Sleep
September 1, 2009
Ursula Voss, R. Holzmann, Inka Tuin et al.
443 citations
Lucid dreaming combines hallucinatory dream activity with wake-like reflective awareness and control. Electrophysiological recordings from six trained student volunteers show that lucid dreaming shares REM-like power in delta and theta frequency bands but exhibits higher-than-REM activity in the gamma band, peaking around 40 Hz, especially in frontal and frontolateral regions. Overall brain coherence during lucid dreaming resembles waking levels and is significantly higher than in REM sleep across the analyzed spectrum; waking shows high alpha coherence, while lucid dreaming shows increased delta and theta coherence, largest in frontolateral and frontal areas. These findings suggest lucid dreaming is a hybrid state of consciousness with measurable physiological differences from both waking and REM sleep.
Sleep
August 29, 2014
Jason C Ong, Rachel Manber, Zindel V. Segal et al.
338 citations
Mindfulness meditation reduces chronic insomnia symptoms. In a three-arm trial, 54 adults with chronic insomnia were randomly assigned to mindfulness-based stress reduction (MBSR), mindfulness-based therapy for insomnia (MBTI), or self-monitoring (SM). Those receiving either meditation intervention showed significantly greater reductions in total wake time (43.75 vs 1.09 minutes), pre-sleep arousal (7.13 vs 0.16 points), and insomnia severity (4.56 vs 0.06 points) from baseline to post-treatment compared to SM. At 6-month follow-up, MBTI produced greater insomnia severity reductions than MBSR, with 50% remission and 78.6% response rates. Mindfulness meditation offers a viable treatment alternative for chronic insomnia.
Sleep
June 29, 2012
Martin Dresler, Renate Wehrle, Victor I. Spoormaker et al.
271 citations
Lucid dreaming—being aware that one is dreaming—is associated with reactivation of brain areas that are normally deactivated during REM sleep. In one experienced lucid dreamer who had two episodes of verified lucid REM sleep long enough for fMRI analysis, the bilateral precuneus, cuneus, parietal lobules, and prefrontal and occipito-temporal cortices showed strong activation compared with non-lucid REM sleep. This pattern may explain the return of reflective cognitive abilities that characterize lucid dreaming.
Sleep
February 27, 2015
Pauline Dodet, Mario Chávez, Smaranda Leu-Semenescu et al.
115 citations
People with narcolepsy are far more likely to experience lucid dreaming—being aware that they are dreaming while still asleep—than healthy individuals. In a case-control study, 77.4% of 53 narcolepsy patients reported having lucid dreams, compared to 49.1% of 53 controls, averaging 7.6 lucid dreams per month versus 0.3. During monitored naps, 7 of 12 narcoleptic frequent lucid dreamers (but none of 5 controls) successfully signaled from a lucid REM sleep state. Brain wave analysis showed lower delta, theta, and alpha power and reduced frontal coherence during lucid versus non-lucid REM sleep, along with longer REM duration. The findings suggest narcolepsy provides a useful model for studying lucid dreaming.
Sleep
September 1, 1993
Richard P. Allen, Una D. Mccann, George A. Ricaurte
113 citations
MDMA, a recreational drug that damages serotonin neurons in animals, is linked to persistent sleep disturbances in humans. Comparing all-night sleep recordings of 23 MDMA users with 22 matched controls, MDMA users averaged 19 minutes less total sleep and 23.2 minutes less non-REM (NREM) sleep, primarily due to 37 minutes less stage 2 sleep. No significant differences appeared in stages 1, 3, or 4. While the cause—whether serotonin neurotoxicity—remains unknown, the findings suggest MDMA use can lead to lasting changes in brain structures governing sleep.
Sleep
April 30, 2015
Michael Rak, P. Beitinger, Axel Steiger et al.
56 citations
People with narcolepsy recall dreams and nightmares significantly more often than healthy controls, and they also experience lucid dreaming—awareness of dreaming during a dream—at a much higher rate. Among 60 narcolepsy patients and 919 controls, narcolepsy patients reported roughly double the frequency of dream recall and nightmares, and their lucid dreaming frequency was about four times higher. Most narcolepsy patients who had experienced lucid dreaming said it helped relieve the distress from nightmares. Medication did not affect lucid dreaming frequency, though it did reduce dream recall and nightmare frequency.
