Cloé Blanchette-Carrière

Memory consolidation is associated with sleep physiology but the contribution of specific sleep stages remains controversial. To clarify the contribution of REM sleep, participants were administered two REM sleep-sensitive tasks to determine if associated changes occurred only in REM sleep. Twenty-two participants (7 men) were administered the Corsi Block Tapping and Tower of Hanoi tasks prior to and again after a night of sleep. Task improvers and non-improvers were compared for sleep structure, sleep spindles, and dream recall. Control participants (N=15) completed the tasks twice during the day without intervening sleep. Overnight Corsi Block improvement was associated with more REM sleep whereas Tower of Hanoi improvement was associated with more N2 sleep. Corsi Block improvement correlated positively with %REM sleep and Tower of Hanoi improvement with %N2 sleep. Post-hoc analyses suggest Tower of Hanoi effects-but not Corsi Block effects-are due to trait differences. Sleep spin...

Memory consolidation is associated with sleep physiology but the contributions of specific sleep stages remains controversial. To clarify the contribution of REM sleep, participants were administered two REM sleep-sensitive tasks to determine if associated changes occurred only in REM sleep. Twenty-two participants (7 men) were administered the Corsi Block Tapping and Tower of Hanoi tasks prior to and again after a night of sleep. Task improvers and non-improvers were compared for sleep structure, sleep spindles, and dream recall. Control participants (N=15) completed the tasks twice during the day without intervening sleep. Overnight Corsi Block improvement was associated with more REM sleep whereas Tower of Hanoi improvement was associated with more N2 sleep. Corsi Block improvement correlated positively with%REM sleep and Tower of Hanoi improvement with%N2 sleep. Post-hoc analyses suggest Tower of Hanoi effects-but not Corsi Block effects-are due to trait differences. Sleep spindle density was associated with Tower of Hanoi improvement whereas spindle amplitude correlated with Corsi Block improvement. Number of REM awakenings for dream reporting (but not dream recall per se) was associated with Corsi Block, but not Tower of Hanoi, improvement but was confounded with REM sleep time. This non-replication of one of 2 REM-sensitive task effects challenges both 'dual-process' and 'sequential' or 'sleep organization' models of sleep-dependent learning and points rather to capacity limitations on REM sleep. Experimental awakenings for sampling dream mentation may not perturb sleep-dependent learning effects; they may even enhance them.

Aim: Rapid eye movement (REM) sleep, non-rapid eye movement (NREM) sleep, and sleep spindles are all implicated in the consolidation of procedural memories. Relative contributions of sleep stages and sleep spindles were previously shown to depend on individual differences in task processing. However, no studies to our knowledge have focused on individual differences in experience with Vipassana meditation as related to sleep. Vipassana meditation is a form of mental training that enhances proprioceptive and somatic awareness and alters attentional style. The goal of this study was to examine a potential role for Vipassana meditation experience in sleep-dependent procedural memory consolidation. Methods: Groups of Vipassana meditation practitioners (N = 22) and matched meditation-naïve controls (N = 20) slept for a daytime nap in the laboratory. Before and after the nap they completed a procedural task on the Wii Fit balance platform. Results: Meditators performed slightly better on the task before the nap, but the two groups improved similarly after sleep. The groups showed different patterns of sleep-dependent procedural memory consolidation: in meditators, task learning was positively correlated with density of slow occipital spindles, while in controls task improvement was positively associated with time in REM sleep. Sleep efficiency and sleep architecture did not differ between groups. Meditation practitioners, however, had a lower density of occipital slow sleep spindles than controls. Conclusion: Results suggest that neuroplastic changes associated with meditation practice may alter overall sleep microarchitecture and reorganize sleep-dependent patterns of memory consolidation. The lower density of occipital spindles in meditators may mean that meditation practice compensates for some of the memory functions of sleep.

