The influential claim that sleep consolidates memories selectively — preferentially strengthening emotionally salient (especially negative) and future-relevant material over neutral or irrelevant material — is foundational to theories of sleep function, yet its evidential status is contested. A large replication with over 250 participants, conducted explicitly in response to the power criticism, supports selectivity for negative emotional objects (Denis et al. 2022), while a meta-analysis of sleep/wake contrasts finds no overall emotional selectivity (Schäfer et al. 2020), a critical review concludes that the majority of studies do not support selectivity (Davidson et al. 2021), the future-relevance effect has failed direct replication (Ashton & Cairney 2021), and severe publication bias has been demonstrated in the adjacent motor-sequence sleep-consolidation literature (Rickard et al. 2022). As of August 2026 the problem remains open: whether selectivity of sleep-dependent consolidation is real, an artifact of underpowering and selective reporting of positive results, or dependent on as-yet-unmapped moderators is unresolved, and no bias-corrected synthesis of the selectivity literature exists. The key selectivity paradigms have not been re-tested at the power and pre-registration standard that the criticism demands, and the existing literature has not been re-synthesized with explicit publication-bias correction.

Background

Memory consolidation is the post-learning stabilization of newly encoded memories. Sleep-dependent consolidation refers to the observation that material is retained better when the retention interval contains sleep than when it contains an equivalent period of wakefulness. Beyond this general benefit, an influential line of research claims that consolidation during sleep is selective: sleep does not strengthen all memories equally, but preferentially stabilizes material tagged as important. Two families of selectivity claims dominate the literature. The first concerns emotional salience: memory for the emotional components of an episode (for example a negative object) is claimed to be preserved over a night of sleep while memory for the neutral background context decays, a finding established with the emotional-scenes paradigm of Payne, Stickgold, Swanberg and Kensinger (2008), and closely tied to the hypothesis that rapid eye movement (REM) sleep — the dream-rich sleep stage — preferentially processes emotional material. The second concerns future relevance: memories that the sleeper expects to need later, operationalized by informing participants that they will be retested, are claimed to be selectively strengthened during sleep, as reported by Wilhelm, Diekelmann, Molzow, Ayoub, Mölle and Born (2011); such findings are often described as sleep reading priority tags assigned at encoding. Slow-wave sleep (SWS), the deep sleep stage dominated by large slow cortical oscillations, is the other principal stage implicated in consolidation.

The evidential foundation of these claims has come under sustained criticism. Cordi and Rasch (2021) documented replication failures, null findings, and boundary conditions across the sleep-memory literature and called for replication studies and higher reproducibility standards. Siegel (2021) argued that memory consolidation is largely similar in quiet wakefulness and sleep and that studies supporting a special role of sleep have major methodological problems. Davidson, Jönsson, Carlsson and Pace-Schott (2021), whose critical review of this literature had first circulated as a 2020 preprint, systematically reviewed the selectivity literature and concluded that although some studies support selectivity based on emotion or other cues of future relevance, the majority of studies do not, and that no sleep physiological variable has been reliably found to be specifically associated with consolidating one kind of memory over another. A meta-analysis of sleep and emotional recognition memory by Schäfer, Wirth, Staginnus, Becker, Michael and Sopp (2020), covering 1059 post-sleep/post-wake observations, found that the retention advantage for emotional over neutral material was not significantly larger after sleep than after wake in sleep/wake designs, and when wake-group parameters were estimated for studies lacking wake controls the emotional advantage was significantly larger in wake groups. Ashton and Cairney (2021) failed to replicate the future-relevance (test-expectancy) effect of Wilhelm et al. (2011) in two online experiments. Rickard, Pan and Gupta (2022), using precision-effect-test (PET) and PET-with-standard-errors (PEESE) regression — regression-based diagnostics that relate published effect sizes to their standard errors to estimate the distortion from publication bias — showed that the adjacent motor-sequence sleep-consolidation literature contains severe publication bias, strong enough that its apparent overnight gains are plausibly illusory.

Against this skeptical background, Denis, Sanders, Kensinger and Payne (2022), in a study with over 250 participants explicitly designed to answer the power criticism, found that sleep selectively benefits memory for negative emotional objects at the expense of their paired neutral backgrounds, while a second large experiment found no such sleep modulation for positive objects. The literature therefore contains a direct and unresolved conflict: large new experiments support one form of emotional selectivity (negative material), whereas the aggregated older literature does not, and the possibility that the positive literature is inflated by publication bias and underpowering — documented for a neighboring paradigm — has never been quantified by a bias-corrected synthesis of the selectivity literature itself. Reviews and empirical studies through 2025 continue to describe sleep-emotional memory findings as inconsistent, and no comprehensive bias-corrected meta-analysis of the selectivity question has appeared.

Problem Statement

Determine the true evidential status of the claim that sleep-dependent consolidation is selective — that sleep preferentially strengthens emotionally salient (especially negative) and future-relevant memories over neutral or irrelevant material, rather than consolidating memories uniformly. Adjudicate among three hypotheses: (i) selectivity is a real, replicable property of sleep-dependent consolidation; (ii) the apparent selectivity in the published literature is an artifact of underpowered studies and selective reporting of positive results; or (iii) selectivity is real but conditional on moderators that the existing literature has not mapped (for example valence and arousal of the material, paradigm type, sleep-stage involvement, population, and design features). The resolution of this question turns on evidence from well-powered, pre-registered replications of the key selectivity paradigms — the negative-emotional-object scene paradigm and the future-relevance/test-expectancy paradigm, with sleep/wake comparisons — and on a bias-corrected synthesis of the existing selectivity literature that makes its publication-bias diagnostics explicit. The answer must state, with quantified uncertainty, which specific selectivity claims survive (for example negative-object selectivity, future-relevance tagging, or REM-specific emotional consolidation) and under what conditions they hold, or conclude that the apparent effects are consistent with underpowering and publication bias.

References

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