Sleep
April 11, 2022
Benjamin Baird, Giulio Tononi, Stephen LaBerge
41 citations
Lucid dreaming is not a hybrid state mixing sleep and wakefulness, as previously claimed based on increased 40 Hz brain activity. The apparent rise in frontolateral 40 Hz power during lucid REM sleep is actually an artifact caused by saccadic spike potentials from heightened eye movement density. In a reanalysis of 14 signal-verified lucid dreams from six participants, lucid REM sleep showed higher REM density than baseline REM sleep, but no difference in 40 Hz power after removing the spike potential artifact. Lucid REM also showed small reductions in low-frequency and beta band power and increased signal complexity, all within normal REM sleep variation. Lucid dreams involve higher physiological activation, including subcortical and cortical measures.
Sleep
May 14, 2021
Laura Sophie Imperatori, Jacinthe Cataldi, Monica Betta et al.
30 citations
Functional connectivity metrics, which describe how brain regions interact, can reveal differences across stages of sleep and wakefulness that power-based analyses alone may miss. Analyzing overnight sleep and resting-state wakefulness recordings from 24 healthy adults, the study found that combining power features with two connectivity measures—weighted Phase Lag Index (wPLI) and weighted Symbolic Mutual Information (wSMI)—improved the accuracy of classifying four vigilance stages (wakefulness, NREM-N2, NREM-N3, and REM sleep) compared to using any single feature type. Delta-band connectivity (0.5–4 Hz) was most important across all classifications, suggesting slow waves play a role in consciousness and sensory disconnection.
Sleep
December 13, 2018
Dan Denis, Giulia Poerio, Sarah Derveeuw et al.
25 citations
Exploding head syndrome, a sensory parasomnia where people perceive loud noises or a sense of explosion when falling asleep or waking, affects about 10-15% of individuals, with significant fear in some cases. Across two samples—199 female undergraduates and 1,683 international participants aged 18-82—lifetime prevalence was 37.19% and 29.59%, respectively, with monthly episodes in 6.54% and 3.89%. Insomnia symptoms and sleep paralysis frequency were consistently linked to the condition in multiple logistic regression models. In the larger sample, dissociative experiences during wakefulness and nightmares also showed associations. These findings offer initial insights into factors related to exploding head syndrome.
Sleep
November 16, 2023
Péter Simor, Bertalan Polner, Noémi Báthori et al.
9 citations
Mind-wandering, where attention shifts from the present to internal thoughts, is more likely after nights with less REM and N2 sleep and less intense dream experiences. Over 7 nights, 67 healthy participants wore mobile sleep EEG headbands and completed self-reports, yielding about 400 analyzable nights. Nights with more wakefulness and shorter REM and slow wave sleep were linked to poorer subjective sleep quality. Reduced REM and N2 sleep, along with less vivid dreams, predicted increased mind-wandering the following day. The findings highlight that night-to-day variations in specific sleep stages influence both perceived sleep quality and daytime mind-wandering intensity.
Sleep
February 10, 2025
Yannis Idir, Régis Lopez, Amélie Barbier et al.
5 citations
Disorders of arousal (DoA) episodes, such as sleepwalking, are not a uniform state but involve varying levels of consciousness and responsiveness. In a retrospective questionnaire, 81% of 61 adult patients reported occasional conversations during episodes. Auditory stimulation during N3 sleep triggered episodes in only 7 of 157 trials, and only one patient indirectly responded to verbal prompts. Analysis of 364 home video-recorded episodes from 19 patients found 37 instances of discussion with a bed partner. Patients' ongoing mental content influenced their responses and perception of the outside world. These findings highlight limitations in current diagnostic criteria for DoA.
Sleep
May 1, 2023
Afik Faerman, Lauren Anker, Kirsten Cherian et al.
5 citations
Ibogaine, an alkaloid used in traditional African ceremonies, may improve sleep and trauma symptoms in veterans with repeated blast exposure and traumatic brain injury. Thirty Special Operations Veterans who voluntarily underwent ibogaine treatment at a clinic outside the US completed sleep and PTSD assessments at baseline, immediately after treatment, and one month later. Sleep quality (Pittsburgh Sleep Quality Index) and insomnia severity (Pittsburgh Insomnia Rating Scale) significantly improved one month post-treatment, as did PTSD symptom severity (CAPS-5). However, the improvement in PTSD symptoms did not significantly predict the sleep improvements, suggesting ibogaine may affect sleep and trauma through different mechanisms. The findings indicate ibogaine's potential for treating disturbed sleep after traumatic brain injury.
