardless of taking lucidity to a stronger or weaker degree, under the technical account, such a state would only be lucid if it involves a specific sort of content: that of a state that doesn’t consist of perceptual contact with the world. Thus, in the case of LD, the specific content of my conscious state is that of realising that my current experience is simulational (or hallucinatory).

By counting with such a unified account of what minimal lucidity should amount to, we can distinguish better between pre-lucid and minimally lucid states. Under the account I present here, pre-LDs are regarded as a class of non-lucid dreams and thus, shouldn’t be accounted as LDs, even in a ‘weak sense’. Pre-LDs might sometimes precede lucidity, hence their name, but insofar as they don’t represent our current state as that of a dream (or a hallucination), and thus, don’t yield awareness of our current state as that of a dream, they aren’t lucid, not even in the weaker sense. Pre-LDs might involve a representation of some aspects of my experience as hallucinatory, thus leading me to have some feelings of unreality or oddness about my experience which might prompt me to question whether this is a dream without concluding that it is, as Green originally described ( 1968 ). Similarly, I might realise that my current phenomenal state has a particular distinctive feeling, like in the report of the dreamer describing seeing colours as they never have seen before (LaBerge & Rheingold, 1990 ). In this respect, one might have self-knowledge about their current state of awareness, as some research in non-LD metacognition shows (cf. Kahan 1994 ). Yet what matters and what distinguishes pre-lucidity from weaker lucidity is that in a lucid dreaming state my whole perceptual experience is represented as that of a state of dreaming, while in a pre-lucid one, only some elements are represented as hallucinatory. For a state to be lucid in the technical sense, the content of the state needs to be one in which the whole state is represented as a state that falls short of perception.

Such a technical account of lucidity can also explain the case of noetic feelings characterising what Windt and Metzinger describe as A-lucidity or weak lucidity. As introduced in §2.2, Windt ( 2015b ) suggests that for a state to be lucid, certain feelings of knowing, like the feeling of familiarity, shouldn’t be restricted to certain contents of my dream experience (i.e. recognising someone or something as familiar), but enable me to recognise that my experience is a dream (p.431). Here I take this suggestion made by Windt and argue that, in fact, it’s this recognition of the hallucinatory nature of my state which enables me to provide the right explanation for my feeling of familiarity; the fact that all this is a dream. Merely having self-knowledge about the phenomenal character of my experience, namely, realising about my feeling of familiarity, won’t do—the feeling of familiarity alone cannot be counted as an instance of lucidity, only as a case of pre-lucidity if it leads to the recognition of the hallucinatory character of my experience. For a noetic feeling to count as a case of minimal lucidity, such a feeling should be brought about in virtue of representing my current state as a state falling short of perception (in a conceptual or non-conceptual way).

3 The Technical Account in States Outside Dreaming

After having considered the technical notion of lucidity used in dream research, fleshed out the different ways in which it can be understood, and proposed a unified account, I show how this notion of lucidity can also be applied to other states outside dreaming. Since, after all, the question that I raised in this article is whether the sort of conscious sleep experiences described by Tibetan Buddhist traditions could be regarded as being lucid in this respect, we ought to see whether the technical account of lucidity can apply to other states other than dreaming.

Remember that the technical account of lucidity refers to states in which our current state is represented as one that lacks perceptual contact with the world, or a state that falls short of perception. Described in this more generalist way, without being specific about the case of dreaming, this definition applies to other conscious states, like instances of recognising simple visual hallucinations or illusions in non-pathological cases. Think of the first time you were told about a particular visual illusion (or try a new one by yourself). If we take the Hermann-Herring grid as an example, when looking at the grid we usually experience (more or less intensely) black dots appearing and disappearing at the intersection points. The onset of lucidity comes when we’re told that the black dots aren’t actually drawn in the picture, but that they’re afterimages. We have a sudden realisation that we were wrong—that which we were taking to be ‘seeing’ isn’t indeed a real percept but a hallucination; or, in this case, a form of illusion if you wish (see Macpherson & Batty 2016 ). In those cases, the episode of lucidity might be very brief but meets the same conditions for the technical account of lucidity outlined above: there’s a recognition in a conceptual or non-conceptual way of the hallucinatory character of our current experience. Footnote 13 We find more immersive examples in virtual reality (VR) environments. When wearing the head-mounted display, and especially if it’s our first time in VR or in a new environment, we feel fully immersed in the VR scenery. Footnote 14 Yet, while in VR, we (implicitly) know that we’re not indeed at a mountain’s peak or under the sea but that we’re in fact standing on our living room floor and that what we’re taking as being in front of us is a computer-generated image. In those cases of illusions, hallucinations and VR, what we’re lucid about is that we correctly characterise our perceptual experience as illusory or hallucinatory; we know that what we take to be perceiving doesn’t exist but is just simulated perception.

Thus far I’ve argued that the distinctive feature of lucidity is that of recognising the hallucinatory nature of our ongoing experience. Nonetheless, it should be noted that this is a strict way of interpreting this technical notion of lucidity; it only considers cases where I rightly recognise my current experience as one that falls short of perception. However, a more liberal reading of this notion can be taken to include cases in which I either realise that my past experience fell short of perception (which at that time taken wasn’t taken to be a hallucination), I correctly realise that I’m right now in a non-hallucinatory state—I’m in a state of perception— , or both. I suggest the case of ‘insightful psychosis’ to illustrate this alternate reading of the technical account. Sometimes, psychotic patients spontaneously, or after therapy, gain an understanding of the nature of their hallucinatory experiences; they acknowledge them as being hallucinations (Voss et al. 2018 ). A tentative suggestion is that what these patients realise is that their current experience is one of perception; that they’re indeed perceiving something and were previously mistaken. This suggestion would fit nicely with preliminary research pointing at similar mechanisms playing a role in the acquisition of lucidity between psychotic patients and LD (ibid). Furthermore, considering the shared phenomenological features between lucidity in psychotic patients and lucidity in LD, some researchers are promoting the potentiality of LD therapy to treat psychotic patients (Dresler et al. 2015 ). Given this possible connection between the sort of lucidity in dreaming and other pathological cases, it could be beneficial to take the technical notion of lucidity in a more liberal sense to include cases where lucidity is gained by virtue of recognising reality as reality and acknowledging that we had previously been in a hallucinatory or altered state of consciousness. This approach would not only facilitate the investigation of the phenomenal features of lucidity across different conscious states but would also shed light on the different degrees of lucidity one can have, and the different ways it can be expressed.

Moreover, a liberal reading of the technical notion of lucidity might also shed light on certain cases of LD where explaining lucidity in a strict sense might not work. For instance, consider cases of double awareness of one’s dreamt body and physical body described by some lucid dreamers. In one of his first descriptions of the term dream lucidity, Van Eeden ( 1913 ) describes a LD in which he could observe the sensations on the chest in his dreaming body and the sensations on his back in his physical body resting in the bed. Thus, there’s a way in which Van Eeden realises that his current experience has both hallucinatory and perceptual features (i.e. the dreamt body and the physical body). Similar cases are reported by lucid dreamers taking part in experimental research that uses light cues as an induction method for lucidity (Carr et al. 2020 ). In those cases, lucid dreamers realise about the external cues and recognise them as veridical (they realise them as veridical percepts), but at the same time, they realise that other features of their current mental state don’t amount to perceptual experience (and thus, that they are LD). By teasing out the technical notion of lucidity in the strict and liberal sense, we’re able to account for those cases in which one is strictly lucid about certain aspects of the experience and liberally lucid for others. Footnote 15

Finally, there’s another alternate reading of the technical notion of lucidity that can be made to account for other phenomena that share some phenomenological features of lucidity, yet they aren’t usually considered lucid states since they don’t yield justified true belief about our current state. This is the case of false awakenings (FAs); dreams involving a false belief that we have just awakened and that our previous experience was a dream. In the literature, FAs are taken as cases of non-lucidity (Buzzi 2011 )—after all, we don’t realise that we’re indeed dreaming. Nevertheless, FAs have some distinctive features that remind us of full-fledged forms of LD since they’re described as being an experience of “striking realism” (Green & McCreery 1994 ), as “real as wakefulness” (Buzzi 2011 :122). FAs are experienced in such a realistic way that some individuals, even after properly awakening, still take FAs to be instances of actual awakenings, or worry whether they have finally awakened at all (ibid, p.114). Moreover, FAs can occur several times in a row, and some report ‘waking up’ many times in a FA, every time being convinced of having finally woken up (ibid). By sticking to the technical account of lucidity, we can regard FAs as cases of false lucidity. Like lucid states read in the liberal sense, cases of false lucidity involve a representation of our state as that of perception. However, contrary to states of strict or liberal lucidity, false lucid states yield a false belief about the fact that I’m actually perceiving something.

Some of the benefits of regarding states like FAs as instances of false lucidity is that we could strengthen the link between the similar phenomenological features of such states and LDs (Buzzi 2011 ; Zink & Pietrowsky 2015 ). In this respect, we can piggyback the sort of experience had during FAs to that of pre-lucidity outlined in the previous section. During FAs, the dreamer wonders whether they’re dreaming, yet they erroneously conclude that they’re awake. Footnote 16 In a way then, these sorts of experiences provide the dreamer with self-awareness of their current state, yet they aren’t lucid in the technical sense insofar as they don’t yield awareness of the whole state as a hallucinatory state. Other altered states of consciousness also provide examples of false lucidity, such as mystical or religious experiences (James 1982 ; Stace 1961 ). Some mystics phenomenologically describe those states as revelatory experiences involving an “intellectual illumination” about having understood something new (see the report by Bucke, 1901 in James 1982 :385). Others regard their mystical experiences as being in direct contact with a deity or unreal entity (Forman 1990 ). For some mystics, mystical experiences are regarded as cases of perception, “states of insights into the depths of truth” (James 1982 :367). As with false awakenings, the mystic is convinced about knowing what the nature of their state is, yet they categorise it wrongly. Footnote 17 By broadening our understanding of lucidity to include cases of false lucidity we could examine more carefully the onset of lucidity and investigate whether there’s something special about having a true or false belief about the nature of our current state or whether this isn’t a required condition for experiencing lucidity in the technical sense.

4 Towards a Broader Account of Lucidity

4.1 lucid dreamless sleep and the clear light sleep.

Thus far, I’ve argued that what makes a state to be minimally lucid, in a technical sense and taking a strict reading of the notion, is the fact that our current state of awareness is represented as a state that falls short of perception or lacks perceptual contact with the world. I’ve examined how such a notion could be applied to other conscious states outside dreaming and the different readings that could be made of it to account for similar states. In this last section, I examine a recent proposal which characterises the phenomenon of the clear light sleep as a state of ‘lucidity’ similar to that had during LD. I apply the technical notion of lucidity and show the problems arising from understanding such a state as “lucid” in the technical sense. I then consider an alternative reading and how a more relaxed notion of lucidity could be applied to such a state.

The clear light sleep is an aspirational state of consciousness described by the Dzogchen lineage in Tibetan Buddhism. By following a series of proficient meditative practices, one is said to reach a state where one realises that all phenomena have an illusory nature and perceives reality as it is (Padmasambhava & Gyatrul 2008 ). Such practices can be followed while awake, but also during sleep, as detailed by the practice of ‘the bardo of sleep’ (Padmasambhava & Gyatrul 2008 ; Ponlop 2006 ). This practice aims to cultivate a sort of awareness that allows one to reach a state of “luminosity” or “clarity” (Fremantle 2001 ), a state where one recognises the “nature of the mind” (Dalai Lama, 1996 ; Ponlop 2006 :86)—one recognises the essence of the mind. Footnote 18 What’s more, according to Dzogchen, such a state is conceptualised as a state of pure awareness or “bare awareness” (Ponlop, 2006 :13; Wangyal 1998 ). It’s important to note that these descriptions of the clear light sleep rely on metaphysical claims about the mind by Tibetan Buddhism and not on phenomenological or first-person reports offered from such a state. Footnote 19 Moreover, it should also be noted that the aspirational state of clear light is heterogeneously described in the literature. It’s then a question for further research whether such descriptions are, in fact, talking about the same state, that of a state of pure awareness conceptualised by the Dzogchen tradition or are indeed talking about different states. I’ll come back to such a worry in the last subsection. For now, I’ll focus on examining the state of the clear light sleep characterised as a state of non-duality, a state that lacks the subject-other distinction of ordinary conscious states and that is taken by Tibetan Buddhist traditions to be an objectless state; it’s said to lack an object-directed awareness inasmuch as it lacks a distinctive object of awareness from the mind itself (cf. Alcaraz-Sánchez 2021 ; Alcaraz-Sánchez et al. 2022 ).

While certain descriptions of the clear light sleep allude to a state of lucidity or clarity in which one recognises the essence of the nature of consciousness, here it’s important to note that Tibetan Buddhist traditions don’t understand this state as involving any sort of second or higher-order awareness (i.e. a state that takes a distinct first-order state as its intentional object). Instead, many authors endorse a reflexive account of consciousness and defend that what makes a state conscious is an aspect of consciousness that refers to itself, or self-awareness—in short, every conscious state is conscious of itself (see MacKenzie 2007 ). Footnote 20 According to authors supporting this account, when we’re conscious, we’re pre-reflectively (or reflexively) self-aware of our current conscious state in virtue of being phenomenally conscious; the self-awareness is said to be given in the phenomenal character of the experience. Thus, these traditions support the existence of a state in which the only thing that remains is this self-awareness aspect of consciousness, that which is intrinsic and essential to consciousness.

Following this view on the reflexivity of consciousness portrayed by Buddhist traditions, the state of luminosity or clarity achieved during deep sleep should be attributed to the apprehension of the qualitative character of the experience—the what-is-it-likeness of the experience (Nagel 1974 ). Under this reading, a luminous state is a state of awareness of the subjective character of experience; what’s experienced is the quality of consciousness itself (Fasching 2008 ; Ram-Prasad 2007 ; Thompson 2014 ). It seems that the most natural way to understand such a state would then be to conceptualise it as a state of phenomenal consciousness —a state in which there’s something it is like to be in that state. However, Thompson ( 2015 ) has pointed out how this approach won’t do justice to the descriptions made by Buddhist traditions that consider access to the content of our phenomenal experience during the clear light sleep (p.11). Footnote 21 As such, he has attempted to explain this sort of awareness during the clear light sleep as a state of “non-conceptual meta-awareness” ( 2015 :1) and suggested a possible link with the state of LD, thus coining the term “lucid dreamless sleep” (Thompson 2014 ). Windt ( 2015a ) has also proposed that during the clear light sleep what remains is a “feeling of just having become aware of the nature of one’s ongoing state” (p.20) and pointed out its possible connections to LD. While the proposal by Thompson and Windt seems to be quite modest—that certain instances of the clear light sleep could be explained as a similar sort of awareness had during certain sorts of LD— their construct of “lucid dreamless sleep” and the adoption of it in recent literature is imprecise and unclear. Here, and in the following section, I examine the different ways to interpret it, and its different implications.

