Cited by 74Sleep and Wakefulness ResearchMemory Processes and InfluencesSleep and related disorders

The sleep benefit in episodic memory: An integrative review and a meta-analysis.

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Berres, Sabrina, Erdfelder, Edgar·2021·Psychological Bulletin

Abstract

People recall more information after sleep than after an equally long period of wakefulness. This sleep benefit in episodic memory has been documented in almost a century of research. However, an integrative review of hypothesized underlying processes, a comprehensive quantification of the benefit, and a systematic investigation of potential moderators has been missing so far. Here, we address these issues by analyzing 823 effect sizes from 271 independent samples that were reported in 177 articles published between 1967 and 2019. Using multilevel metaregressions with robust variance estimates, we found a moderate overall sleep benefit in episodic memory (g = 0.44). Moderator analyses revealed four important findings: First, the sleep benefit is larger when stimuli are studied multiple times instead of just once. Second, for word materials, the effect size depends on the retrieval procedure: It is largest in free recall, followed by cued recall and recognition tasks. Third, the sleep benefit is stronger in pre-post difference measures of retention than in delayed memory tests. Fourth, sleep benefits are larger for natural sleep and nighttime naps than for alternative sleep study designs (e.g., slow-wave sleep; SWS-deprived sleep, daytime naps). Although there was no obvious evidence for selective reporting, it is a potential threat to the validity of the results. When accounting for selective reporting bias, the overall effect of sleep on episodic memory is reduced but still significant (g = 0.28). We argue that our results support an integrative, multicausal theoretical account of sleep-induced episodic memory benefits and provide guidance to increase their replicability. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

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  • In healthy younger adults, sleep compared with wakefulness consistently improves declarative memory consolidation.

    “In healthy younger adults, sleep compared with wakefulness consistently improves declarative [14], episodic [14], emotional [26], prospective [24], and motor memory consolidation [28].”

    From Sleep and memory consolidation in healthy, neurotypical children, and adults: a summary of systematic reviews and meta-analyses. (2023) · cites this paper as [14]

    The Selection Criteria and age analysis (Parity Check Variables; page not given) support a sleep-versus-wake benefit for episodic memory in healthy adults, with most included studies involving young adults. But the Study Selection section says the meta-analysis specifically assessed episodic memory and excluded semantic-memory tasks. It therefore does not establish the claim for declarative memory broadly, and its average benefit does not mean improvement in every comparison. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • Sleep has larger effects for emotional stimuli and direct retention measures.

    “This review utilised multilevel meta-regression models to analyse a broad range of studies, revealing larger effects for emotional stimuli and direct retention measures.”

    From Sleep and memory consolidation in healthy, neurotypical children, and adults: a summary of systematic reviews and meta-analyses. (2023) · cites this paper as [14]

    The Statistical Analysis section describes a multilevel meta-analysis, and Parity Check Variables reports a significantly larger sleep benefit for direct retention measures than for delayed-test performance. Focal Variables reports a descriptively larger benefit for negative than for positive or neutral memories, but says the difference was not statistically significant. The claim presents that emotional-stimulus pattern more definitively than the paper does. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • In healthy younger adults, sleep compared with wakefulness consistently improves episodic memory consolidation.

    “In healthy younger adults, sleep compared with wakefulness consistently improves declarative [14], episodic [14], emotional [26], prospective [24], and motor memory consolidation [28].”
  • Declarative memory consolidation correlates with hippocampal activation patterns.

    “Analyses indicate SWS [23] and sleep spindles [23] facilitate declarative memory consolidation, which correlates with hippocampal activation patterns [14].”
  • Sleep promotes memory consolidation across domains including declarative, episodic, emotional, prospective, and motor memory.

    “Overall, while there is evidence that sleep promotes memory consolidation across domains including declarative, episodic, emotional, prospective, and motor memory [14]”

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Cites

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Research works printed but not linked: 18

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Authors
Berres, S., & Erdfelder, E.
Affiliations
University of Mannheim (DE)
Venue
Psychological Bulletin
Published
2021-12
Volume
147
Issue
12
Pages
1309-1353
ISSN
  • 0033-2909 (ISSN-L)
  • 1939-1455
OpenAlex
W4225863305
Cited by
74
References
354
Citations by year
2026: 11 · 2025: 17 · 2024: 24 · 2023: 18 · 2022: 4
FWCI
6.02
Type
journal article
Language
en
Open access
Locations
  • Psychological Bulletin (publishedVersion)
  • PubMed (publishedVersion)
  • PsyArXiv (OSF Preprints) (submittedVersion)
  • MADOC (University of Mannheim) (submittedVersion)
Funders
Deutsche Forschungsgemeinschaft (GRK 2277)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Sleep and Wakefulness Research
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Memory Processes and Influences
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and related disorders
Keywords
sleep-dependent memory consolidation, episodic memory, memory retention, free recall, cued recall, recognition memory, word learning, selective reporting, replicability
MeSH terms
Humans, Mental Recall, Sleep, Wakefulness, Polysomnography, Memory, Episodic

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