Sleep
July 11, 2022
Claudia Picard-Deland, Max-Antoine Allaire, Tore Nielsen
5 citations
Frequent lucid dreamers show better static balance, as measured by lower center of pressure velocity on a force plate, compared to other participants, partially supporting a vestibular contribution to lucid dreaming. In a study of 131 adults who kept dream logs and performed balance tasks, lucid dreaming frequency correlated globally with better balance. Flying sensations in men's dreams and greater dream control in women's dreams were also linked to better balance. However, body height and sleepiness confounded some effects. The findings support the view that the vestibular system underlies basic aspects of bodily self-consciousness, such as self-agency and self-location, during both wakefulness and dreaming.
Sleep
January 1, 2010
Sophie Schwartz
5 citations
During the transition from wakefulness to sleep, elements from daytime activities spontaneously re-emerge in dream-like mentation called hypnagogic imagery. In a study where healthy young participants trained on a visuomotor skiing game (Alpine Racer II), 30% of spontaneous mentation collected during pre-sleep wakefulness and light NREM sleep contained imagery or thoughts related to the game. Imagery directly related to training declined across time, and game-related incorporations tended to become more abstracted. No relationship was found between introspective measures of memory replay and later performance improvement. The findings support the continuity hypothesis of dreaming and suggest novelty and motivational involvement may influence which experiences are replayed.
Sleep
May 26, 2025
Alejandra Mondino, Amir Jadidian, Brandon A Toth et al.
4 citations
The preoptic area of the hypothalamus, long thought to only promote sleep, contains glutamatergic neurons (MLPO_VGLUT2) that actually drive wakefulness and suppress REM sleep. Using fiber photometry in mice, these neurons were highly active during REM sleep, wakefulness, and brief arousals, but minimally active during non-REM sleep. Chemogenetic stimulation of MLPO_VGLUT2 inhibited REM sleep onset, independent of non-REM fragmentation caused by hypothermia, and blocked the REM sleep rebound normally seen after total sleep deprivation. Chemogenetic inhibition increased REM sleep time only during the light phase. Mapping showed these neurons project to brain regions that promote wakefulness and inhibit REM sleep. The authors conclude that MLPO_VGLUT2 powerfully suppress REM sleep, and their overactivation disrupts REM recovery.
Sleep
October 11, 2024
Jennifer M Mundt, Phyllis C Zee, Matthew D Schuiling et al.
3 citations
A remote mindfulness-based intervention adapted for narcolepsy was tested in three program lengths: brief (4 weeks), standard (8 weeks), and extended (12 weeks) among 60 adults with narcolepsy. Attendance, meditation practice, and data completeness benchmarks were met by 71.7%, 61.7%, and 78.3% of participants, respectively. All groups showed clinically meaningful improvements in mindfulness, self-compassion, self-efficacy for managing emotions, positive psychosocial impact, global mental health, and fatigue. Standard and extended groups also improved anxiety and depression; the extended group additionally improved social and cognitive functioning, daytime sleepiness, hypersomnia symptoms, and hypersomnia-related functioning. The extended program appears to offer the most clinical benefit while maintaining engagement.
Sleep
April 8, 2026
Julia Maruani, Pierre A Geoffroy
2 citations
Nightmares are strongly linked to depression and suicide risk, yet they are rarely assessed or treated in clinical practice. Up to 90% of people with major depressive episodes experience nightmares, which are among the strongest predictors of suicide attempts. Dream alterations often precede suicidal crises. Imagery rehearsal therapy (IRT), a first-line treatment for nightmare disorder, reduces nightmare frequency and emotional distress, and may also improve depressive and suicidal symptoms by reducing emotional burden, improving sleep quality, and decreasing anxiety. The authors argue that nightmares should be considered a core, modifiable risk factor for suicide and that systematic assessment and treatment of nightmares could be a valuable suicide prevention strategy.
Sleep
May 1, 2025
Robert Stickgold, Alon Shamir, Noa Brande-Eilat et al.
1 citation
A new software platform called Arctop Sleep, which uses a mobile app and an EEG headband to detect sleep onset in real time, can induce dreams on pre-selected topics and increase creativity around those topics. In pilot studies with participants experiencing PTSD, serial awakenings and dream reports were successfully recorded, with reports containing direct and metaphorical references to the chosen topic. Participants showed improvement in creativity and resilience related to the topic on post-sleep tasks compared to baseline. The platform is described as comfortable and promising for leveraging targeted dream incubation to enhance cognitive and emotional processing of trauma memories.