Given the suggestion by Thompson and Windt the state of lucid dreamless sleep could be related to that of lucid dreaming, the most intuitive way to understand this new construct is to interpret it by applying the notion of lucidity used in lucid dreaming research. That is, to apply the technical notion of lucidity. Note though that lucidity, in the technical sense, can be understood in a stronger or weaker sense. Thompson and Windt say is the latter what they’re considering, a state of “non-conceptual lucidity” or “weak lucidity”. I argued that we could grant a state of non-conceptual awareness to be lucid if it still involves the representation of my current state as one that falls short of perception (or as one of veridical perception, if we take a more liberal sense of the notion). While it’s a contentious point of debate whether such a state should be in fact a state of non-conceptual awareness, I noted that what’s important when conceiving states of weak lucidity (in technical terms) is to consider the content of such a state: that of representing the hallucinatory character of my state. We could then agree with Thompson and Windt and regard the state of “lucid dreamless sleep” as lucid in this weaker sense of the technical notion of lucidity. However, by applying the technical notion of lucidity to lucid dreamless sleep, we would then be describing a state that involves representing our current state as falling short of perception, even if we grant that such representation could be done in a non-conceptual manner, as Thompson and Windt defend.

Although this approach of applying the technical notion of lucidity to lucid dreamless sleep might seem the most straightforward one, given the suggested link between this state and the state of dream lucidity, such an approach would then raise the question as to whether the state of clear light sleep, as described by Tibetan Buddhist traditions, is the sort of state that can be regarded as lucid in this technical sense. If according to Tibetan Buddhist traditions the state of the clear light sleep is indeed a state of pure awareness, a state in which I’m not cognising or perceiving anything, it doesn’t seem to be the sort of state in which anything is represented as hallucinatory or not, or as falling short of perception, and thus, the technical notion of lucidity cannot be applied in this case. Similarly, from the descriptions provided by Thompson and Windt of the state of lucid dreamless sleep, it doesn’t seem either that this is the sort of notion of lucidity they have in mind, and thus, it calls into question the suggestion that the sort of lucidity during dreamless sleep should be akin to that had during lucid dreaming. Considering this, we have two alternatives. We can either cease using the technical notion of the term ‘lucidity’ to describe the clear light sleep, since it doesn’t seem to be the right sort of state to be lucid (either because there’s nothing to be represented as hallucinatory or because there’s nothing that can be represented at all) or abandon the technical account of lucidity and find a more relaxed one. For the remainder of the paper, I’ll focus on the latter and offer an account that aims at overcoming this problem.

4.2 The Broader Account of Lucidity

I propose a broader sense in which a state can be understood as lucid, drawing from the descriptions offered by the Tibetan Buddhist literature of the state of the clear light instead of the notion of lucidity used in LD research. According to those traditions, the aspirational state sought while engaging in clear light sleep practices is a state in which one realises the true nature of the mind. As I mentioned, such descriptions rely on metaphysical claims taken by Tibetan Buddhist traditions about the mind, namely, the fact that one encounters the essence of consciousness in such a state. Here, I leave aside how such a state should be considered in metaphysical terms, and instead, focus on how it might be like phenomenologically:

Broader lucidity: A state involving the seeming recognition that one is directly acquainted with one’s phenomenal character of one’s experience.

This broader account of lucidity is meant to be an alternative notion of lucidity that can be used to explain cases that cannot be covered or are difficult to explain using the technical account exposed earlier. For instance, in the case of dreaming, the broader account might prove to be useful to distinguish between pre-lucidity and minimal lucidity. In a pre-LD, I might have a feeling that I’m dreaming, yet not represent the hallucinatory character of my current state, and thus, not be lucid in the technical (and strict) sense. However, I can be said to be lucid in the broader sense, if such a state involves the feeling of seeming to be acquainted with the nature of my current state; to realise what makes my state distinctive and to be the sort of state it is (as accounted by Tibetan Buddhist traditions). By counting with these two notions of lucidity, we could make sense of limit cases that are difficult to discriminate as “weakly lucid” or “pre-lucid” as the example of realising that one is experiencing colours as one has never done before, as illustrated by Windt and Metzinger (see §2.1). Regarding the latter example, we could say that the dreamer wasn’t technically (minimally) lucid (since the state wasn’t one of representing the current experience as hallucinatory). Yet, we could say that the dreamer was lucid in a broader sense since they seemed to be in direct contact with the nature of their current state, namely, the distinctive phenomenal character of their experience. Footnote 22

Similarly, we can apply this broader notion of lucidity to some instances of the clear light sleep, or “lucid dreamless sleep” as referred to by some authors. Recall that such a state of clear light is conceived by Dzogchen teachings as a state of non-dual awareness, a state in which one is merely conscious of consciousness-as-such; one is said to be in a state of pure awareness. Nevertheless, according to traditional descriptions of the clear light sleep, such a state doesn’t involve any sort of object-directed or second-order awareness, but instead, it should be described as a state of pre-reflexive self-awareness. Thus, according to these traditional descriptions of the clear light sleep, such a state involves an awareness of the qualitative aspect of consciousness simpliciter; an awareness of the phenomenal character of the experience of ‘just awareness’. Thus, we could say that the clear light sleep might be broadly lucid if it involves the phenomenology of seeming to be in direct contact with the nature of one’s experience, the distinct phenomenal character of such a state.

I argue that such an account of broad lucidity can describe better what Thompson and Windt seem to have in mind when describing the state of lucid dreamless sleep. Moreover, such an account would fit in nicely with Windt’s recent proposal regarding the state of “lucid dreamless sleep” as a state of “phenomenal knowing” ( 2015a :20), a state involving “the feeling of just having become aware of the nature of one’s ongoing state” (ibid). For Windt and Thompson, the state of “lucid dreamless sleep” is a conscious state involving the noetic feeling of knowing that one is aware—our current conscious state is represented non-conceptually as a state of consciousness or phenomenal consciousness. They take this state to lack any sort of propositional thought, yet they still conceive it as involving certain intentional content, that of representing the state as a state of awareness (see Thompson 2015 ; Windt 2015a ). Footnote 23 While this state might appear as resemblant to the sort of lucidity experienced during LD, it’s a different one since it doesn’t represent our current state of awareness as being a state that lacks perceptual contact with the world. Instead, such a state might be represented as a state that otherwise lacks content (a state of just awareness), or if we take the metaphysical claim of Tibetan Buddhism at face value, might be a state in which nothing is represented at all. Footnote 24

4.3 Imageless Lucid Dreaming and Experiences of the Void

In the previous sub-section, I have shown how the state of the clear light, as understood by certain Tibetan Buddhist lineages like Dzogchen, shouldn’t be regarded as a state of lucidity in the technical sense of the word since this would instead portray a conscious state involving a representation of the hallucinatory character of my current state. In order words, such a state would involve representing my current state as one that falls short of perception. As I showed throughout §2, this account of lucidity considers the technical definition of lucidity in LD research and points out what is distinctive of this state. However, if we want to be faithful to the Tibetan Buddhist descriptions of the clear light sleep, it seems that such a state cannot be characterised as ‘lucid’ in that technical sense. The sort of state at stake seems to be one that merely involves the representation of a state of ‘pure awareness’, a state that otherwise lacks content, or if we’re strict about the meaning of ‘pure awareness’, we’re then conceiving a state that doesn’t represent anything at all. Either way, it seems that the technical notion of lucidity cannot be applied in this case, and thus, the construct of “lucid dreamless sleep” should either be dropped or clearly used in reference to the broader sense of lucidity I presented in §4.2. Notwithstanding this alternate approach, one could argue that there’s still a way in which the state of the clear light could be understood as lucid in the technical sense. In this last sub-section, I consider this possibility and its implications.

As previously mentioned, the state of clear light is heterogeneously described in different Tibetan Buddhist texts and their translations which might lead us to question to what extent those descriptions are indeed talking about the same phenomenon. An example of it are the descriptions of the attainment of clear light via the dissolution of the dream environment mentioned in practices of “dream yoga” or “yoga nidra” (Holecek, 2016 ; Norbu 1983 ; Saraswati 1984 ; Wallace 2012 ). The teaching of those practices describes the achievement of the state of clear light by actively making the dream environment disappear while in a LD (Chang 1963 ; Evans-Wentz 1960 ; Wallace 2012 ). Other teachings also mention the possibility of reaching the clear light while falling asleep and remaining on the threshold of dreaming (Wangyal 1998 ). Footnote 25 If taken at face value, those descriptions would be pointing at a state of clear light, a state of pure awareness achieved after the dissolution of the dream or before the appearance of the dream. Anecdotal phenomenological descriptions of this state can be found in the Tibetan Buddhist literature but also amongst LD practitioners, usually under the name of ‘void’ experiences or ‘clear light dreams’ (Johnson 2020 ; Magallón, 1987 ).

Here I claim that such states of ‘void’ or ‘clear light dreams’ could be understood as per the technical notion of lucidity if such states are regarded as perceptual states; states in which I’m aware that I’m in a state that lacks a dream environment. This claim would be supported by recent phenomenological reports of those experiences collected by empirical work (see Alcaraz-Sánchez 2021 ; Alcaraz-Sánchez et al. 2022 ). Those reports point to an experience that in some cases seems to involve a certain ‘distinct’ object of awareness, like the awareness of one’s location in the ‘void’ or one’s self-experience in such a state (ibid). These reports also seem to match with previous descriptions of the experience of the ‘void’ in the LD literature which describe such states as involving a minimal sense of self-other distinction like a very minimal perception of spatiotemporality (see Johnson 2020 ). This is the case of what is usually referred to as “imageless lucid dreams” or “minimal perceptual environments” (Gillespie 2002 ; LaBerge & DeGracia 2000a , b ; Magallón, 1987 ), sleep experiences that lack imaginative or visual experience yet they still involve some sort of perceptual experience. By understanding those experiences as perceptual, we could regard them as lucid in the technical sense and say that one was lucid in the void insofar as one was aware of the hallucinatory character of their experience (or one was aware that their experience was one of perception if we consider a liberal reading as outlined in §2.3). However, the consequence of regarding such states as involving a minimal sort of perceptual experience is that such states would then be conceived as a sort of dream, and thus, not as a sort of dream- less sleep experience (as described by Windt et al. 2016 ). Some authors have suggested that these experiences of the ‘void’ or ‘clear light dreams’ could indeed be understood as minimal forms of dreaming insofar as they involve a minimal sense of immersion and self-other distinction (Windt 2015a :16), as well as a minimal sense of spatial location (see Alcaraz-Sánchez 2021 :21–22). Therefore, we would need to conduct further research to conclude whether the experience of clear light, as described by Tibetan Buddhist traditions, refers indeed to a minimal sort of dreaming. Note that the use of the technical notion of lucidity to describe those states of the void could only be considered if we conclude that such states are a sort of minimal dreaming, and thus, perceptual experiences. If, on the contrary, we conclude that such states aren’t a type of minimal dreaming, or are indeed dreamless sleep experiences, we could only consider them as ‘lucid’ as per the broader notion introduced in §4.2, states in which I know about the nature of my current conscious state in virtue of seeming to be in direct contact with the phenomenal character of my experience.

5 Conclusion

This paper examined the suggestion made by some authors (see Thompson 2014 ; 2015 ; Windt 2015a ; Windt et al. 2016 ) that the state of the clear light sleep, as described by Tibetan Buddhist traditions, could be understood as ‘lucid’ in a similar sense to the state of lucid dreaming. To that aim, I put forward a unified technical account of lucidity aiming at capturing what makes a state minimally lucid. I propose that a minimally lucid state is that which represents our current state as a state that falls short of perception—it represents the hallucinatory nature of our state. I showed the motivation for such a technical account by applying it to other states outside dreaming, and by teasing apart the different readings that can be made of it ( stricter, liberal and false lucidity , as well as stronger and weaker lucidity). I argued that none of these readings can be applied to the state of the clear light sleep since this isn’t the right sort of state that can be represented as lacking perception, and thus, a more relaxed notion of lucidity is needed. I finished by suggesting the notion of broader lucidity , which regards lucidity as the seeming realisation that one is in direct contact with the phenomenal character of the experience. I argued that, in this broader sense, we could take the clear light sleep as lucid if it’s conceived as a state involving the representation of my current state as that of just awareness. Moreover, I also examined how the so-called state of the clear light could be regarded as lucid in the technical sense if it’s instead regarded as a state of dreaming, and thus, a perceptual state. Overall, I provided a more fine-grained analysis of the construct of “lucid dreamless sleep” than that found in the literature, and the many ways in which the state of clear light sleep, as described by Tibetan Buddhist traditions, can be conceived. Further empirical and conceptual work is required for understanding better the different ways in which lucidity during dreamless sleep can be instantiated and how such states could be linked to other sorts of sleep phenomena, such as dreaming, lucid dreaming or even other forms of sleep consciousness.

Note that several Tibetan Buddhist traditions assert that all conscious experiences involve a self-awareness aspect; according to those traditions, conscious states involve a form of pre-reflective self-awareness, which is referred to as the “self-awareness” or “self-luminosity” aspect of consciousness (see McKenzie, 2007 for a discussion). According to these traditions, self-awareness is a non-dual state that lacks the subject/object structure of ordinary awareness (see Kellner 2010 ; Williams 1998 ). I will comment this further in §4.1.

LaBerge developed a pioneering experimental method to assess dream lucidity in real time consisting in asking participants to carry out a distinctive pattern of eye movements when dreaming and realising they are dreaming. Those distinctive eye patterns can be observed on the EEG and allow researchers to conduct empirical validations of dream lucidity (LaBerge 1980 , 1985 ; LaBerge et al. 1981 ). Recently, such eye-signalling method has also allowed researchers to carry out a two-way communication channel in which the researcher ‘communicates’ with the lucid dreamer in-real time (see Konkoly et al. 2020 ).

Windt and Voss ( 2018 ) point out how lucidity lapses aren’t exclusive from LD, but that they also appear in contexts enhancing the feeling of presence—feeling of being there—, such as virtual reality settings and threating situations (p.400) According to these authors, lucidity can then co-exist with naïve-realistic beliefs about our experience (see also Windt 2015b :436).

Some research points towards the fact that the onset of lucidity might be experienced as having a particular phenomenal character (Barrett 1992 ; Mallett et al. 2021 ), however, there’s not enough data to conclude that dream lucidity is always experienced as involving a phenomenal shift, and that this is a necessary condition for LD.

Similarly, such an approach might also deem as LD certain dreams that might not involve lucidity in the technical sense of the word. For instance, some classic LD reports highlight the fact that the dreamer might be able to carry out the desired dream task, yet still deeming the dream environment as reality (see Worsley 1984 ). Moreover, some research has pointed out to the fact that the pre-established eye-signal might sometimes not even be carried out during sleep but during REM to wakefulness transition (see Mota-Rolim 2020 for a discussion).