Both rapid eye movement (REM) sleep dreaming and non-rapid eye movement (NREM) sleep spindles have been linked to processes of memory consolidation. However, relationships between the two phenomena have yet to be explored. In a heterogeneous sample of 53 healthy subjects who had participated in a memory consolidation protocol and who varied in their self-reported recall of dreams and nightmares, we assessed overnight polysomno-graphy, N2 sleep spindle density, REM dream word count, and retrospective estimates of how often they recall dreams, bad dreams (dysphoric dreams, no awakening), and nightmares (dysphoric dreams, with awakenings). Fast spindle density positively correlated with all measures of dream recall but was most robustly associated with bad dream recall and REM dream word count. Correlations with bad dream recall were particularly strong for spindles occurring in sleep cycles 2 and 3 and correlations with word count for cycles 1, 4, and 5. While slow spindle density showed opposite correlations with all of these measures, partialing out slow spindles attenuated, but did not eliminate, the fast spindle correlations. Results are largely consistent with the conclusion that fast sleep spindles are associated with a common trait factor that also influences dream recall. However, the results also raise the possibility that both spindles and dreaming are expressions of memory consolidation mechanisms, such as neural replay, that transcend sleep stage.

Nightmares (NM) are characterized by intense negative emotion. Research suggests that frequent NM sufferers also have greater inclinations to fantasy and dream-like daydreams, although it is not known whether they experience intense negative emotion as part of these waking state cognitions. We assessed the daydreams and nap dreams of NM participants to determine whether they have more negative daydream content and more vivid imagery overall. NM and control (CTL) participants completed a daydream procedure followed by a nap targeted to contain 80 min total sleep time and an awakening 10 min into rapid eye movement (REM) sleep. For both daydreams and nap dreams, participants completed a questionnaire regarding 4 factors: negativity, positivity, body sensation, and bizarreness. Results revealed the NM group had elevated positivity, body sensation and bizarreness ratings for daydreams compared with the CTL group, but did not differ from them for negativity ratings. NM participants also had elevated body sensation ratings for nap dreams, but did not differ for negativity, positivity, or bizarreness. Thus, while NMs themselves are characterized by negative affect, NM sufferers nonetheless have higher than

Effect of Vipassana meditation on sleep-dependent procedural memory consolidation and postural balance following a daytime nap

E Solomonova, S Dubé, C Blanchette-Carrière, A Samson, C Picard-Deland, and T Nielsen

Numerous studies report sleep-dependent processes of memory consolidation. Procedural memory has been previously linked with rapid-eye-movement (REM) and non-REM (NREM) sleep stages, and with sleep microarchitecture (sleep spindles, rapid eye movements). Vipassana meditation is characterized by trained attention to bodily sensations: experienced meditators show better proprioceptive attunement and sensory discrimination. No study to date examined differences between meditators and non-meditating controls on sleep-dependent processes of memory consolidation.

Our objectives were to compare meditators and controls on the relationship between improvement on a full body procedural vestibular learning task, static postural balance and sleep characteristics.

42 participants (22 meditators and 20 controls) slept for a daytime nap in the laboratory. Prior to and following the nap, participants completed a vestibular proprioceptive learning task and a static balance task. They were also awakened at sleep onset and during REM sleep for dream collection.

I we will present data on sleep stages, sleep spindles and dream content. Preliminary results indicate differences between meditators and non-meditators: improvement on a procedural learning task and balance was related to the time spent in NREM Stage 2 sleep in meditators. Conversely, improvement on a learning task and balance was related to the time spent in REM sleep in control group. Results suggest that meditation practice may impact sleep-dependent processes of memory consolidation, making the “implicit” procedural learning more “explicit”.

Vipassana meditation is characterized by observing bodily sensations, developing emotional and attentional stability and promoting pro-social qualities. Whether these qualities are also reflected in dream content is not currently known. Evidence relating dream content with sleep-depending learning is mixed: some studies suggest that dreaming of a task is beneficial for improvement, while others find no such effect. This study aimed at investigating whether meditators have qualitatively different dreams than controls; whether meditators incorporate a procedural learning task more often than controls; and whether dreaming about the task is related to better post-sleep performance on the task.
20 meditators and 20 controls slept for a daytime nap at the laboratory. Prior to sleep and upon awakening they completed a procedural learning task. Dream reports were collected at sleep onset and upon awakening (REM/N2 sleep). Dreams were then scored for qualities associated with meditation practice and for incorporations of the procedural task and of the laboratory.
Meditators had longer dreams, slightly more references to the body and friendlier and more compassionate interactions with dream characters. Dreams of meditation practitioners were not more lucid than those of controls. Meditators did not incorporate the learning task or laboratory into dream content more often than controls, and no relationship was found between dream content and performance on a procedural task. In control participants, in contrast, incorporating task or laboratory in REM/N2 dreams was associated with improvement on the task, but incorporations at sleep onset were associated with slightly worse performance on the task.