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The memory sources of dreams: serial awakenings across sleep stages and time of night.

Claudia Picard-Deland, Karen R Konkoly, Rachel Raider, Ken A Paller, Tore Nielsen, Wilfred R Pigeon, Michelle Carr

Sleep April 12, 2023 DOI: 10.1093/sleep/zsac292 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Observational cohort Peer reviewed
Sample size 20
Population Healthy participants (11 female; mean age 24.1 ± 5.7 years)
Duration One night in the laboratory with approximately 12 awakenings across early, middle, and late sleep periods
Topics Dreaming
Keywords Nrem sleep Episodic memory Memory sources Semantic memory Serial awakenings Sleep stages Temporal changes
Key findings Recent memory sources were more frequent in N1 and REM dreams than in other stages, and the proportion of recent versus distant memories changed across the night independently of sleep stage, with late-night dreams containing fewer recent and more remote memories.

Abstract

Memories of waking-life events are incorporated into dreams, but their incorporation is not uniform across a night of sleep. This study aimed to elucidate ways in which such memory sources vary by sleep stage and time of night. Twenty healthy participants (11 F; 24.1 ± 5.7 years) spent a night in the laboratory and were awakened for dream collection approximately 12 times spread across early, middle, and late periods of sleep, while covering all stages of sleep (N1, N2, N3, REM). In the morning, participants identified and dated associated memories of waking-life events for each dream report, when possible. The incorporation of recent memory sources in dreams was more frequent in N1 and REM than in other sleep stages. The incorporation of distant memories from over a week ago, semantic memories not traceable to a single event, and anticipated future events remained stable throughout sleep. In contrast, the relative proportions of recent versus distant memory sources changed across the night, independently of sleep stage, with late-night dreams in all stages having relatively less recent and more remote memory sources than dreams earlier in the night. Qualitatively, dreams tended to repeat similar themes across the night and in different sleep stages. The present findings clarify the temporal course of memory incorporations in dreams, highlighting a specific connection between time of night and the temporal remoteness of memories. We discuss how dream content may, at least in part, reflect the mechanisms of sleep-dependent memory consolidation.

Comparable studies

Other observational and cohort studies on dreaming, most cited first.

Study Year Design Participants
Lucid Dreaming: a State of Consciousness with Features of Both Waking and Non-Lucid Dreaming Student volunteers trained to become lucid and signal lucidity with horizontal eye... 2009 Observational study n = 6
Nightmare Prevalence, Nightmare Distress, and Self-Reported Psychological Disturbance Young adults with a mean age of 20 years 2002 Prospective observational study n = 116
Long-term effects of extreme situational stress on sleep and dreaming Survivors of traumatic events who complained of sleep disturbances, compared with... 1987 Case-control study n = 11
The relationship of nightmare frequency and nightmare distress to well‐being Adults who reported dreams 2004 Observational cohort n = 147
Dreaming in NREM Sleep: A High-Density EEG Study of Slow Waves and Spindles Healthy human subjects 2018 Observational cohort n = 14

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