Windt has related the sort of awareness occurring during A-lucid or weakly lucid dreams to the notion of “non propositional” or “procedural” metacognition (Proüst, 2007 , 2014 ). According to a growing number of theorists, metacognition doesn’t always require re-representation of our mental states, and thus, it shouldn’t be exclusively understood in terms of second-order state (or reflective awareness). Theorists holding such a framework argue that subpersonal processes can also monitor cognition (Beran et al. 2012 ) and thus, we can explain metacognition without appealing to propositional knowledge. Proponents of the existence of procedural metacognition argue that we can know something in virtue of knowing-how or having procedural knowledge (Fridland 2015 :713). While is a contentious topic of debate whether procedural metacognition should be regarded as ‘meta’-cognition, here I remain neutral about whether this should be regarded as a form of ‘meta’- cognition.

Similarly, Noreika et al. ( 2010 ) also talk of “lucidity types” (p.41) when coining what they consider as “pre-lucid” or a “weaker” sort of lucidity, like Attentional, Behavioural and Emotional lucidity types ( A , B and E-lucidity respectively). Nevertheless, they assert that only C or Cognitive lucidity should be considered as actually lucid (ibid).

This way of understanding ‘insight’ and thus, LD, is also portrayed by some authors under the notion of ‘pre-reflective self-awareness’. For instance, Windt claims that certain forms of lucidity don’t involve “conceptual mediated insight” and instead should be understood as forms of pre-reflective awareness (2015:26). Other authors also refer to it as a form of “non-propositional meta-awareness” (see Dunne et al. 2019 ) described as the experience of a certain phenomenal feeling during a dream. These authors use a notion of pre-reflectiveness similar to that used by the phenomenological tradition, understood as the self-awareness given in the experience (see Zahavi 2005 ).

Note that here I stick to the use of the term ‘perception’ as a successful term—a state in which my phenomenal experience matches the experience of a worldly object (a ‘real’ object) under the right conditions. My experience is a veridical one.

Here I follow a simulational account of dreaming which takes dreams to be simulational experiences of a self in a hallucinated world (cf. Revonsuo 2006 ; Windt 2010 , 2015b ). It should be noted that other rival views about the ontology of dreaming exist, such as the imagination theory of dreams (Ichikawa 2008 , 2009 ) or the pluralist account (Rosen 2018 ). For the purposes of this paper, I’m focusing on taking an account of dreaming that considers its phenomenal character, in particular, the phenomenological profile of LDs as recognised hallucinations (or pseudo-hallucinations if you wish). In any case, rival views on the ontology of dreams as imaginative experiences shouldn’t pose a problem on the technical account of lucidity outlined here; if dreams are conceived as imaginative experiences, LDs, under that view, would still involve a state in which I represent my current experience as not consisting of perceptual contact with the world.

Note that Windt and Metzinger ( 2007 ) go a step further and argue that the perfect recognition of the virtual character of one’s own experience can only be achieved during LD. According to these authors, perfectly fully-fledged lucid dreams allow the dreamer to recognise the fact that one’s experience is a hallucination or a virtually generated world which might trigger a sense of depersonalisation caused by the fact of realising that everything, including oneself, is a hallucination (p.224). However, when asserting this, these authors have in mind the experience of full-lucidity, not minimal lucid states. Following their view, full-fledged lucidity involves a phenomenal shift in our experience such as the experience of my conscious state as a simulation. As such, their view doesn’t allow for the possibility of what Metzinger coins “lucid waking”, the experience of full-fledged lucidity during waking states (cf. Metzinger 2003 :542). As per their view, full-fledged lucidity could only be had during psychiatric conditions or mystical experiences (ibid). Note again that here I only address what a minimally lucid state, on the bottom end of the lucidity spectrum, would be like.

Note that here I stick to a reading of ‘non-conceptual’ endorsed by many theorists who take graded views of lucidity as referring to mental states that represent the world in a certain way yet don’t require the bearer of those states to possess the concepts that specify the contents of such state (Bermúdez 1995 ). Thus, nonconceptual content is usually understood as a sort of content that eludes linguistic expression and that explains the existence of tacit knowledge, like that involved in grammar or skill learning (Cussins 1992 ), but also to explain the sort of representational content involved in perception (Bermúdez 1995 ; Peacocke 2001 ).While some authors do account for the existence of non-conceptual content as a sort of low-level of subpersonal information processing in which some aspect of another representation or a representational property is represented (see Bermúdez 2001 , 2007 ; Proüst, 2007 ; Shea 2014 ) it’s a contentious point of debate in analytic philosophy whether non-conceptual content exists at all, or whether such content should be considered as representational (see Toribio 2007 for a discussion).

Note that this definition of lucidity would somehow depart from some graded views asserting that lucidity, explained as the (conceptual) realisation of the hallucinatory character of our experience can only be had during dreams and other altered states of consciousness but not during wakefulness. For instance, according to Windt and Metzinger ( 2007 ), full-blown lucidity, understood as the realisation that I’m currently in a state of no perception, can’t be brought about during wakefulness—I can’t fully realise that my wakeful experience is a simulation created by my brain, and thus, regard my current perceptual state as simulation. Thus, these authors reject the idea of a state of “lucid waking” (p.212). Nonetheless, such a claim involves a strong view of what lucidity is and only considers the top extreme of the lucidity spectrum as conceived by classic views: a state of reflective and conceptual thought that might involve a phenomenal shift in our experience.

In the literature of VR this illusory perceptual experience is known as the ‘place illusion’— the experience of the VR environment as real, including a sense of immersion or ‘being there’ in the VR environment, even though we know that the environment is a simulation (Slater 2009 ). VR experiences can be very realistic and even have similar emotional effects as real ones (Slater & Sanchez-Vives, 2016 ).

Thanks to an anonymous reviewer for raising this point.

Sparrow et al. ( 2018 ) also take instances of FAs as cases of pre-lucidity.

A similar case can be found in out-of-body experiences (OBEs). During those, the individual experience themselves as having left one’s own body, usually in a crystal-clear manner (see Metzinger 2009 : 133). Some have suggested that OBEs might be a case of misinterpreted dreams—we dream that we’re leaving our bodies (see Windt 2015b : 485). While further research about the ontology of OBEs during sleep is needed, a wide body of research has previously highlighted the link between the sort of lucidity had during OBEs and LDs (Blackmore 1988 ; Green 1968 ; Levitan & Zimbardo 1999 ).

Descriptions of such practices are detailed in the Bardo Thödol, widely known as the Tibetan Book of the Dead, which is a compilation of the 8 th Century originals “Liberation Through Hearing During the Intermediate State” and “The Profound Dharma of the Natural Liberation through Contemplating the Peaceful and Wrathful” by Tibetan Buddhist master Padmasambhava.

Thanks to an anonymous reviewer for pointing out this. Note that according to Tibetan Buddhist doctrines, we live in a state of ignorance about reality since what we usually perceive are mere appearances and we don’t apprehend reality as it is, such as the perception of a ‘self’ who perceives ‘something’ (see Fremantle 2001 for a discussion).

It’s worth noting how this view is reminiscent of other more contemporary philosophical traditions, such as the phenomenological tradition in Western philosophy. Proponents of this tradition hold that consciousness is characterised by an essential aspect that is for-itself (Sartre 1956 ). See Kriegel ( 2003 , 2004 ), Kriegel & Zahavi ( 2015 ) and Zahavi ( 2005 ) for contemporary accounts supporting this view.

It’s beyond the scope of this article to offer an exhaustive analysis about the ontology of the clear light sleep as per Buddhist traditions, and how we should indeed be interpreting those descriptions. However, for the purposes here of examining how such a state could be taken to be a state of lucidity (in the technical sense) I will stick to Thompson’s account. Further research should spell out more carefully the different readings that can be made of the descriptions of clear light found in the literature and its metaphysical consequences.

Notwithstanding the benefits of the broader account, it should be stressed that such an account can’t accommodate certain states of lucidity, for which we would still want to keep the technical notion, such as cases of full-fledged lucidity.

One might take this to be a state in which one knows (non-conceptually) that one is dreamlessly sleeping; that is, the nature of one’s state is that of being in a state of dreamless sleep. However, if we want to be faithful to the descriptions of the clear light sleep made by the Dzogchen tradition as a state in which one is merely aware of the phenomenal character of such a state; a state in which there’s only awareness of the pre-reflective character of consciousness.

Note that further research should investigate whether a state of pure awareness is in fact a state that lacks content altogether, including representational content, or whether it still involves some representational content. For a further detailed discussion, see Metzinger ( 2020 )

Padmasambhava presents a technique for reaching this state through the dream state (see Padmasambhava & Gyatrul, Chapter 4).

Alcaraz-Sánchez, A. 2021. Awareness in the void: A micro-phenomenological exploration of conscious dreamless sleep. Phenomenology and the Cognitive Sciences . https://doi.org/10.1007/s11097-021-09743-0 .

Article   Google Scholar  

Alcaraz-Sánchez, A., Demšar, E., Campillo-Ferrer, T., & Torres-Platas, S. G. 2022. Nothingness Is All There Is: An Exploration of Objectless Awareness During Sleep. Frontiers in Psychology , 13 (June). https://doi.org/10.3389/fpsyg.2022.901031

Baird, B., S.A. Mota-Rolim, and M. Dresler. 2019. The cognitive neuroscience of lucid dreaming. Neuroscience and Biobehavioral Reviews 100 (March): 305–323. https://doi.org/10.1016/j.neubiorev.2019.03.008 .

Barrett, D. 1992. Just how lucid are lucid dreams? Dreaming 2 (4): 221–228. https://doi.org/10.1037/h0094362 .

Beran, M. J., Brandl, J. L., Perner, J., & Proust, J. 2012. On the nature, evolution, development, and epistemology of metacognition: introductory thoughts. In Michael J. Beran Johannes L. Brandl Josef Perner Joëlle Proust (Ed.), Foundations of metacognition (pp. 583–605). Oxford: Oxford University Press (OUP).

Bermúdez, J.L. 1995. Nonconceptual Content: From Perceptual Experience to Subpersonal Computational States. Mind & Language 10 (4): 333–369. https://doi.org/10.1111/j.1468-0017.1995.tb00019.x\ .

Bermúdez, J.L. 2001. Nonconceptual self-consciousness and cognitive science. Synthese 129 (1): 129–149. https://doi.org/10.1023/A:1012603425585 .

Bermúdez, J.L. 2007. What is at stake in the debate on nonconceptual content? Philosophical Perspectives 21 (1): 55–72. https://doi.org/10.1111/j.1520-8583.2007.00120.x .

Blackmore, S. 1988. A theory of lucid dreams and OBEs. In Conscious Mind, Sleeping Brain , ed. J. Gackenbach and S. LaBerge, 373–387. New York: Plenum.

Chapter   Google Scholar  

Bosinelli, M. 1995. Mind and Consciousness during sleep. Behavioural Brain Research 69: 195–201.

Brooks, J.E, & Vogelsong, J. A. 1999. The conscious exploration of dreaming: Discovering how we create and control our dreams. Bloomington, IN: First Books Library.

Buzzi, G. 2011. False awakenings in light of the dream protoconsciousness theory: A study in lucid dreamers. International Journal of Dream Research 4 (2): 110–116. https://doi.org/10.11588/ijodr.2011.2.9085 .

Carr, M., A. Haar, J. Amores, P. Lopes, G. Bernal, T. Vega, O. Rosello, A. Jain, and P. Maes. 2020. Dream engineering: Simulating worlds through sensory stimulation. Consciousness and Cognition 83 (January): 102955. https://doi.org/10.1016/j.concog.2020.102955 .

Chang, G. 1963. Teachings of Tibetan yoga . Secaucus: Citadel Press.

Google Scholar  

Cicogna, P.C., and M. Bosinelli. 2001. Consciousness during dreams. Consciousness and Cognition 10 (1): 26–41. https://doi.org/10.1006/ccog.2000.0471 .

Cussins, A. 1992. Content, embodiment and objectivity: The theory of cognitive trails. Mind 101 (404): 651–688. https://doi.org/10.1093/mind/101.404.651 .

Dalai Lama. 1996. Sleeping, Dreaming, and Dying: An exploration of Consciousness with the Dalai Lama . Boston: Wisdom Publications.

Dokic, J. 2012. Seeds of self-knowledge: noetic feelings and metacognition. In Michael J. Beran Johannes L. Brandl Josef Perner Joëlle Proust (Ed.) Foundations of metacognition (pp. 583–605). Oxford: Oxford University Press (OUP).

Dresler, M., R. Wehrle, V.I. Spoormaker, A. Steiger, F. Holsboer, M. Czisch, and J.A. Hobson. 2015. Neural correlates of insight in dreaming and psychosis. Sleep Medicine Reviews 20: 92–99. https://doi.org/10.1016/j.smrv.2014.06.004 .

Dresler, M., Eibl, L., Fischer, C. F. J., Wehrle, R., Spoormaker, V. I., Steiger, A., Czisch, M., & Pawlowski, M. 2014. Volitional components of consciousness vary across wakefulness, dreaming, and lucid dreaming. Frontiers in Psychology , 4 . https://doi.org/10.3389/fpsyg.2013.00987

Dunne, J.D., E. Thompson, and J.W. Schooler. 2019. Mindful meta-awareness: Sustained and non-propositional. Current Opinion in Psychology 28: 307–311. https://doi.org/10.1016/j.copsyc.2019.07.003 .

Evans-Wentz, W.Y. 1960. The Tibetan book of the dead . London: Oxford University Press.

Fasching, W. 2008. Consciousness, self-consciousness, and meditation. Phenomenology and the Cognitive Sciences 7 (4): 463–483. https://doi.org/10.1007/s11097-008-9090-6 .

Filevich, E., M. Dresler, T.R. Brick, and S. Kuhn. 2015. Metacognitive Mechanisms Underlying Lucid Dreaming. Journal of Neuroscience 35 (3): 1082–1088. https://doi.org/10.1523/JNEUROSCI.3342-14.2015 .

Forman, R. K. C. (Ed). 1990. The problem of pure consciousness. Mysticism and philosophy. New York: Oxford University Pres.

Fremantle, F. 2001. Luminous emptiness. Understanding the Tibetan Book of the Dead . Boston: Shambhala.

Fridland, E. 2015. Knowing-how: Problems and Considerations. European Journal of Philosophy 23 (3): 703–727. https://doi.org/10.1111/ejop.12000 .

Gackenbach, J., & LaBerge, S. (Eds). 1988. Conscious Mind Brain, Sleeping Brain . New York: Plenum Press.

Gillespie, G. 1983. Lucid Dreaming and Mysticism: A Personal Observation. Lucidity Letter 2 (3): 64.

Gillespie, G. 2002. Dreams and dreamless sleep. Dreaming 12 (4): 199–207. https://doi.org/10.1023/A:1021104527848 .

Green, C., & McCreery, C. 1994. Lucid Dreaming: The Paradox of Consciousness During Sleep . London: Routledge.

