Journal of Sleep Research
January 29, 2019
Annika Gieselmann, Malik Ait Aoudia, Michelle Carr et al.
192 citations
Chronic nightmares arise from an interaction between elevated hyperarousal and impaired fear extinction, facilitated by trait affect distress from traumatic experiences, early childhood adversity, trait susceptibility, elevated thought suppression, and potentially sleep-disordered breathing. Treatment options target nightmare meaning, chronic repetition, or maladaptive beliefs. The paper reviews epidemiological findings, aetiology models for traumatized and non-traumatized individuals, and evidence-based interventions, noting gaps in healthcare provider knowledge and delivery. Future perspectives for nightmare treatment and aetiology research are outlined.
Neuroscience of Consciousness
January 1, 2017
Tore Nielsen
57 citations
Sleep onset normally happens quickly and without notice, but in the lab it reveals how waking, perceptually grounded consciousness shifts into the hallucinatory simulations of dreaming. This review focuses on imagery during the sleep-onset transition—especially "microdreams"—as an alternative to studying dreaming in the traditional sleep lab. Preliminary work on microdream phenomenology has helped classify dreaming's core features (the "oneiragogic spectrum"), assess multiple memory inputs ("multi-temporal memory sources"), identify two new imagery types ("autosensory imagery" and "exosensory imagery"), and embed microdreaming in a "multisensory integration approach." These efforts may clarify dream neurophysiology and dreaming's role in memory consolidation, and advance the neuroscience of consciousness.
PLoS One
October 6, 2021
Claudia Picard-Deland, Tore Nielsen, Michelle Carr
27 citations
Over a third of dreams collected in a sleep laboratory incorporate elements of the lab itself, such as experimenters, electrodes, or the setting. These lab incorporations are especially common during REM sleep (44.2%) and morning naps (48.4%). They tend to be associated with higher depression scores but not with sex, nightmare-proneness, or anxiety. Common themes include meta-dreaming (lucid dreams and false awakenings, 40.7%), sensory incorporations (27%), wayfinding (24.3%), sleep as performance (19.6%), friends or family in the lab (15.9%), and being an object of observation (12.2%). Nearly a third of these dreams projected the dreamer into the near future, while very few projected into the past.
Consciousness and Cognition
August 1, 2020
Claudia Picard-Deland, Maude Pastor, Elizaveta Solomonova et al.
25 citations
Flying dreams, though common, rarely occur. In a study with 137 participants, a virtual reality flying task followed by a morning nap increased reports of flying dreams during the nap and the following morning, compared to baseline rates and a control group. These dreams also showed greater lucid control and emotional intensity. Prior dream-flying experience and the level of VR sensory immersion influenced induction. The results support a vection-based explanation of dream-flying and could aid in developing dream flight-induction technologies.
Consciousness and Cognition
August 1, 2020
Cloé Blanchette-Carrière, Sarah-Hélène Julien, Claudia Picard-Deland et al.
20 citations
The neurophysiological basis of self-awareness during sleep (lucid dreaming) is still poorly understood. Previous work suggested that transcranial alternating current stimulation (tACS) during sleep could increase dream self-awareness, but methodological flaws in those studies motivated a new investigation. In the current study, both tACS and a sham procedure were associated with signal-verified and self-rated lucid dreams, indicating that situational factors, rather than the stimulation itself, may be critical for inducing self-awareness during sleep.
Frontiers in Human Neuroscience
May 23, 2014
Elizaveta Solomonova, Kieran C. R. Fox, Tore Nielsen
17 citations
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Front Psychol
January 23, 2020
Elizaveta Solomonova, Simon Dubé, Cloé Blanchette-Carrière et al.
9 citations
Vipassana meditation practitioners show different patterns of how sleep consolidates procedural memories compared to non-meditators. The study compared overnight memory retention in meditators and controls, finding that meditators exhibited distinct consolidation processes, suggesting that long-term meditation practice alters sleep-dependent memory processing.
Frontiers in Neuroscience
March 18, 2021
Louis-Philippe Marquis, Sarah-Hélène Julien, Véronique Daneault et al.
6 citations
Frequent nightmares are linked to altered brain activity in regions beyond the limbic-prefrontal circuit, including frontal, parietal, temporal, occipital, and subcortical areas. A resting-state fMRI study compared 18 frequent nightmare recallers aged 18–35 with matched controls. Nightmare recallers showed greater regional homogeneity in the left anterior cingulate cortex and right inferior parietal lobule. Positive correlation emerged between retrospective nightmare frequency and hippocampal regional homogeneity. Results suggest multiple brain regions contribute to nightmare formation, partially supporting a neurocognitive model involving medial prefrontal and anterior cingulate cortices, hippocampus, and amygdala.
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.
Frontiers in Psychology
July 1, 2025
Tore Nielsen, Jade Radke, Claudia Picard-Deland et al.
