PLoS One
October 11, 2017
Raphael Vallat, Benoit Chatard, Mark Blagrove et al.
60 citations
Over seven days, 40 participants recorded their dreams and identified related waking-life elements (WLEs), including remote and trivial memories. On average, 83.4% of dream reports linked to at least one WLE. Among dated WLEs, 40.2% occurred the day before the dream, 26.1% in the prior month, 15.8% in the prior year, and 17.9% more than a year earlier. While most incorporated WLEs were rated as important, those from the day before were mostly mundane, consistent with Freud's day residues. Both positive and negative WLEs were rated as emotionally less intense in dreams than in waking, supporting the emotional regulation hypothesis of dreaming.
Scientific Reports
October 30, 2019
Jane Plailly, Manon Villalba, Raphael Vallat et al.
42 citations
Whether dream content reflects memory consolidation is an open question. After reviewing the literature, an experiment tested if incorporating recently learned material into dreams relates to better memory after sleep. Thirty-two high dream recallers freely explored new visuo-olfactory episodes for 3 consecutive days. During subsequent nights, they woke at 5am and their usual waking time to record dreams; 120 dreams were reported. Elements from the encoding phase appeared in 37 dreams, mostly visual rather than olfactory. On day 4, participants with learning-related dreams showed similar odor recognition and odor-evoked episodic memory as others, but significantly better visuo-spatial memory of the episodes. Results suggest the learning phase is loosely incorporated into dreams and this incorporation is associated with sleep-related memory consolidation.
Frontiers in Psychology
November 15, 2019
Raphael Vallat, Perrine Marie Ruby
32 citations
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Cerebral cortex (New York, N.Y. : 1991)
August 22, 2022
Perrine Ruby, Rémy Masson, Benoit Chatard et al.
People who frequently recall their dreams show larger brain responses to unexpected sounds, even when actively paying attention to a task, indicating enhanced bottom-up processing of irrelevant auditory stimuli. They also exhibit larger brain signals related to expecting and responding to target sounds, suggesting greater top-down attention recruitment. Despite these differences, their behavioral performance on attention tasks is not impaired, though it may come at a higher cognitive cost. The findings propose that in high dream recallers, increased bottom-up processing may facilitate dream recall by promoting awakening during sleep, while enhanced top-down processes may support dream recall through greater awareness or short-term memory stability of dream content.
Nature and Science of Sleep
January 1, 2022
Raphael Vallat, Başak Türker, Alain Nicolas et al.
People who frequently recall their dreams show greater functional connectivity in the default mode network (DMN) during resting wakefulness and score higher on creativity tests than those who rarely recall dreams. No significant difference in memory abilities appeared between the groups. However, creativity scores did not correlate significantly with DMN connectivity. These findings support the idea that dreaming and mind wandering are related spontaneous mental processes linked to the DMN, and suggest that increased DMN activity may promote creative thinking during both wakefulness and sleep, though causal evidence remains to be established.
Sleep
December 14, 2020
Raphael Vallat, Alain Nicolas, Perrine Ruby
People who frequently recall dreams show distinct brain connectivity patterns immediately after waking compared to those who rarely recall dreams. The study measured brain functional connectivity using combined EEG-fMRI in 20 high dream recallers and 18 low dream recallers before and after an early-afternoon nap. Five minutes after awakening, high recallers exhibited enhanced connectivity within the default mode network and between the default mode network and memory-related brain regions. This connectivity pattern may help maintain the short-term memory of dreams during the transition from sleep to wakefulness. The groups differed in dream recall but not in recall of a comic presented before the nap.
Journal of Sleep Research
October 1, 2018
Raphael Vallat, Mickael Eskinazi, Alain Nicolas et al.
French college students spend about 8 hours in bed on weekdays and 9 hours on weekends, with 90.9% reporting no difficulty falling asleep. Dream recall averages about 3 mornings per week, positively linked to dream clarity and lucid dreaming frequency, and negatively linked to age. Nearly 7% report regular sleep-talking, while less than 0.4% have regular sleepwalking. Frequent lucid dreams occur in 14% of students, and recurrent dreams in 6%. Women report higher dream recall and more time in bed than men. Humanities students spend more time in bed than science students, suggesting a link between academic discipline and sleep duration.
Frontiers in Psychology
January 1, 2018
Raphael Vallat, Jean-Baptiste Eichenlaub, Alain Nicolas et al.
People who frequently recall dreams have denser white matter in the medial prefrontal cortex (MPFC) than those who rarely recall dreams. Using brain scans of 46 high dream recallers (who recalled dreams about six mornings per week) and 46 low dream recallers (who recalled dreams less than once per week), researchers found no differences in gray or white matter density in the temporo-parietal junction, hippocampus, or amygdala. The finding aligns with evidence that damage to MPFC white matter can stop dream reporting, suggesting this region plays a role in dream recall or production.
Frontiers in Human Neuroscience
January 1, 2017
Raphael Vallat, Tarek Lajnef, Jean-Baptiste Eichenlaub et al.
People who frequently recall their dreams show larger brain responses to sounds while awake and asleep and spend more time awake during the night, but their overall sleep structure is similar to that of low dream recallers. In a study of 18 high and 18 low dream recallers, sounds were played during a full night of sleep while brain activity was recorded. No differences in sleep microstructure—such as arousals, eye movements, or muscle twitches—were found between the groups. High recallers had more stimuli that caused awakenings and longer awakenings, but not more frequent or longer arousals.
Arna Ghosh, Arthur Dehgan, Tarek Lajnef et al.
People who often remember their dreams and those who rarely do show different brain activity patterns during sleep. Using deep convolutional networks on full-night EEG recordings from 36 subjects (18 high dream recall, 18 low dream recall), the authors trained separate classifiers for each sleep stage to predict which group a person belonged to. The classification accuracies revealed which sleep stages contain the best neural predictors of dream recall rate. A subject discriminator network was added as an adversary to ensure the model learned group-discriminating features rather than subject-specific ones. These features were visualized with a cue-combination Class Activation Map method. The findings are compared with prior studies, and future research directions are discussed.