Green, C. 1968. Lucid dreams . London: Hamish Hamilton.

Holecek, A. 2016. Dream Yoga: Illuminating your life through lucid dreaming and the Tibetan yogas of sleep . Boulder, Colorado: Sounds true.

Horton, C.L. 2020. Key Concepts in Dream Research: Cognition and Consciousness Are Inherently Linked, but Do No Not Control “Control”! Frontiers in Human Neuroscience 14 (July): 1–4. https://doi.org/10.3389/fnhum.2020.00259 .

Ichikawa, J. 2008. Scepticism and the imagination model of dreaming. Philosophical Quarterly 58 (232): 519–527. https://doi.org/10.1111/j.1467-9213.2007.546.x .

Ichikawa, J. 2009. Dreaming and imagination. Mind and Language 24 (1): 103–121. https://doi.org/10.1111/j.1468-0017.2008.01355.x .

James, W. 1982. The Varieties of Religious Experience. A Study in Human Nature. Being the Gifford Lectures on Natural Religion . Fount Paperbacks.

Johnson, C. 2020. Complete book of Lucid Dreaming. A comprehensive Guide to Promote Creativity, Overcome Sleep Disturbances and Enhance Health and Wellness . Minnesota: Llewellyn.

Kahan, T.L. 1994. Measuring dream self-reflectiveness: A comparison of two approaches. Dreaming 4 (3): 177–193. https://doi.org/10.1037/h0094411 .

Kahan, T.L., and S.P. LaBerge. 1996. Cognition and metacognition in dreaming and waking: Comparisons of first and third-person ratings. Dreaming 6 (4): 235–249. https://doi.org/10.1037/h0094459 .

Kahan, T.L., and S.P. LaBerge. 2011. Dreaming and waking: Similarities and differences revisited. Consciousness and Cognition 20: 494–514. https://doi.org/10.1016/j.concog.2010.09.002 .

Kahan, T. L., LaBerge, S. P., Levitan, Lynnen., & Zimbardo, P. 1997. Similarities and Differences between Dreaming and Cogntion: An exploraory study. Consciousness and Cognition , 132–147. https://doi.org/10.1006/ccog.1996.0274

Kellner, B. 2010. Self-Awareness (svasamvedana) in Dignāga’s Pramānasamuccaya and vrtti: A Close Reading. Journal of Indian Philosophy 38 (3): 203–231. https://doi.org/10.1007/s10781-010-9091-y .

Konkoly, K., Appel, K., Chabani, E., Mironov, A. Y., Mangiaruga, A., Gott, J., Mallett, R., Caughran, B., Witkowski, S., Whitmore, N., Berent, J., Weber, F., Pipa, G., Türker, B., Maranci, J.-B., Sinin, A., Dorokhov, V., Arnulf, I., Oudiette, D., … Paller, K. (2021). Real-Time Dialogue between Experimenters and Dreamers During REM Sleep. Current Biology, 31, 1–11. https://doi.org/10.1016/j.cub.2021.01.026

Koriat, A. 2000. The Feeling of Knowing: Some Metatheoretical Implications for Consciousness and Control. Consciousness and Cognition 9 (2): 149–171. https://doi.org/10.1006/ccog.2000.0433 .

Kozmová, M., and R.N. Wolman. 2006. Self-awareness in dreaming. Dreaming 16 (3): 196–214. https://doi.org/10.1037/1053-0797.16.3.196 .

Kriegel, U. 2003. Consciousness as Intransitive Self-Consciousness: Two views and an Argument. Canadian Journal of Philosophy 33 (1): 103–132. https://doi.org/10.1080/00455091.2003.10716537 .

Kriegel, U. 2004. Consciousness and Self-Consciousness. The Monist 87 (2): 182–205. https://doi.org/10.2307/2178689 .

Kriegel, U., & Zahavi, D. 2015. For-me-ness: What it is and what it is not. In and W. H. D. O. Dahlstrom, A. Elpidorou (Ed.), Philosophy of Mind and Phenomenology: Conceptual and Empirical Approaches (pp. 36–53). New York: Routledge.

Kühle, L. 2015. Insight : What Is It, Exactly ? Open Mind. 38(C) https://doi.org/10.15502/9783958570696

LaBerge, S.P. 1980. Lucid Dreaming as a Learnable Skill: A Case Study. Perceptual and Motor Skills 51: 1039–1042. https://doi.org/10.2466/pms.1980.51.3f.1039 .

LaBerge, S., and H. Rheingold. 1990. Exploring the world of lucid dreaming . New York: Ballantine Books.

LaBerge, S.P., L.E. Nagel, W.C. Dement, and V.P. Zarcone. 1981. Lucid dreaming verified. Perceptual and Motor Skills 52: 727–732.

LaBerge, S. P., & DeGracia, D. J. 2000. Varieties of Lucid Dreaming Experience. In R. G. Kunzendorf & B. Wallace (Eds.), Individual differences in conscious experience (pp. 269–307). Amsterdam: John Benjamins. https://doi.org/10.1075/aicr.20.14lab

LaBerge, S. P. 1985. Lucid Dreaming: The Power of Being Awake and Aware in Your Dreams . New York: Ballantine.

Levitan, L., and P. Zimbardo. 1999. Out-of-body experiences, dreams, and REM sleep. Sleep and Hypnosis 1 (3): 186–196.

MacKenzie, M. D. 2007. The Illumination of Consciousness: Approaches to Self-Awareness in the Indian and Western Traditions. In Philosophy East and West (Vol. 57, Issue 1, pp. 40–62). https://doi.org/10.1353/pew.2007.0006

Macpherson, F., and C. Batty. 2016. Redefining Illusion and Hallucination in Light of New Cases. Nous-Supplement: Philosophical Issues 26 (1): 263–296. https://doi.org/10.1111/phis.12086 .

Magallón, L.L. 1987. Awake in the Dark : Imageless Lucid Dreaming. Lucidity Letter 6 (1): 1–5.

Mallett, R., M. Carr, M. Freegard, K. Konkoly, C. Bradshaw, and M. Schredl. 2021. Exploring the range of reported dream lucidity. Philosophy and the Mind Sciences 2 (1): 1–23. https://doi.org/10.31219/osf.io/sz8fa .

Metzinger, T. 2009. The Ego Tunnel . New York: Basic Books.

Metzinger, T. 2020. Minimal phenomenal experience. Philosophy and the Mind Sciences 1 (I): 1–44. https://doi.org/10.33735/phimisci.2020.I.46 .

Metzinger, T. 2003. Being no one. In Metzinger, T. (2003). Being No One. The Self-Model Theory of Subjectivity. MIT Press, Cambridge, MA (MIT Press). https://doi.org/10.1017/CBO9781107415324.004

Moss, K. 1986. Phenomenology: Personal and Theoretical Considerations The Dream Lucidity Continuum. Lucidity Letter 5 (2): 2–4.

Mota-Rolim, S.A. 2020. On Moving the Eyes to Flag Lucid Dreaming. Frontiers in Neuroscience 14 (April): 1–5. https://doi.org/10.3389/fnins.2020.00361 .

Nagel, T. 1974. What Is It Like to Be a Bat? The Philosophical Review 83 (4): 435. https://doi.org/10.2307/2183914 .

Nikhilananda, S. 1949. Mandukya Upanishad with Gaudapada’s Karika and Sankara’s Commentary (3rd ed.). Bangalore: Bangalore Press.

Norbu, N. 1983. Dream yoga and the practice of natural light (M. Katz, Ed.). Ithaca, New York: Snow Lion Publications.

Noreika, V., J.M. Windt, and B. Lenggenhager. 2010. New perspectives for the study of lucid dreaming : From brain stimulation to philosophical theories of self-consciousness. International Journal of Dream Research 3 (1): 36–45. https://doi.org/10.11588/ijodr.2010.1.586 .

Olivelle, P. (Trans.). 1998. The early Upanishads: Annotated text and translation. New York; Oxford: Oxford University Press.

Padmasambhava, Gyatrul, R. 2008. Natural Liberation. Padmasambhava’s Teachings on the Six Bardos (A. Wallace, Trans.) . Ithaca, New York: Wisdom Publications (original work 1998).

Peacocke, C. 2001. Does Perception Have a Nonconceptual Content? Journal of Philosophy 98 (5): 239–264. https://doi.org/10.2307/2678383 .

Ponlop, D. 2006. Mind Beyond Death . Ithaca, New York: Snow Lion Publications.

Proüst, J. 2007. Metacognition and metarepresentation: Is a self-directed theory of mind a precondition for metacognition? Synthese 159 (2): 271–295. https://doi.org/10.1007/s11229-007-9208-3 .

Proüst, J. 2014. A Representational Format for Procedural Metacognition. In The Philosophy of Metacognition: Mental Agency and Self-Awareness (pp. 583–605). Oxford: Oxford University Press (OUP).

Ram-Prasad, C. 2007. Indian Philosophy and the consequences of knowledge: Themes in Ethics, Metaphysics and Soteriology . Aldershot: Ashgate.

Raveh, D. 2008. Ayam aham asmīti: Self-consciousness and identity in the eighth chapter of the Chāndogya Upanişad vs. Śankara’s Bhāşya. Journal of Indian Philosophy 36(2): 319–333). https://doi.org/10.1007/s10781-007-9031-7

Revonsuo, A. 2006. Inner presence: Consciousness as a biological phenomenon . Cambridge, MA: MIT Press.

Rinpoche, G. 2002. Meditation, transformation and dream yoga (Wallace, A., & Khandro, S.,Trans) (2nd ed.). New York: Snow Lion Publications.

Rosen, M.G. 2018. How bizarre? A pluralist approach to dream content. Consciousness and Cognition 62 (August 2017): 148–162. https://doi.org/10.1016/j.concog.2018.03.009 .

Saraswati, S.S. 1984. Yoga Nidra . Muger, Bihar: Yoga Publications Trust.

Sartre, J. P. 1956. Being and Nothingness (Barnes, H. Trans.) . New York: Philosophical Library.

Shea, N. 2014. Reward Prediction Error Signals are Meta-Representational. Noûs 48 (2): 314–341. https://doi.org/10.1111/j.1468-0068.2012.00863.x .

Slater, M. 2009. Place illusion and plausibility can lead to realistic behaviour in immersive virtual environments. Philosophical Transactions of the Royal Society b: Biological Sciences 364 (1535): 3549–3557. https://doi.org/10.1098/rstb.2009.0138 .

Slater, M., and M.V. Sanchez-Vives. 2016. Enhancing our lives with immersive virtual reality. Frontiers Robotics AI 3 (DEC): 1–47. https://doi.org/10.3389/frobt.2016.00074 .

Sparrow, G.S., M. Thurston, and R. Carlson. 2013. Dream reliving and meditation as a way to enhance reflectiveness and constructive engagement in dreams. International Journal of Dream Research 6 (2): 14–23. https://doi.org/10.11588/ijodr.2013.2.10151 .

Sparrow, G., R. Hurd, R. Carlson, and A. Molina. 2018. Exploring the effects of galantamine paired with meditation and dream reliving on recalled dreams: Toward an integrated protocol for lucid dream induction and nightmare resolution. Consciousness and Cognition 63 (June): 74–88. https://doi.org/10.1016/j.concog.2018.05.012 .

Stace, W.T. 1961. Mysticism and Philosophy . London: Macmillian.

Stumbrys, T., D. Erlacher, M. Johnson, and M. Schredl. 2014. The phenomenology of lucid dreaming: An online survey. American Journal of Psychology 127 (2): 191–204. https://doi.org/10.5406/amerjpsyc.127.2.0191 .

Tart, C.T. 1984. Theoretical and Personal Observations. Lucidity Letter 3 (1): 3–5.

Tart, C. T. 1979. From spontaneous event to lucidity: A review of attempts to consciously control nocturnal dreaming. In Wolman, B, H. Ullman, & W. Webb (Eds.), Handbook of Dreams: Research, Theories and Applications (p. 226—268). New York: Van Nostrand Reinhold.

Tholey, P. 1988. Model for lucidity training as a means of self-healing and psychological growth. In Conscious Mind, Sleeping Brain , ed. J. Gackenbach and S.P. Laberge, 263–285. New York: Plenum Press.

Thompson, E. 2014. Waking, Dreaming, Being: Self and Consciousness in Neuroscience, Meditation, and Philosophy. New York: Columbia University Press.

Thompson, E. 2015. Dreamless Sleep, the Embodied Mind, and Consciousness. Open MIND , 37 . https://doi.org/10.15502/9783958570351

Toribio, J. 2007. Nonconceptual Content. Philosophy . Compass 2 (3): 445–460. https://doi.org/10.7551/mitpress/9780262029209.003.0002 .

Van Eeden, F. 1913. A Study of Dreams. Proceedings of the Society for Psychical Research 26: 431–416.

Voss, U., and A. Hobson. 2015. What is the State-of-the-Art on Lucid Dreaming ? Recent Advances and Questions for Future Research. Open Mind 38: 1–20. https://doi.org/10.15502/9783958570306 .

Voss, U., K. Schermelleh-Engel, J.M. Windt, C. Frenzel, and A. Hobson. 2013. Measuring consciousness in dreams: The lucidity and consciousness in dreams scale. Consciousness and Cognition 22 (1): 8–21. https://doi.org/10.1016/j.concog.2012.11.001 .

Voss, U., A. D’Agostino, L. Kolibius, A. Klimke, S. Scarone, and J.A. Hobson. 2018. Insight and dissociation in lucid dreaming and psychosis. Frontiers in Psychology 9 (NOV): 1–9. https://doi.org/10.3389/fpsyg.2018.02164 .

Wallace, B.A. 2012. Dreaming Yourself Awake: Lucid Dreaming and Tibetan Dream Yoga for Insight and Transformation . Boston: Shambhala.

Wangyal, T. 1998. Tibetan Yogas of Dream and Sleep (M. Dahlby, Ed.) . Ithaca: New York, Snow Lion Publications [Ebook].

Williams, P. 1998. The Reflexive Nature of Awareness: A Tibetan Madhyamaka Defence . Delhi: Motitlal Banarsidass.

Windt, J.M. 2010. The immersive spatiotemporal hallucination model of dreaming. Phenomenology and the Cognitive Sciences 9 (2): 295–316. https://doi.org/10.1007/s11097-010-9163-1 .

Windt, J.M., T.A. Nielsen, and E. Thompson. 2016. Does Consciousness Disappear in Dreamless Sleep? Trends in Cognitive Sciences 20 (12): 871–882. https://doi.org/10.1016/j.tics.2016.09.006 .

Windt, J. M., & Metzinger, T. 2007. The philosophy of dreaming and self-consciousness: What happens to the experiential subject during the dream state? In D. Barrett & Pl. McNamara (Eds.), Praeger perspectives. The new science of dreaming: Vol. 3. Cultural and theoretical perspectives (pp. 193–247). Westport, Connecticut; London: Praeger Publishers/Greenwood Publishing Group.