3 citations
A survey of 1,082 people found that 40.2% reported certain foods worsened or improved their sleep, and 5.5% said food affected their dreams. Desserts/sweets (31%) and dairy (22%) were most often blamed for dream changes. Perceived food effects on dreams linked to higher nightmare recall and Nightmare Disorder Index scores, and were associated with food allergies and gluten intolerance. Worse sleep perceptions tied to lactose intolerance, with gastrointestinal symptoms mediating the link to nightmares. Healthy eating habits like less evening eating predicted higher dream recall, while unhealthy eating predicted nightmares and dream negativity. The findings suggest dairy-induced gastrointestinal symptoms may underlie some bizarre or disturbing dreams.
Oxford Handbooks Online
April 5, 2018
Tore Nielsen
1 citation
The fleeting dream images of sleep onset, called microdreams, are briefer and simpler than REM dreams and more accessible to study. Examining their phenomenology has helped develop a classification system for dreaming's core features (Windt's oneiragic spectrum), establish a structure for assessing dreaming's multiple memory inputs, uncover two new types of imagery (autosensory and exosensory), and provide a framework for explaining microdreaming processes through multisensory integration. Continued focus on microdream neurophenomenology may help resolve questions about dreaming's core features, brain correlates, and memory sources.
Trends in Cognitive Sciences
December 1, 2024
Remington Mallett, Karen R Konkoly, Tore Nielsen et al.
A review of recent interdisciplinary advances that overcome historical methodological barriers in dream research. Three frameworks are described: observable dreaming, using neural decoding and real-time reporting to measure dream content more directly; dream engineering, using targeted stimulation and lucidity to experimentally manipulate dream content; and computational dream analysis, generating and exploring large dream-report databases to identify patterns. These innovations enable systematic observation, engineering, and analysis of dreams, heralding a new era in dream science.
Sleep
April 12, 2023
Claudia Picard-Deland, Karen R Konkoly, Rachel Raider et al.
Dreams incorporate memories from waking life, but this incorporation varies across the night. Twenty healthy adults were awakened repeatedly during early, middle, and late sleep stages (N1, N2, N3, REM) to collect dream reports. Recent memories appeared more often in N1 and REM dreams than in other stages. Distant memories from over a week ago, semantic memories, and anticipated future events remained stable across sleep stages. However, across the night, the balance shifted: late-night dreams in all stages contained fewer recent and more remote memories than earlier dreams. Dreams also repeated similar themes across the night. These results suggest that dream content may reflect sleep-dependent memory consolidation processes.
Journal of Sleep Research
February 1, 2022
Claudia Picard-Deland, Tore Nielsen
Auditory cues played during specific sleep stages can shift the timing of when a newly learned virtual reality flying task reappears in dreams. Cues presented during REM sleep led to more task-related dreams 1-2 days later, while cues presented during slow-wave sleep led to more such dreams 5-6 days later, compared to no cueing. This delayed effect helps explain the day-residue effect (dreams about new learning the next day) and the dream-lag effect (dreams about new learning 5-7 days later), suggesting that memory reactivation during sleep influences the temporal pattern of dream content.
Neurobiology of Learning and Memory
September 1, 2021
Claudia Picard-Deland, Tomy Aumont, Arnaud Samson-Richer et al.
Applying targeted memory reactivation (TMR) during REM sleep improves learning of a whole-body procedural task more than TMR applied during slow-wave sleep, wake, or no reactivation. Dreams that incorporate kinesthetic elements of the task, such as flying or accelerating, are associated with greater performance gains than dreams with visual elements or no task-related content. TMR does not directly alter dream content, but its performance benefits are larger when task-related dream reactivations also occur in REM sleep. These results suggest that dream imagery may reflect memory reactivation processes that support skill consolidation during sleep.
Journal of Sleep Research
December 1, 2019
Julie A E Christensen, Sébrina Aubin, Tore Nielsen et al.
Rapid eye movements (EMs) during REM sleep are not necessary for visual dream imagery. Blind individuals, both congenitally blind and late blind, showed significantly less eye movement coverage during wakefulness and all sleep stages compared to sighted controls. Late blind subjects reported more visual dream elements than congenitally blind subjects, yet both blind groups had similarly low eye movement activity. The near absence of nocturnal eye movements in late blind subjects, despite preserved visual dream content, does not support the hypothesis that REM sleep eye movements reflect visual scanning of dream imagery. Results indicate a dissociation between eye movements and visual dream content in blind individuals.
Sleep Medicine
October 1, 2018
Claudia Picard-Deland, Michelle Carr, Tyna Paquette et al.
Frequent nightmare recallers show abnormalities in non-REM (NREM) sleep, specifically in sleep spindles—brain oscillations linked to memory consolidation and psychopathology. Compared to controls, the nightmare group had lower density of slow spindles across most EEG sites, higher density of fast spindles in frontal regions, and elevated fast spindle frequency in central regions. These differences remained after controlling for depression. Correlational analyses revealed that higher psychopathology scores were associated with higher slow spindle densities and slower spindle frequencies only in the nightmare group.