Sleep
May 29, 2026
Julia Maruani, Pierre A Geoffroy
Nightmares, especially in people with posttraumatic stress disorder, are linked to an increased risk of suicide. Imagery rehearsal therapy and the medication prazosin are two nightmare-focused interventions that may reduce suicide risk, but the mechanisms are not yet fully understood. The authors clarify how these treatments work—imagery rehearsal therapy by changing nightmare content and reducing distress, and prazosin by blocking adrenaline effects to lessen nightmare intensity—and propose that improving nightmare frequency and severity could lower suicidal ideation and behavior. They call for more research to directly test this connection.
Sleep
May 1, 2026
Denise C. Vidot, Bria-Necole Diggs, Amrit Baral et al.
Among daily cannabis consumers aged 18–35, about 56% reported lifetime psychedelic use, with psilocybin most common (50%), followed by LSD (29%) and DMT (3.5%). Overall, 33% had subthreshold insomnia, 3.2% moderate-severity clinical insomnia, and 1.6% severe clinical insomnia. LSD and DMT were associated with moderate-to-severe clinical insomnia: 17.7% of LSD users vs. 0.0% of non-users, and 50.0% of DMT users vs. 3.6% of non-users. Psilocybin showed no significant association. LSD users also reported more frequent sleep-related interference with daily functioning. No differences were found in cannabis use for sleep or demographics by psychedelic use.
Sleep
May 1, 2026
Hollyann Loui, Melisa Chang
A 63-year-old man with diabetes and hypertension experienced loud clapping noises while falling asleep for 25 years, occurring 5-6 times weekly. He was diagnosed with exploding head syndrome (EHS) after a polysomnogram showed moderate obstructive sleep apnea (apnea-hypopnea index of 22/hr), and a brain MRI and audiologic exam were normal. At a 6-month follow-up, episodes reduced to 1-2 times weekly without OSA treatment. EHS is an underrecognized parasomnia with lifetime prevalence of 10% to over 30%, considered benign and self-limited. No established association exists between EHS and OSA or hearing loss; EHS is most strongly associated with insomnia, sleep paralysis, and dissociative experiences.
Sleep
May 1, 2026
Holland Doise, A. Gonzalez Quesada, Garrett Baber et al.
Nightmares are linked to more severe posttraumatic stress disorder (PTSD). This study tested whether the emotional content of dreams, measured by self-report, human coding, and a large language model (LLM), could predict PTSD symptoms after a traumatic injury. 87 patients from a trauma center provided dream reports and completed surveys during hospitalization and at one and two months afterward. Dream narratives were scored by trained raters and by an LLM for negative affect and arousal. LLM-derived negative affect and arousal from dreams reported during hospitalization predicted higher PTSD symptoms one month later, even after adjusting for other risk factors. Self-reported dream affect did not predict later symptoms.
Sleep
May 1, 2026
Westley Youngren, Victoria West Staples, Emma Angle et al.
A single 90-minute session of Targeted Dream Incubation (TDI), which involves giving auditory cues to shape dream content, increased dream self-efficacy (DSE) immediately after and one week later in both a non-clinical group and a group with frequent trauma-related nightmares (TRNs). A control nap group showed no change in DSE. Only the non-nightmare TDI group showed significant reductions at one-week follow-up in thoughts of suicide, insomnia, PTSD, and nightmare distress. The results suggest TDI may reduce negative outcomes in people with TRNs, potentially through increased DSE, and justify larger-scale investigation.
Sleep
September 18, 2025
Jessica Palmieri, Deniz Kumral, Sammy-Jo Wymer et al.
Dreams incorporate specific information from waking experiences, and this incorporation may aid memory consolidation. Participants listened to an audiobook while falling asleep and were awakened during the night to report dreams. Blind raters could identify which audiobook a participant had heard based solely on dream reports, for both NREM and REM sleep dreams. Participants whose dreams more strongly incorporated the audiobook content tended to recognize more of that content later. The findings suggest that salient daytime experiences resurface in dreams and that content selected for memory consolidation during sleep is more strongly incorporated into dreams.
Sleep
May 1, 2025
Westley Youngren, Emma Angle, Victoria West Staples et al.
A brief nap-based intervention using verbal cues before sleep, called Targeted Dream Incubation (TDI), can increase people's confidence in their ability to dream (dreaming self-efficacy) and enhance the joy they feel about their dreams. In a study of 15 participants, 80% reported dreams that included the cued subject (a tree). Dreaming self-efficacy scores rose significantly from before the nap to immediately after and remained higher at a one-week follow-up. Joy related to dreams also increased significantly from baseline to the one-week follow-up. These results suggest TDI is a reliable method for boosting dreaming self-efficacy and may also positively affect emotional responses to dreaming.