Windt, J. M., & Voss, U. 2018. Spontaneous Thought, Insight, and Control in Lucid Dreams. In Christoff, K. & Fox. K. The Oxford Handbook of Spontaneous Thought: Mind-Wndering, Creativity, and Dreaming. (pp. 387–406). https://doi.org/10.1093/oxfordhb/9780190464745.013.26

Windt, J. M. 2015a. Dreaming: a conceptual framework for philosophy of mind and empirical research . Cambridge, MA: MIT.

Windt, J. M. 2015b. Just in Time—Dreamless Sleep Experience as Pure Subjective Temporality Target Author. In Open MIND , 37. https://doi.org/10.15502/9783958571174 .

Wolman, R.N., and M. Kozmová. 2007. Last night I had the strangest dream: Varieties of rational thought processes in dream reports. Consciousness and Cognition 16 (4): 838–849. https://doi.org/10.1016/j.concog.2006.09.009 .

Worsley, A. 1984. Lucid Dream Definition. Lucidity Letter 3 (2 & 3): 97.

Zahavi, D. 2005. Subjectivity and Selfhood: Investigating the First-Person Perspective . Cambridge, MA: MIT Press.

Book   Google Scholar  

Zink, N., and R. Pietrowsky. 2015. Theories of dreaming and lucid dreaming: An integrative review towards sleep, dreaming and consciousness. International Journal of Dream Research 8 (1): 35–53. https://doi.org/10.13140/RG.2.1.3139.0560 .

Download references

Acknowledgements

This work was supported by the Scottish Graduate School for Arts and Humanities (SGSAH) Doctoral Training Partnership (grant number AH/R012717/1). I owe the inception of this article to Thomas Metzinger, who motivated and supported the original proposal and provided me with further feedback. I’m also indubitably grateful to Fiona Macpherson for continued feedback throughout the different stages of writing this article and to Jennifer Windt for offering further guidance on the critical assessment of her view. I’d also like to thank Alistair Isaac, Melanie Rosen, Graham Doke and Robert Cowan and the members of the Active Mind Lab at the University of Edinburgh, and the audiences of Philosophy, Psychology and Neuroscience seminars at the University of Glasgow for detailed feedback. Finally, thanks to Josh Cox for proofreading assistance.

Author information

Authors and affiliations.

Centre for the Study of the Perceptual Experience, University of Glasgow, 67–69 Oakfield Avenue, Glasgow, UK

Adriana Alcaraz-Sánchez

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Adriana Alcaraz-Sánchez .

Ethics declarations

Conflict of interest.

The author declare that they have no competing financial interests.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Alcaraz-Sánchez, A. Is Lucid Dreamless Sleep Really Lucid?. Rev.Phil.Psych. (2022). https://doi.org/10.1007/s13164-022-00663-9

Download citation

Accepted : 20 October 2022

Published : 04 November 2022

DOI : https://doi.org/10.1007/s13164-022-00663-9

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

  • Find a journal
  • Publish with us
  • Track your research

International Journal of Dream Research

About the journal.

The scope of the journal is to publish peer-reviewed papers in the field of dream research including topics like dream recall, dream content, nightmares, lucid dreaming, dreaming in children and psychological aspects of sleep in general. In addition to empirical papers, comprehensive reviews and book/media reviews are also encouraged.

The IJoDR is indexed in the PsycINFO and Scopus databases.

The International Journal of Dream Research is an open access E-Journal and there is no page charge for authors!

Submitting a paper to the International Journal of Dream Research.

If you want to submit a paper please write an email to the editors ([email protected]) so we can create an account for you. The information regarding the account will be send via email and then you can start the submission process.

The next issue will be published in April 2024 .

The current issue or the online first articles can be assessed directly on this page.

Past issues can be found under the "Archives" heading (see top of the page).

 If you have questions about the Journal then please sent an email to the editors:

Current Issue

research paper about lucid dream

Information

  • For Readers
  • For Authors
  • For Librarians

research paper about lucid dream

Virtual reality training of lucid dreaming

Affiliations.

  • 1 Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands.
  • 2 Department of Psychology, Philipps University, Marburg, Germany.
  • 3 Department of Psychology, University of Zurich, Zurich, Switzerland.
  • 4 IRCCS San Raffaele Pisana, Rome, Italy.
  • 5 Leibniz Institute for Resilience Research, Mainz, Germany.
  • 6 School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
  • 7 Rivierduinen Institute for Mental Healthcare, Leiden, The Netherlands.
  • 8 Technical University Berlin, Germany.
  • 9 Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy.
  • 10 Institute for Management Research, Radboud University, Nijmegen, The Netherlands.
  • PMID: 33308070
  • PMCID: PMC7741087
  • DOI: 10.1098/rstb.2019.0697

Metacognitive reflections on one's current state of mind are largely absent during dreaming. Lucid dreaming as the exception to this rule is a rare phenomenon; however, its occurrence can be facilitated through cognitive training. A central idea of respective training strategies is to regularly question one's phenomenal experience: is the currently experienced world real , or just a dream? Here, we tested if such lucid dreaming training can be enhanced with dream-like virtual reality (VR): over the course of four weeks, volunteers underwent lucid dreaming training in VR scenarios comprising dream-like elements, classical lucid dreaming training or no training. We found that VR-assisted training led to significantly stronger increases in lucid dreaming compared to the no-training condition. Eye signal-verified lucid dreams during polysomnography supported behavioural results. We discuss the potential mechanisms underlying these findings, in particular the role of synthetic dream-like experiences, incorporation of VR content in dream imagery serving as memory cues, and extended dissociative effects of VR session on subsequent experiences that might amplify lucid dreaming training during wakefulness. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Keywords: REM sleep; consciousness; dissociation; lucid dreaming; metacognition; virtual reality.

Publication types

  • Research Support, Non-U.S. Gov't
  • Virtual Reality*

Associated data

  • figshare/10.6084/m9.figshare.c.5215528

U.S. flag

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

  • Publications
  • Account settings
  • Advanced Search
  • Journal List
  • HHS Author Manuscripts

Logo of nihpa

Dreaming and the brain: from phenomenology to neurophysiology

1 Department of Psychiatry, University of Wisconsin, Madison, WI 53719

Giulio Tononi

Associated data.

Dreams are a most remarkable experiment in psychology and neuroscience, conducted every night in every sleeping person. They show that our brain, disconnected from the environment, can generate by itself an entire world of conscious experiences. Content analysis and developmental studies have furthered our understanding of dream phenomenology. In parallel, brain lesion studies, functional imaging, and neurophysiology have advanced our knowledge of the neural basis of dreaming. It is now possible to start integrating these two strands of research in order to address some fundamental questions that dreams pose for cognitive neuroscience: how conscious experiences in sleep relate to underlying brain activity; why the dreamer is largely disconnected from the environment; and whether dreaming is more closely related to mental imagery or to perception.

Contemporary dream research

Although dreams have fascinated us since the dawn of time, their rigorous, scientific study is a recent development[ 1 – 4 ] ( Supplementary Fig. 1 ). In The interpretation of dreams [ 5 ] Freud predicted that “Deeper research will one day trace the path further and discover an organic basis for the mental event.” Recent work, which we review in this article, begins to fulfill Freud s prediction.

The study of dreams is a formidable task, because dream consciousness is only accessible via report rather than direct observation ( Box 1 ) and because it is difficult to manipulate dream content experimentally, whether by exposure to stimuli before[ 6 , 7 ] or during sleep[ 7 , 8 ]. Therefore, it is difficult to predict the contents of specific dreams[ 9 ], and most modern dream research tries to relate neuronal activity retrospectively to dream form rather than dream content, i.e. to focus on properties of all dreams rather than to investigate the neural correlates of a particular dream. Yet, as we shall see, encouraging progress has been made in relating the phenomenology of dreams to underlying brain activity, and to studies of brain damage and development.

BOX 1Can reports be trusted to accurately convey internal experiences in sleep?

Do dream reports obtained by awakening a sleeping subject accurately convey subjective experiences in sleep? At one extreme, we could be fully conscious throughout sleep but remember dreams well, little, or not at all depending on the brain state when we are awakened. Indeed, we know that dreaming often goes unreported – some people claim they rarely dream, but systematic awakenings in sleep labs have revealed that we greatly underestimate how often and how much we are conscious during sleep. On the other hand, neurological patients who report loss of dreaming are no more likely to have memory disorders than those who report dreaming[ 22 ], suggesting that lack of dream reports indeed reflects lack of experience rather than changes in memory alone. Further studies may illuminate this issue since, for example, memory-related regions in the medial temporal lobe are highly active in REM sleep ( Fig. 1 ).

An external file that holds a picture, illustration, etc.
Object name is nihms165848f1.jpg

Meta-analysis of relative increases and decreases in neuronal activity during REM sleep as seen with PET imaging using H2 15 O measurements of regional cerebral blood flow (rCBF) [ 15 , 16 , 19 ] or [ 18 F]-flurodeoxyglucose measurements of glucose metabolism[ 17 ]. Top row: cortical surface, lateral view. Middle row: cortical surface, medial view. Bottom row: subcortical foci (left) and ventral view of cortical surface (right). Analysis is based on published Talairach coordinates of foci whose activity was significant at p<0.001 corrected (Z-score > 3.09). Circles, squares, triangles, and stars denote activity foci as reported by [ 15 ] (Maquet 96), [ 16 ] (Braun 97), [ 17 ] (Nofzinger 97), and [ 19 ] (Maquet 2000), respectively. Each symbol marks a region’s center-of-mass regardless of its spatial extent. Yellow symbols denote increased regional activity in the (1) mesopontine tegmentum and midbrain nuclei, (2) thalamus, (3) basal forebrain and diencephalic structures, (4) limbic MTL structures including amygdala and hippocampus, (5) medial prefrontal cortex, (6) occipito-temporal visual cortex, and (7) anterior cingulate cortex. Cyan symbols denote decreased activity in the (8) orbitofrontal cortex, (9) posterior cingulate and precuneus, (10) dorsolateral prefrontal cortex, and (11) inferior parietal cortex.

At the other extreme, one could claim that we are unconscious throughout sleep and merely have a tendency to confabulate during the transition into wakefulness. While such a claim is hard to refute conclusively (just as it is hard to prove conclusively that one is not a zombie when awake), it seems highly implausible; when one has just experienced a vivid dream, it seems hard to believe that it was made up in a flash during an awakening. Indeed, (a) the estimated time in dream report correlates well with the time elapsed in REM sleep before awakening[ 62 ]; and (b) in REM sleep behavior disorder (where muscle atonia is disrupted), movements seem to match the reported dream[ 113 ].

Reports obtained upon awakenings from deep NREM sleep are more difficult to evaluate because of disorientation associated with increased sleep inertia[ 114 ]. However, some evidence indicates that indeed dream consciousness can occur in NREM sleep and does not merely reflect recalls of earlier REM sleep dreams[ 59 ]: (a) It is sometimes possible to influence dream content by sounds delivered in NREM sleep, and to “tag” NREM reports[ 59 ], (b) Some NREM parasomnias (sleep talking, sleep terrors) correspond to reported dream experiences[ 115 ], and (c) “Full-fledged” dreams are sometimes reported upon awakening from the first NREM episode, before any REM sleep occurred [ 59 , 66 ], and even in naps consisting of only NREM sleep[ 67 ].

Nevertheless, it is worth keeping in mind that several factors may render dream reports less trustworthy when compared to reports of waking experience, including: (a) a dramatic state change, since we report about a sleep experience when awake; (b) considerable time delay, since dream reports are obtained after the experience, possibly leading to passive forgetting and interference; (c) difficulties in verbally describing experiences that are mainly visual and emotional; and (d) censorship of embarrassing, immoral, sexual and aggressive material.

Phenomenology of dreams and their relation to brain activity

The level and nature of our conscious experience varies dramatically in sleep. During slow wave sleep (SWS) early in the night, consciousness can nearly vanish despite persistent neural activity in the thalamocortical system[ 10 ]. Subjects awakened from other phases of sleep, especially but not exclusively during REM sleep, report “typical”, full-fledged dreams - vivid, sensorimotor hallucinatory experiences that follow a narrative structure[ 3 , 11 ]. The dreamer is highly conscious (she has vivid experiences), is disconnected from the environment (she is asleep), but somehow her brain is creating a story, filling it with actors and scenarios, and generating hallucinatory images. How does the brain accomplish this remarkable feat? And, conversely, what do dreams tell us about the organization and working of the brain?

Since awakenings from REM sleep regularly yield reports of typical dreams, we will first focus on neural activity during REM sleep, to gain insight into brain states that are compatible with dreaming. It should be emphasized at the outset, however, that dreams can occur in other brain states, such as late NREM sleep, as will be discussed below.

Similarities between dreaming and waking

In order to gain insight into the phenomenology and neural basis of dreams, it is useful to consider both similarities and differences between waking consciousness and dreaming consciousness, and to relate these differences to changes in brain activity and organization[ 11 ]. Perhaps the most striking feature of conscious experiences in sleep is how altogether similar the inner world of dreams is to the real world of wakefulness. Indeed, at times the dreamer may be uncertain whether he is awake or asleep. Certainly, dreams are not created in a vacuum but closely reflect the organization and functions of our brain.

In most dreams, perceptual modalities and submodalities that dominate in wakefulness are heavily represented. Dreams are highly visual, in full color, rich in shapes, full of movement, and incorporate typical wakefulness categories such as people, faces, places, objects, and animals[ 3 ]. Dreams also contain sounds (including speech and conversation), and more rarely tactile percepts, smells and tastes, as well as pleasure and pain[ 4 , 12 – 14 ]. Experiences in typical dreams have a clear sensory character (i.e. they are seen, heard, and felt) and are not mere thoughts or abstractions.

These phenomenological similarities are reflected in neurophysiological similarities between waking and dreaming. For historical and methodological reasons, most electroencephalogram (EEG) and neuroimaging studies have contrasted brain activity during quiet wakefulness with that observed during REM sleep, when subjects are most likely to report dreams[ 15 – 20 ]. At least superficially, the EEG looks remarkably similar in active waking and REM sleep. Positron emission tomography (PET) studies have shown that global brain metabolism is comparable between wakefulness and REM sleep[ 11 , 20 ]. Such studies have also revealed a strong activation of high-order occipito-temporal visual cortex in REM sleep, consistent with the vivid visual imagery during dreams ( Fig. 1 )[ 16 , 17 , 19 ].

There is also remarkable consistency between a subject s cognitive and neural organization in dreaming and waking[ 13 , 14 ]. For instance, children studies demonstrate that dream features show a gradual development that parallels their cognitive development when awake[ 21 ] ( Box 2 ). Patients with brain lesions that impair their waking cognition show corresponding deficits in dreams. For example, subjects with impaired face perception also do not dream of faces[ 22 , 23 ] ( Box 3 ).