Trends in Cognitive Sciences
December 1, 2016
Jennifer Windt, Tore Nielsen, Evan Thompson
The assumption that consciousness disappears during deep, dreamless sleep is oversimplified. Empirical and theoretical reasons indicate that a range of different types of sleep experience, some distinct from dreaming, can occur in all sleep stages. A novel taxonomy for describing these dreamless sleep experiences is introduced, along with research methods for their investigation. Future studies should focus on memory consolidation, sleep disorders, and sleep state (mis)perception. This proposal suggests new directions for sleep and dream science, the neuroscience of consciousness, and can inform the diagnosis and treatment of sleep disorders.
Journal of Sleep Research
August 1, 2015
Gaëlle Dumel, Michelle Carr, Louis-Philippe Marquis et al.
People who habitually recall few dreams performed worse on a visuomotor task (mirror tracing) before sleep but showed greater overnight improvement than those who recall many dreams. The improvement in low recallers was linked to Stage 2 sleep rather than rapid eye movement sleep. The findings suggest that dreaming relates to visuomotor processes and that different levels of visuomotor skill engage distinct sleep-related consolidation mechanisms.
Sleep Medicine
June 1, 2014
Jessica Lara-Carrasco, Valérie Simard, Kadia Saint-Onge et al.
In late pregnancy, women experience more bad dreams and nightmares than non-pregnant women, even though overall dream recall is similar between the two groups. Among 57 third-trimester pregnant women and 59 non-pregnant controls, 21% of pregnant women reported nightmare frequency exceeding moderately severe pathology (more than one per week), compared to 7% of non-pregnant women. Pregnant women also reported lower sleep quality and more night awakenings. Higher recall of bad dreams and nightmares correlated with lower sleep quality in the pregnant group. The findings suggest that increased dysphoric dream imagery may contribute to impaired sleep during late pregnancy.
Frontiers in Neurology
January 1, 2012
Tore Nielsen
Dream recall frequency peaks in early adulthood (ages 20-29) and then declines over the next 20 years, with different patterns for males and females. Males show a gradual decline starting in their 30s, reaching a low point in their 40s, while females experience a later, more abrupt decline starting in their 40s and reaching a low in their 50s. Sex differences in recall are most pronounced between ages 14 and 44. Dream theme diversity decreases linearly with age for both sexes up to ages 50-59, then drops more sharply for those aged 60-79, with a sex difference favoring males only during adolescence (ages 10-19). These patterns parallel age-related changes in sleep structure, particularly decreasing REM sleep, as well as declines in episodic and autobiographical memory.
Sleep
December 1, 2009
Tore Nielsen, Connie Svob, Don Kuiken
Dream-enacting behaviors—such as speaking, crying, smiling, and moving during sleep—are common in healthy young adults, with prevalence rising from 36% to 98% depending on how specifically questions are asked. Women report more speaking, crying, fear, and smiling or laughing during dreams, while men report more sexual arousal. These gender differences persist even after accounting for other sleep disorders and dream recall. The behaviors are largely independent of other parasomnias like sleepwalking or nightmares, except for dream-talking, which is linked to sleep-talking. They are not related to alexithymia but are moderately tied to absorption. Social desirability does not affect reporting.
Psychotherapy (Chicago, Ill.)
December 1, 2009
Valérie Simard, Tore Nielsen
A psychotherapeutic treatment for nightmares, adapted from imagery rehearsal therapy for 6- to 11-year-old children, was tested with ten child-mother dyads over three sessions and eight weeks. Participation, which included contact with a clinician and keeping a prospective dream log, was associated with decreases in unpleasant dreams frequency, nightmare distress, and manifest anxiety. Providing educational information about nightmares contributed to this positive effect. Drawing modified versions of nightmares for one month was associated with further reductions in nightmare distress and anxiety but not with changes in unpleasant dreams frequency. Follow-ups at three and six months posttreatment suggest maintained effects.
Elizaveta Solomonova, Simon Dubé, Arnaud Samson-Richer et al.
Meditators have longer dreams with friendlier, more compassionate interactions and slightly more references to the body, but their dreams are no more lucid than those of non-meditators. Meditators did not incorporate a procedural learning task or the laboratory into their dreams more often than controls. Among control participants, incorporating the task or laboratory into REM/N2 dreams was linked to improved task performance, while incorporations at sleep onset were tied to slightly worse performance. No relationship between dream content and procedural task performance was found for meditators.
Elizaveta Solomonova, Simon Dubé, Cloé Blanchette-Carrière et al.
Meditation experience alters how sleep supports memory consolidation. In a study of Vipassana meditation practitioners and meditation-naïve controls who napped in a laboratory, both groups improved similarly on a balance task after sleep, but the brain activity underlying that improvement differed. In meditators, task learning was linked to slow occipital sleep spindles and negatively linked to fast spindles, whereas in controls improvement was associated with increased REM sleep. Meditators also had fewer sleep spindles overall, especially in occipital regions. The findings suggest that long-term meditation practice may reorganize sleep-dependent memory processes and compensate for some memory functions of sleep.