BOX 2The development of dreams in children

When do children start dreaming, and what kind of dreams do they have? Since children often show signs of emotion in sleep, many assume they dream a great deal. However, a series of studies by David Foulkes showed that children under the age of 7 reported dreaming only 20% of the time when awakened from REM sleep, compared with 80–90% in adults[ 21 ].

Preschoolers dreams are often static and plain, such as seeing an animal or thinking about eating. There are no characters that move, no social interactions, very little feeling, and they do not include the dreamer as an active character. There are also no autobiographic, episodic memories, perhaps because children have trouble with conscious episodic recollection in general, as suggested by the phenomenon of infantile amnesia. Preschoolers do not report fear in dreams, and there are few aggressions, misfortunes, and negative emotions. Note that children who have night terrors , in which they awaken early in the night from SWS and display intense fear and agitation, are probably terrorized by disorientation due to incomplete awakening rather than by a dream[ 116 ]. Thus, although children of age 2–5 can obviously see and speak of everyday people, objects and events, apparently they cannot dream of them.

Between ages 5 to 7 dream reports become longer, although still infrequent. Dreams may contain sequences of events in which characters move about and interact, but narratives are not well developed. At around age 7, dream reports become longer and more frequent, contain thoughts and feelings, the child s self becomes an actual participant in the dream, and dreams begin to acquire a narrative structure and to reflect autobiographic, episodic memories.

It could be argued that perhaps all children dream, but some do not yet realize that they are dreaming, do not remember their dreams, or cannot report them because of poor verbal skills. Contrary to these intuitive suggestions, dream recall was found to correlate best with abilities of mental imagery rather than language proficiency. Mental imagery in children is assessed by the Block Design Test of the Wechsler intelligence test battery[ 117 ]. In this task, children look at models or pictures of red and white patterns, and then recreate those patterns with blocks. Critically, scores on this test are the one parameter that correlates best with dream report in children. Put simply, it is children with the most developed mental imagery and visuo-spatial skills (rather than verbal or memory capabilities) that report the most dreams, suggesting a real difference in dream experience. Visuo-spatial skills are known to depend on the parietal lobes, which are not fully myelinated until age 7. Thus, linking visuo-spatial cognitive development with brain maturation studies[ 118 ] is an important field of further research.

The static nature of preschoolers dreams is also in accord with the notion that preoperational children can’t imagine continuous visual transformations[ 119 ]. In the “mental rotation” test[ 120 ] a subject is asked to determine whether two figures are the same or different. In adults, reaction times (which are used as the score) increase linearly with the degree of rotation, but children do not show this relationship and do not seem to be mentally imagining movement using visuo-spatial imagery. This is consistent with their dream reports lacking movement[ 21 ].

Along the same line, people who are blinded after the age of 5–7 seem to have visual imagination and dream with visual imagery throughout life, while blinding at an earlier age leads to absence of visualization in both waking and dreaming[ 121 , 122 ], though dreaming in blind individuals is a subject of debate[ 123 – 125 ]. Overall, dreaming appears to be a gradual cognitive development that is tightly linked to the development of visual imagination.

The slow development of full-fledged dreams and their intimate relation with imagination cast doubts on whether animals can dream as we do. It is likely that animals, too, can be conscious during sleep. For instance, lesions in parts of the brainstem that control movements cause cats to seemingly act out their dreams[ 126 ], very much like humans with REM sleep behavior disorder [ 113 ]. However, while a cat may experience images and emotions in sleep, it is less likely that these experiences are tied together by a narrative as is the case in our typical dreams[ 127 ]. Altogether, what kind of dreaming consciousness an animal has may reflect the extent to which it is conscious in general, and both waking and dreaming consciousness are best viewed as graded phenomena[ 80 ].

BOX 3Lesion studies of dreaming

The primary source on neuropsychology of dreaming is a study by Solms[ 22 ] who examined 361 neurological patients and asked them in detail about their dreaming. Overall, lesion studies indicate that dreaming depends on specific forebrain regions rather than on the brainstem REM sleep generator[ 22 , 128 , 129 ]. In most cases, global cessation of dreaming follows damage in or near the temporo-parieto-occipital junction (around Brodmann’s Area 40), more often unilaterally than bilaterally[ 23 , 128 ]. This region supports various cognitive processes that are essential for mental imagery[ 130 ]. Accordingly, patients with such damage typically show a parallel decline in waking visuo-spatial abilities[ 109 ]. These results strongly suggest that mental imagery is the cognitive ability most related to dreaming (though a link between loss of dreaming and aphasia has also been suggested[ 131 ]).

Less frequently, global cessation of dreaming follows bilateral lesions of white matter tracts surrounding the frontal horns of the lateral ventricles, underlying ventromedial prefrontal cortex[ 22 ]. Many of these nerve fibers originate or terminate in limbic areas, in line with increased limbic activity in REM sleep as revealed by functional imaging[ 15 , 16 , 18 ]. The ventromedial white matter contains dopaminergic projections to the frontal lobe which were severed in prefrontal leucotomy, once performed on many schizophrenic patients[ 53 ]. Most leucotomized patients (70–90%) complained of global cessation of dreaming as well as of lack in initiative, curiosity, and fantasy in waking life[ 23 ]. Since dopamine can instigate goal-seeking behavior, these data have been interpreted as supporting the classical psychodynamic view of dreams as fulfillment of unconscious wishes related to egoistic impulses[ 132 ].

Apart from global cessation of dreaming, more restricted lesions produce the cessation of visual dreaming [ 22 , 109 ], or the disruption of particular visual dimensions in dreams. For example, lesions in specific regions that underlie visual perception of color or motion are associated with corresponding deficits in dreaming[ 23 , 109 ]. In general, it seems that lesions leading to impairments in waking have parallel deficits in dreaming.

Some lesions, especially those in medial prefrontal cortex, the anterior cingulate cortex, and the basal forebrain, are associated with increased frequency and vividness of dreams and their intrusion into waking life[ 22 ]. Importantly, many brain-damaged patients report no changes in dreaming, indicating that the neural network supporting dreaming has considerable specificity. For example, lesions of dorsolateral prefrontal cortex, sensorimotor cortex, and V1 do not seem to affect dreaming at all[ 22 ]. The fact that patients with V1 lesions report vivid dreaming argues against the notion that reentry to early retinotopic cortex is a necessary condition for visual awareness[ 133 ].

Dreams also reflect our interests and personality, just like mental activity during wakefulness. Formal content analysis has revealed that mood, imaginativeness, individuals of interest, and predominant concerns are correlated between our waking and dreaming selves[ 12 – 14 ]. Personal anxieties we experience in wake, such as being inappropriately dressed, being lost, or being late for an examination, can appear in dreams that involve social interactions[ 24 ]. Dreams, like our personality in general, are quite stable over time in adulthood[ 12 – 14 ], and share many characteristics across cultures[ 12 – 14 ]. In addition, we feel we are personally participating in many dream events.

Despite these remarkable similarities, what makes dream consciousness so fascinating are the ways in which it differs from our waking experience. Some of these phenomenological differences are accompanied by consistent neurophysiological differences.

Reduced voluntary control and volition

We are generally surprised on awakening from a dream (“it was only a dream”) mainly because we didn’t consciously will that we would dream it. In fact, during dreaming there is a prominent reduction of voluntary control of action and thought. We cannot pursue goals, and have no control over the dream’s content. The fact that we are so surprised, excited and even skeptical about lucid dreaming – possibly a way to control some dreams[ 25 ] - illustrates how dreams normally lack voluntary control[ 9 ]. Interestingly, recent evidence points to the role of the right inferior parietal cortex (Brodmann’s Area 40) in waking volition[ 26 , 27 ], an area that is deactivated during REM sleep[ 15 , 16 ] ( Fig. 1 ).

Reduced self-awareness and altered reflective thought

Our dreaming consciousness consists of a single “track”: we are not contextually aware of where we are (in bed) or of what we are doing (sleeping, dreaming). There is a strong tendency for a distinct narrative of thoughts and images to persist without disruption (“single-mindedness”[ 28 ]). Indeed, reports of mental activity in REM sleep are longer than reports obtained from awake subjects[ 28 ]. Dreaming is almost always delusional since events and characters are taken for real. Reflective thought is altered in that holding contradictory beliefs is common, and a dreamer easily accepts impossible events such as flying, inconsistent scene switches, sudden transformations and impossible objects[ 29 ] such as a pink elephant. There is often uncertainty about space, time, and personal identities[ 30 ]. For example, a character may have the name, clothes and hairstyle of a male friend, but have mother’s face. Reduced self-monitoring in dreams may be related to the deactivation of brain regions such as posterior cingulate cortex, inferior parietal cortex, orbitofrontal cortex, and dorsolateral prefrontal cortex[ 15 , 16 ] ( Fig 1 ). Indeed, deactivation of prefrontal cortex has been shown to accompany reduced self-awareness during highly engaging sensory perception in wakefulness[ 31 ]. However, some dreams may have conserved reflective thought processes such as thoughtful puzzlement about impossible events[ 32 ], contemplating alternatives in decision-making[ 32 ], reflecting during social interactions[ 32 ], and “theory of mind”[ 33 ], demonstrating that individual dreams can differ from each other substantially.

Emotionality

Some dreams are characterized by a high degree of emotional involvement, including joy, surprise, anger, fear, and anxiety[ 34 – 36 ]. Interestingly, sadness, guilt, and depressed affect are rare[ 11 ], possibly due to reduced self-reflection. Some claim that fear and anxiety are enhanced in dreams to a degree rare in waking life[ 37 ], in line with Freud’s suggestion that dream narratives originate in perceived threats or conflicts[ 5 ]. Whether or not this interpretation has merits, REM sleep is in fact associated with a marked activation of limbic and paralimbic structures such as the amygdala, the anterior cingulate cortex, and the insula[ 15 , 17 , 19 ] ( Fig. 1 ). However, emotions are feeble in other dreams, and are absent altogether in 25–30% of REM sleep reports[ 34 – 36 ], including in situations where emotions would likely be present in waking[ 34 ], once again highlighting the variability in dream phenomenology.

Altered mnemonic processes

Memory is drastically altered for the dream and within the dream. Unless the dreamer wakes up, most dreams are forever lost. Upon awakening, memory for the dream often vanishes rapidly unless written down or recorded, even for intense emotional dreams. It is not clear why this is the case since from a neuroimaging perspective, limbic circuits in the medial temporal lobe that are implicated in memory processes, are highly active during REM sleep[ 15 – 18 ] ( Fig. 1 ). Perhaps the hypoactivity of prefrontal cortex, also implicated in mnemonic processes, plays an important role in dream amnesia. Contemporary theories of dreaming ( Table 1 ) offer different accounts of dream amnesia. For example, according to psychodynamic models, dream amnesia is due to processes of active repression[ 5 ]. According to Hobson s Activation-Input-Mode [AIM] model, dream amnesia is related to a state-change involving inactivity of monoaminergic systems (“aminergic de-modulation”) and deactivation of dorsolateral prefrontal cortex[ 11 ]. The neurocognitive model claims that dreams are usually forgotten because they are internal narratives; unless internal experiences are tied to external cues such as times and places they are bound to be forgotten[ 13 ].

Contemporary theories of dreaming

Episodic memory is also impaired within the dream. Indeed, a dream is not like an episode of life being “replayed”. In one example in which subjects had intensively played the computer game Tetris, there was no episodic memory in subsequent dreams that subjects had indeed played Tetris. In fact, dreams of healthy subjects were indistinguishable from those of profoundly amnesic subjects, who could not remember having played Tetris at all. In contrast, both normal and amnesic subjects often reported perceptual fragments, such as falling blocks on a computer screen, at sleep onset[ 38 ]. While ‘residues’ from waking experience are incorporated in about 50% of dreams[ 39 – 41 ], they do so in new and unrelated contexts, and verified memories for episodes of recent life are only found in about 1.5% of dreams[ 42 ]. Such residual recollections have been interpreted by some to suggest that dreaming may have an active role in forgetting[ 5 , 43 ]. Finally, many have the impression that the network of associations stored in our memory may become looser than in wake[ 44 , 45 ], perhaps favoring creativity, divergent thinking, and problem resolution[ 4 , 46 ].

In summary, dream consciousness is remarkably similar to waking consciousness, though there are several intriguing differences. These include reduced attention and voluntary control, lack in self-awareness, altered reflective thought, occasional hyperemotionality, and impaired memory. Traditionally, dream phenomenology has often been compared to madness or psychosis[ 3 , 11 , 47 ], but in fact the hallucinations, disorientation, and subsequent amnesia of some bizarre dreams may be more akin to the acute confusional state – also known as delirium - which occurs after withdrawal from alcohol and drugs[ 48 ]. However, most dreams are less bizarre, perhaps more similar to mind wandering or stimulus independent thoughts[ 14 , 49 , 50 ]. Waking thoughts jump around and drift into bizarre daydreaming, rumination, and worrying far more than stereotypes of rational linear thinking suggest[ 51 ]. Importantly, individual dreams are highly variable in their phenomenology, and only some conform to the typical monolithic template that is often portrayed. Thus, just like diverse waking experiences, “Not all dreams are created equal” , and future studies should consider different kinds of dreams and their neural correlates separately.

What mechanisms are responsible for regional differences in brain activity between waking and REM sleep, and thus presumably for some of the cognitive differences between waking and dreaming? Single-unit physiology indicates that generally, cortical activity in REM sleep reaches similar levels as found in active wake ( Fig. 2 ), but variability between brain areas remains poorly explored. Regional differences may likely stem from changes in the activity of neuromodulatory systems ( Fig. 2 ). During REM sleep, acetylcholine is alone in maintaining brain activation, whereas monoaminergic systems are silent, an observation that could explain many features of dreams[ 11 ]. For example, consistent with imaging results, cholinergic innervation is stronger in limbic and paralimbic areas than in dorsolateral prefrontal cortex[ 52 ], which may explain why limbic regions are highly active in REM sleep while dorsolateral prefrontal cortex is deactivated ( Fig. 1 ). Dopaminergic modulation may also play a role[ 23 ], since dreaming is decreased by prefrontal leucotomies that cut dopaminergic fibers[ 53 ] and is increased by dopaminergic agonists[ 23 ] ( Table 1 and Fig. 2 ).

An external file that holds a picture, illustration, etc.
Object name is nihms165848f2.jpg

A comparison of cortical activity (upper panel) and neuromodulator activity (bottom panel) in wake, early NREM (when sleep pressure is high and dream reports are rare), late NREM (when sleep pressure dissipates, and dream reports are more frequent), and REM sleep (when dreams are most common).

(a) Intracellular studies. The membrane potential of cortical neurons in both wake and REM sleep is depolarized and fluctuates around −63mV and −61mV, respectively [ 77 ]. In REM sleep, whenever phasic events such as rapid eye movements and PGO waves occur (gray arrows, events not shown), neurons increase their firing rates to levels that surpass those found in wake [ 77 , 146 ]. In early NREM sleep, neurons alternate between two distinct states, each lasting tens/hundreds of milliseconds: UP states (red arrow) are associated with depolarization and increased firing, while in DOWN states (blue arrow) the membrane potential is hyperpolarized around −75mV, and neuronal firing fades[ 78 , 147 ]. Intracellular studies focusing specifically on late NREM sleep are not available (N.A.).

(b) Extracellular studies. Spiking of individual neurons in REM sleep reaches similar levels as in active wake. In both wake and REM sleep, neurons exhibit tonic irregular asynchronous activity [ 77 , 148 – 151 ]. Sustained activity in wake and REM sleep can be viewed as a continuous UP state [ 78 ] (red bars). In early NREM sleep, UP states are short and synchronous across neuronal populations, and are frequently interrupted by long DOWN states (blue bars). In late NREM sleep, UP states are longer and less synchronized [ 79 ].

(3) Polysomnography. Waking is characterized by low-amplitude, high-frequency EEG activity (above 7Hz), occasional saccadic eye movements, and elevated muscle tone. In early NREM sleep, high-amplitude slow waves (below 4Hz) dominate the EEG. Neuronal UP (red) and DOWN (blue) states correspond to positive and negative peaks in the surface EEG, respectively [ 79 ]. Eye movements are largely absent and muscle tone is decreased. In late NREM sleep, slow waves are less frequent, while spindles (related to UP states and surface EEG positivity) become more common. Eye movements and muscle tone are largely similar to early NREM sleep [ 152 ]. In REM sleep, theta activity (4–7 Hz) prevails, rapid eye movements occur, and muscle tone is dramatically reduced.

(d) Neuromodulator activity. Subcortical cholinergic modulation is highly active in wake and REM sleep (green arrows) and leads to sustained depolarization in cortical neurons and EEG activation [ 77 ]. Wake is further maintained by activity of monoamines, histamine, and hypocretin/orexin (green arrows). In sleep, monoaminergic systems including norepinephrine and serotonin reduce their activity (pink arrows), and are silent in REM sleep (red arrows). While dopamine levels do not change dramatically across the sleep-wake cycle (asterisks), phasic events and regional profiles may differ[ 153 ].

Data are pooled across different species for illustration purposes. Intracellular cat data adapted with permission from Ref [ 77 ]; extracellular and EEG rat data obtained from V. Vyazovskiy (personal communication).

On the whole, relating typical dreams to the neurophysiology of REM sleep has proven to be a useful starting point for revealing the neural basis of dreaming. However, dream consciousness can not be reduced to brain activity in REM sleep. Indeed, some fundamental questions concerning the relationship between the brain and dreaming linger on. We shall discuss three in turn: i) what determines the level of consciousness during sleep; ii) why the dreamer is disconnected from the environment; and iii) whether dreams are more akin to perception or to imagination.

What determines the level of consciousness during sleep?

In principle, studying mental experiences during sleep offers a unique opportunity to explain how changes in brain activity relate to changes in consciousness[ 3 , 54 ]. In fact, if it were not for sleep, when consciousness fades in and out on a regular basis, it might be hard to imagine that consciousness is not a given, but depends somehow on the way our brain is functioning. Traditionally, studies have focused on differences among reports obtained after awakenings from different sleep stages or at different times of night. When REM sleep was initially distinguished from NREM sleep[ 55 ], it was reported that 74–80% of REM sleep awakenings produced vivid dream recall, compared to only 7–9% of awakenings from NREM sleep[ 56 , 57 ]. It was only natural to conclude that, compared to NREM sleep, the distinct physiology of REM sleep, and especially its fast, low-voltage EEG resembling that of wakefulness, was the reason why we are conscious and dream in REM sleep, and not in NREM sleep[ 29 ]. Indeed, for some time, reports of mental activity upon awakenings from NREM sleep were assumed to be recalls of earlier REM sleep dreams, or considered analogous to sleep talking[ 3 ], or treated as confabulations made up by subjects confused upon awakening[ 9 ] ( Box 1 ). However, when changing the question from “tell me if you had a dream” to “tell me anything that was going through your mind just before you woke up,” reports of conscious experiences in NREM sleep ranged between 23% and 74%[ 9 ]. Subsequent studies demonstrated clearly that NREM sleep awakenings yielded reports of mental activity[ 58 , 59 ].

Specifically, reports from sleep stage N1 are extremely frequent (80–90% of the time), though they are very short[ 60 ]. Usually people report vivid hallucinatory experiences, so-called hypnagogic hallucinations . In contrast to typical dreams, hypnagogic hallucinations are often static - like single snapshots[ 11 , 47 ], and usually do not include a self character[ 14 ]. Some activities performed before sleep (e.g. video games) may influence the content of hypnagogic dreams[ 38 , 61 ]. Awakenings from NREM sleep stages N2 and N3 yield reports about some experienced content 50–70% of the time[ 59 ], although there is great variability throughout the night and between subjects. Early in the night, when stage N3 is prevalent and many large slow waves dominate the EEG, awakenings yield few reports[ 62 ]. Moreover, these reports are often qualitatively different than typical REM sleep reports, being usually short, thought-like, less vivid, less visual and more conceptual, less motorically animated, under greater volitional control, more plausible, more concerned with current issues, less emotional and less pleasant[ 9 , 11 , 63 ]. Also, the average length of REM sleep reports increases with the duration of the REM sleep episode while this is not true for NREM sleep reports[ 62 ]. However, late in the night NREM sleep reports are considerably longer and more hallucinatory. Indeed, 10–30% of all NREM sleep reports are indistinguishable by any criteria from those obtained from REM sleep[ 64 , 65 ]. Since NREM sleep accounts for 75% of total sleep time, this means that full-fledged NREM sleep dreams actually account for a significant portion of all typical dreams.

Thus, the initial equation of a physiological state (REM sleep) with a mental state (dreaming) was incorrect, or at best, an oversimplification. Moreover, neuropsychological evidence indicates that dreaming and REM sleep can be dissociated: forebrain lesions may abolish dreaming and spare REM sleep, whereas brainstem lesions may nearly eliminate overt features of REM sleep without abolishing dreams[ 23 ] ( Box 3 ). But if dream reports can be elicited during any stage of sleep[ 11 , 47 , 59 , 66 , 67 ], and conversely some awakenings may yield no report, no matter in which sleep stage they were obtained[ 59 ], where do we stand today with respect to the relationship between brain activity and consciousness during sleep?

The one thing that seems clear is that we need to move beyond the REM/NREM sleep dichotomy and beyond traditional sleep staging. Though staging is useful, it treats brain activity as uniform in space (only a few electrodes are used) and in time (for 30 sec epochs). Inevitably, subtler features of brain activity, which may well influence the presence, degree, and reportability of consciousness, are missed both in space and in time.

In the spatial domain, increasing evidence suggests that different brain regions may be in different states at the same time. For example, preliminary findings suggest that during sleepwalking, thalamocingulate pathways may be active as in wake, while the rest of the cerebral cortex is in NREM sleep[ 68 ]. A related notion of dissociated states is derived from the study of parasomnias, where wake-like behaviors occur during sleep[ 69 ]. For instance, the study of REM sleep behavior disorder shows that, contrary to common assumptions, wakefulness, REM sleep and NREM sleep may not be mutually exclusive states[ 69 ]. In the current context, it has been suggested that dreaming in NREM sleep is related to ‘covert’ REM processes that occur locally[ 59 ]. Thus, refined spatial analysis using fMRI or high-density EEG (hd-EEG) could potentially identify regionally-specific predictors of dreaming, and possibly indicate, in real time, whether dream reports will be obtained.

In the temporal domain, some attempts have been made to relate transient, phasic activities[ 70 ] to dreaming. For example, various studies have tried to link dream recall to eye movements[ 71 , 72 ], PGO waves[ 73 ], and EEG power bouts in specific frequency bands[ 74 ] but limited success has been achieved, and little has been done for NREM sleep[ 11 , 75 , 76 ]. We now know that slow waves in NREM sleep reflect a slow oscillation of cortical neurons between UP and DOWN states ( Fig. 2 )[ 77 , 78 ]. Perhaps long UP states are necessary for dreaming to occur. This is normally the case in REM sleep since slow waves are absent. As for NREM sleep, we would expect that higher occurrence of recalls, and especially of typical dreams in the morning hours, would reflect longer UP periods upon dissipation of sleep pressure ( Fig. 2 )[ 79 ]. In general, focusing on (rather than avoiding) “gray zones” where it is more difficult to predict whether a dream report will be obtained, for example in early REM sleep or late NREM sleep, may be a promising strategy for identifying psychophysiological correlates that go beyond traditional staging.

Finally, theoretical considerations suggest that the level of consciousness may depend on the brain s ability to integrate information[ 80 ]. Indeed, during wakefulness external perturbations such as TMS pulses (transcranial magnetic stimulation) cause changing patterns of activation across distant interconnected brain regions[ 10 ]. In REM sleep, evoked activity propagates much like it does in wakefulness[ 81 ]. By contrast, in deep SWS early in the night, when consciousness is most likely to fade, the response evoked by TMS remains either local (loss of integration), or spreads nonspecifically (loss of information). Apparently, the brain s capacity for information integration is reduced whenever neurons become bistable between UP and DOWN states. Intriguingly, the brain s response to a TMS pulse may offer a more sensitive measure of the inner state than spontaneous EEG. For example, such perturbations can uncover inherent bistability in short stretches of NREM sleep even when the EEG shows a wake-like low-voltage pattern[ 82 ].

Why is the dreamer disconnected from the environment?

The most obvious difference between dreaming and waking consciousness is the profound disconnection of the dreamer from his current environment. Such disconnection, of course, is a key feature of sleep: by definition a sleeping person shows no meaningful responses to external stimuli, unless they are strong enough to cause an awakening. This feature is known as “high arousal threshold”, and it persists in REM sleep despite its wake-like low-voltage EEG[ 83 ]. Moreover, stimuli not only fail to elicit a behavioral response, but also largely fail to be incorporated in the content of the dream[ 8 , 84 – 86 ] (though some stimuli, such as a spray of water, pressure on the limbs, and meaningful words have a slightly higher chance of incorporation[ 84 , 85 ]). This striking disconnection occurs even when subjects sleep with their eyes taped open and objects are illuminated in front of them[ 8 ]. Surely just before awakening, stimuli such as the sound of an alarm clock can enter our dreams, but when sleep is preserved, such relations are by and large surprisingly weak and dream consciousness is remarkably disconnected from the external environment.

The disconnection of the dreamer poses an intriguing paradox, especially if one considers that dreams involve vivid sensory experiences, and that they can occur upon a state of strong cortical activation. Several possibilities come to mind. For example, it has been suggested that during sleep a thalamic “gate” may close and sensory inputs may not reach the cortex effectively[ 87 ]. However, evoked responses in primary sensory cortices are largely preserved during REM sleep[ 88 , 89 ]. Also, olfactory stimuli are not directly incorporated in dreams[ 90 ], though they are not routed through the thalamus (their emotional valence, however, may affect dreams). A related notion is that of a cortical “gate” leading to diminished inter-cortical propagation[ 91 ], as seems to be the case in the dissociation of primary visual cortex (V1) from high-order visual cortex in REM sleep[ 18 ]. It would be interesting to establish whether direct activation of cortical areas can overcome the disconnection from the environment. For example, can TMS over V1 or area MT bypass thalamic or cortical “gates” and produce sensations of phosphenes or movement in dream consciousness?

An intriguing possibility concerns the putative antagonism between externally oriented cortical networks and internally oriented, default-mode networks[ 92 , 93 ]. Perhaps in dreams intrinsic activity dominates, as it does during stimulus-independent thoughts in wake[ 50 ]. This may occur at the expense of the processing of external stimuli, leading to disconnection from the environment. Indeed, both PET and magnetoencephalography (MEG) suggest that medial prefrontal cortex, a part of the default network, is highly active in REM sleep[ 16 , 17 , 94 ] as it is during wakeful rest ( Fig. 1 ). Conversely, other components of the default network, including posterior cingulate and inferior parietal cortices, are deactivated in REM sleep[ 15 , 16 ], as in highly-engaging waking tasks ( Fig. 1 ). The exact cognitive task associated with the default-mode network is still not well understood[ 95 ] and it may be primarily driven by self-related introspective processes rather than general mind wandering[ 31 , 96 , 97 ]. Indeed, since most nodes of this network are deactivated in REM dreaming and mental imagery[ 98 ], cognitive states that are oriented internally but away from the self do not seem sufficient to elicit activity in this network.

Another possibility is that dreams may be analogous to altered states of consciousness in which attention is profoundly altered, as may be the case in extreme absorption, hypnosis, neglect[ 99 ], and Balint s syndrome, when visual experience may persist for single but unlocalizable objects (simultanagnosia)[ 100 , 101 ]. The reticular thalamic nucleus has been implicated in redirecting attention across modalities[ 102 , 103 ] and its activity in sleep may underlie some aspects of disconnection. It would also be interesting to determine whether neuronal correlates of momentary lapses of attention[ 104 ] occur regularly while dreaming.

Finally, as we have seen, the neuromodulatory milieu changes drastically in sleep ( Fig. 2 ). Specifically, the levels of norepinephrine, serotonin, histamine, and hypocretin are greatly reduced in REM sleep compared to wake, so the presence of one or more of these neuromodulators may be necessary for external stimuli to be incorporated into our stream of consciousness. This search can be narrowed down by considering cataplexy, which affects people with narcolepsy[ 105 ]. Cataplexy is a transient episode of muscle tone loss in which humans report that awareness of external stimuli is preserved, and presumably animals are likewise aware of their environment during cataplectic attacks. Neuromodulatory activity in cataplectic dogs is largely similar to that in REM sleep except that levels of histamine are high, much like during wakefulness[ 105 ]. It thus seems that levels of histamine are correlated with our ability to incorporate sensory stimuli into conscious experience. It would be important to establish whether histamine is indeed necessary for such incorporation, and how it may do so. For instance, could it be that in wakefulness histaminergic tone facilitates transmission of feed-forward sensory inputs in cortical layer 4, at the expense of backward signal propagation?

Are dreams more like perception or imagination?

Whether dreams are generated in a “bottom-up” or a “top-down” manner is a question that has been asked since at least Aristotle[ 106 ]. To put the question in a modern context, do dreams start from activity in low-level sensory areas, which is then interpreted and synthesized by higher-order areas, as is presumably the case in waking perception? Or do they begin as wishes, abstract thoughts, and memories deep in the brain, which are then enriched with perceptual and sensory aspects, as in imagination? Of course, it is possible that such a dichotomy is misguided, and dreams may be best conceptualized as global attractors that emerge simultaneously over many brain areas. However, as we shall see, the available data do indeed suggest that there may be a privileged direction of dream generation.

In the 19th century, sensory experience was often regarded as the source of dreams, which were considered to be an attempt of the mind to interpret somatic nerve-stimuli ( Supplementary Fig. 1 ). A similar notion was later adopted by Henri Beaunis, and recently championed by Allan Hobson ( Table 1 )[ 4 , 11 , 47 ]. According to his AIM model, internally generated signals originating in the brainstem during REM sleep, such as PGO waves, excite visual cortex and are later processed and synthesized by higher-order areas. High levels of acetylcholine in the absence of aminergic neuromodulation may enhance feed-forward transmission and suppress back-propagation[ 3 , 107 ]. By contrast, Freud and some of his followers asserted that dreams originate from psychic motives that are later instantiated as sensory percepts, much like mental imagery[ 5 ].

Deciding between these alternative views will most likely require difficult experiments in which the direction of signal flow during dreaming sleep is evaluated and compared to that during waking perception and imagery[ 108 ] ( Box 4 ). However, various lines of evidence already suggest that dreaming may be more closely related to imagination than to perception. From lesion studies ( Box 3 ) we know that dreaming requires an intact temporo-parieto-occipital junction[ 22 , 23 ] and lesions in this region also affect mental imagery in wakefulness[ 109 ]. Cognitive studies indicate that the skill that maximally correlates with dream recall in adults is visuo-spatial imagery[ 110 ]. In children, dream recall develops hand in hand with visuo-spatial imagery ( Box 2 ). In epileptic patients, direct electrical stimulation in high-order regions such as the medial temporal lobe, rather than in visual cortex, can elicit “dream-like” experiences[ 111 ], although such patients are simultaneously aware of their surroundings. Other evidence comes from lucid dreamers[ 25 ] who report that it is impossible to focus on fine-grain details of visual objects, as is the case in mental imagery[ 112 ]. Perhaps top-down connections lack the anatomical specificity to support detailed representations. The rare occurrences of smells or pain in dreams may also be related to our difficulty in imagining them vividly when awake. However, one important difference between dreaming and mental imagery is that while imagining we are aware that the images are internally generated (preserved reflective thought).

Box 4Future directions

1. Signal propagation in dreams

During wakefulness, sensory responses precede responses in higher-order areas by more than 100ms[ 134 , 135 ]. Does neural activity during dreaming sleep show a similar feed-forward progression as in perception? Or does neural activity propagate backwards, from higher to lower areas, as it is thought to do during imagery? This issue, which is crucial to our understanding of dream generation, could be resolved by examining unit and field potential recordings from the same neuronal populations in wake and REM (or late NREM) sleep in both animals and humans[ 135 ]. One can also apply directional measures of signal propagation (e.g. Granger causality) to hd-EEG data, and check whether the main direction of signal flow inverts between wake and sleep. Finally, one could use TMS with concurrent hd-EEG during both wake and REM sleep, and examine whether there may be a preferential direction of the brain s response to perturbations depending on behavioral state[ 10 ].

2. Functional networks underlying dreaming

So far, most regional studies of brain activity during sleep have employed PET. While PET allows for quantification of cerebral blood flow and comparison across vigilance states, functional MRI (fMRI) offers superior spatial and temporal resolutions. Event-related fMRI has been already used to map brain activity associated with phasic events such as slow waves[ 136 ] and eye movements[ 137 , 138 ]. Studies of functional and effective connectivity[ 139 ] may be especially well suited to map the functional networks underlying dreaming. Notably, perceptual awareness is associated with specific functional connectivity patterns within sensory modalities[ 140 ], between modalities[ 141 ], and with a striking segregation between sensory systems and the default-mode/intrinsic system[ 31 , 93 , 104 ]. Are such connectivity patterns also a hallmark of activity in the dreaming brain? What regional brain activity underlies dreaming in NREM sleep? How do functional networks of mental imagery and dreaming compare in the same subjects? Finally, hd-EEG may be particularly suited for sleep imaging since it (a) allows for relatively undisturbed sleep, (b) upon source modeling can provide a spatial resolution roughly comparable to PET, (c) offers high temporal resolution suitable for evaluating signal propagation, and (d) can be combined with TMS during sleep.

3. Initial steps towards studying dream content

Progress in signal decoding may ultimately enable us to investigate the neural correlates not only of dream form – what is common to all dreams – but also of dream content – what is specific to a particular dream. This can be done, for instance, by using classification techniques applied to fMRI or hd-EEG data[ 142 ]. At least initially, it may be worthwhile to consider some coarse properties of individual dreams, such as the frequency of occurrence of faces or places in a dream report, the amount of movement, or the dominant affective valence. In principle, it should be possible to predict not only the likelihood of a report upon awakening, but also the likelihood of specific features based on preceding brain activity. An important step in this direction would be to identify the contents of internally generated mental imagery using the same approach[ 143 ]. Furthermore, some patients with epilepsy or post-traumatic stress disorder who experience recurring dream contents[ 144 , 145 ] may provide a unique opportunity to relate specific dream content to its neural basis.

If the flow of brain activity during dreaming were shown to be largely backwards, as one would expect in imagery, rather than forwards, as in perception, many of the seemingly bizarre properties of dreams, such as blended characters and scene switches, would be easier to explain, as they are standard features of our imagination. Such a top-down mode may disrupt the encoding of new memories, and thus underlie dream amnesia. In addition, top-down mental imagery could obstruct the processing of incoming stimuli and disconnect us from the environment. If this view is correct, waking consciousness is more like watching the news in real time, while dreaming is more like watching a movie created by an imaginative director[ 81 ]. As in some B-movies, the director is not particularly choosey and any actor, dress, means of transportation, or object that is readily available will do. Albert Einstein said that “imagination points to all we might yet discover and create”, and indeed, dreaming may turn out to be the purest form of our imagination.

Concluding remarks

In summary, dream consciousness is remarkably similar to waking consciousness, though there are several intriguing differences in volition, self-awareness and reflection, affect, and memory, and there is great variability between individual dreams. The neurophysiology of REM sleep, and in particular recent insights into its regional activity patterns, offers a useful starting point for relating dream phenomenology to underlying brain activity. However, the initial equation of REM sleep with dreaming has been shown to be inaccurate. Thus, it is time we moved beyond sleep stages when trying to link dream consciousness to neuronal events, and focused on more subtle features of brain activity in space and time. Our profound disconnection from the external environment when dreaming poses a central unsolved paradox, the answer to which may be instrumental for understanding dreams. Converging evidence from multiple fields of study, including phenomenology, development, neuropsychology, functional imaging, and neurophysiology, support the notion that dreaming may be closely related to imagination, where brain activity presumably flows in a “top-down” manner. Viewing dreams as a powerful form of imagination can help explain many of their unique features, such as sudden transitions, uncertainty about people and places, poor subsequent recall, disconnection from the environment, and offers testable predictions for future studies.

Supplementary Material

Acknowledgments.

We apologize to those whose work was not cited because of space constraints. We thank Michal Harel, Lior Fisch, and Vlad Vyazovskiy for help with figures; Chiara Cirelli, Rafi Malach, Simone Sarasso, Brady Riedner, and Fabio Ferrarelli for helpful discussions and comments; our anonymous reviewers for valuable suggestions. Y.N. is supported by an EMBO long term fellowship and the Brainpower for Israel Fund. G.T is supported by an NIH Director’s Award DP1 OD000579 and NIH Conte Center Award P20 MH077967.

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

IMAGES

  1. (PDF) Applications of lucid dreams and their effects on the mood upon

    research paper about lucid dream

  2. Paper Lucid Dreams

    research paper about lucid dream

  3. How To Lucid Dream For Beginners In 7 Easy Steps

    research paper about lucid dream

  4. Research Paper Lucid Dreaming

    research paper about lucid dream

  5. (PDF) Lucid Dreaming, Psychic Development, and Spirituality

    research paper about lucid dream

  6. Lucid Dreams: When They Occur and How to Have Them

    research paper about lucid dream

VIDEO

  1. Lucid Dreams #juicewrld #legendsneverdie #lucid dreams #edit #notemplate

  2. IASD 40th anniversary Research talk series Daniel Erlacher Lucid dreaming March 11 2023 ed

  3. HOW TO LUCID DREAM EASILY (do it tonight!)

  4. Lucid Dream Price $ مميزات افخم سياره كهربائيه

  5. The Lucid Dream Machine

  6. How to lucid dream! 😱

COMMENTS

  1. The cognitive neuroscience of lucid dreaming

    A focus of research is also to develop methods to induce lucid dreams. Combining training in mental set with cholinergic stimulation has shown promising results, while it remains unclear whether electrical brain stimulation could be used to induce lucid dreams.

  2. Findings From the International Lucid Dream Induction Study

    ORIGINAL RESEARCH article Front. Psychol., 16 July 2020 Sec. Consciousness Research Volume 11 - 2020 | https://doi.org/10.3389/fpsyg.2020.01746 This article is part of the Research Topic "Is this a Dream?" - Evolutionary, Neurobiological and Psychopathological Perspectives on Lucid Dreaming View all 17 articles

  3. Lucid Dreaming: A State of Consciousness with Features of Both Waking

    Lucid dreaming is a dissociated state with aspects of waking and dreaming combined in a way so as to suggest a specific alteration in brain physiology for which we now present preliminary but intriguing evidence.

  4. Cognitions in Sleep: Lucid Dreaming as an Intervention for Nightmares

    Lucid dreaming (LD) is a learnable and effective strategy to cope with nightmares and has positive effects on other sleep variables. In LDs, the dreamer is aware of the dreaming state and able to control the dream content. The aim of this study is to evaluate the effectiveness of lucid dreaming therapy (LDT) in patients suffering from PTSD.

  5. The cognitive neuroscience of lucid dreaming

    10.1016/j.neubiorev.2019.03.008 Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for decades, the neurobiology of lucid dreaming is still incompletely characterized.

  6. Induction of lucid dreams: A systematic review of evidence

    According to him, (1)-(4) are indispensible prerequisites of lucid dreaming. While in this paper we will follow the conventional minimal criterion for the definition ... But both to progress lucid dream research and make lucid dreaming available to wider populations, reliable induction techniques must be established. ...

  7. A systematic review of new empirical data on lucid dream induction

    Lucid dreams can be elicited either from the state of being awake or from the state of dreaming (LaBerge, 1986).Researchers named lucid dreams elicited from the state of being awake as 'wake-initiated lucid dreams' (WILD) and named those elicited from the state of dreaming as 'dream-initiated lucid dreams' (DILD) (LaBerge et al., 1986).For the latter, most are detected or can be ...

  8. Induction of lucid dreams: a systematic review of evidence

    Lucid dreaming is a learnable skill and a variety of techniques is suggested for lucid dreaming induction. This systematic review evaluated the evidence for the effectiveness of induction techniques. A comprehensive literature search was carried out in biomedical databases and specific resources.

  9. The role of mindful acceptance and lucid dreaming in nightmare ...

    In Study 1, less than one-third of the participants reported having one or more lucid dreams per month, which classifies them as frequent lucid dreamers 98.The FMI score mean was 36.46 (SD = 5.98).

  10. Wake Up, Work on Dreams, Back to Bed and Lucid Dream: A Sleep

    Lucid dreaming offers many opportunities to study consciousness processes. However, laboratory research in this area is limited because frequent lucid dreamers are rare. Several studies demonstrated that different methods of induction could increase the number of lucid dreams.

  11. Here's what lucid dreamers might tell us about our sleeping minds

    Lucid dream research "has been enjoying a renaissance over the last decade," says neuroscientist Tore Nielsen. He directs the Dream & Nightmare Laboratory at the Center for Advanced Research ...

  12. (PDF) Lucid Dreaming: a Mysterious Phenomenon

    Introduction Lucid Dream (LD) is a phenomenon occurring at the end of REM sleep and during which one is aware that one is dreaming. It is possible thanks to the activation of the dorsolateral...

  13. (PDF) Bridging lucid dream research and transpersonal psychology

    Bridging Lucid Dream Research and Transpersonal Psychology Bogzaran (2003) delineates hyperspace lucidity'' - a somewhat ineffable lucid nded and disintegrated, which deals mostly with...

  14. Lucid dreaming: a state of consciousness with features of both waking

    Lucid dreaming is a dissociated state with aspects of waking and dreaming combined in a way so as to suggest a specific alteration in brain physiology for which we now present preliminary but intriguing evidence. We show that the unusual combination of hallucinatory dream activity and wake-like reflective awareness and agentive control ...

  15. Sleep fragmentation and lucid dreaming

    Here we investigate the association between sleep fragmentation and lucid dreaming, with a multi-centre study encompassing four different investigations into subjective and objective measures of sleep fragmentation, nocturnal awakenings, sleep quality and polyphasic sleep schedules.

  16. Are Lucid Dreams Good for Us? Are We Asking the Right Question? A Call

    A Call for Caution in Lucid Dream Research Nirit Soffer-Dudek * Author information Article notes Copyright and License information PMC Disclaimer Lucid dreams (LD), i.e., dreams in which one is cognizant of the fact that one is dreaming, have become well-known in recent years, and their deliberate induction has become widespread.

  17. Is Lucid Dreamless Sleep Really Lucid?

    2.1 Views on Lucidity in Lucid Dreaming Research. Since the inception of the term 'lucid dreaming' by Van Eeden (), LDs are described as those dreams in which one knows that one is dreaming (Gillespie 1983; Green 1968; LaBerge 1985).However, in the literature, we find slightly different characterisations as to what this 'knowing that one is dreaming' amounts to.

  18. International Journal of Dream Research

    The scope of the journal is to publish peer-reviewed papers in the field of dream research including topics like dream recall, dream content, nightmares, lucid dreaming, dreaming in children and psychological aspects of sleep in general. In addition to empirical papers, comprehensive reviews and book/media reviews are also encouraged.

  19. (PDF) Dreams and Psychology

    Research suggests that the brain undergoes a physiological change during lucid dreaming. In In fMRI studies, the prefrontal cortex and a cortical network including the frontal, parietal, and

  20. Is It a Good Idea to Cultivate Lucid Dreaming?

    Lucid dreaming (LD) is the process of being aware that one is dreaming while dreaming. In some cases, the dreamer may even gain control over a part of the dream plot and scenery.

  21. Virtual reality training of lucid dreaming

    A central idea of respective training strategies is to regularly question one's phenomenal experience: is the currently experienced world real, or just a dream? Here, we tested if such lucid dreaming training can be enhanced with dream-like virtual reality (VR): over the course of four weeks, volunteers underwent lucid dreaming training in VR ...

  22. The Role of Dreams in the Evolution of the Human Mind

    This paper presents an evolutionary argument for the role of dreams in the development of human cognitive processes. While a theory by Revonsuo (2000) proposes that dreams allow for threat rehearsal and therefore provide an evolutionary advantage, the goal of this paper is to extend this argument by commenting on other fitness-enhancing aspects ...

  23. Dreaming and the brain: from phenomenology to neurophysiology

    It is now possible to start integrating these two strands of research in order to address some fundamental questions that dreams pose for cognitive neuroscience: how conscious experiences in sleep relate to underlying brain activity; why the dreamer is largely disconnected from the environment; and whether dreaming is more closely related to men...