Memory for details fades over time, yet retaining the spatiotemporal associations inherent to our individual experiences may be adaptively relevant. Using an art tour as an experimental setting, Diamond, Simpson and colleagues shed light on the role of sleep in shaping the long-term retention of episodic memory for real-world events.
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For centuries, scientists have tried to understand cognitive functions such as memory by translating real life into the four walls of an experimental room. To understand the inner workings of the human mind, they break down complex cognitive functions into more simplified experimental tasks. Through these controlled studies, we have identified the subcomponents that make up our memories and uncovered distinct memory systems that enable us to recall past experiences. But our brain has evolved to operate in complex natural environments, which raises the question of whether confining human experience to artificial laboratory settings limits our access to cognitive functions. Diamond, Simpson and colleagues addressed this question by studying the effect of sleep on memory formation in the real-world context of an art tour[1](https://www.nature.com/articles/s41562-025-02130-8#ref-CR1 "Diamond, N. B. et al. Nat. Hum. Behav.
https://doi.org/10.1038/s41562-025-02117-5
(2025).").
Credit: Simon2579/DigitalVision Vectors/Getty
Episodic memory enables us to recall specific experiences, including their unique features and the place and time at which they occurred, which makes individual memories highly discriminable from each other. The brain, however, is not designed to retain the details of all of our unique experiences. Rather, it extracts invariant features, especially when we have multiple similar encounters2. Our memory for a specific event can thus change, and its ‘episodic properties’ can fade away with time. And yet, sometimes aspects of a one-time experience can stick with us: under what conditions does this occur? Past research in the laboratory has shown that sleep benefits memory consolidation3 but little is known about the role of sleep in preserving detail in episodic memory over extended periods. Except for rare cases (which mostly involve emotionally loaded stimulus material)4, memory retention for standard laboratory tasks undergoes fast decay and is thus tested shortly after learning. This makes it challenging to test memory development at longer delays.
By tailoring their research questions to fit a real-life fully immersive experience (participating in an art tour controlled by an audio guide), Diamond, Simpson and colleagues investigated what participants remembered about the experience across a period of 15 months by testing their memory one day, one week, one month and more than a year later. After completing the art tour, participants either stayed awake during the day or slept for a whole night. The researchers were interested in several unresolved questions, including whether sleep would help participants to remember individual features of the artwork or even the sequence in which they encountered the pieces and, if so, whether this benefit persists over time, as well as whether sleep passively protects the memories from decay or can actively shape which aspects are retained.
To address these questions, the authors ran three complementary studies using the ‘Baycrest Tour’, an audio guide that walked participants through different artworks in the Baycrest Centre in Toronto and instructed them to closely inspect each item and focus on its characteristics. Later, participants were probed on individual characteristics of each item (featural memory) as well as the temporal order in which they encountered the different art pieces (sequential memory), two distinct dimensions of episodic memory. The results of these studies showed that a period of sleep after learning, as compared with staying awake, improved participants’ sequential memory at the expense of featural memory of the individual artworks. This effect persisted over time — surprisingly, for up to 15 months after the one-shot learning experience. By investigating how the brain naturally stores information as participants walked through an art tour, the authors demonstrate that sleep not only makes a difference for our memories, but also shapes which content is retained in the long term.
This raises questions of what the advantage of retaining memory for a sequence of events instead of memory for details might be, and why sleep is particularly beneficial for this. It is noteworthy that in most of our real-world experiences, we move forwards across time and space simultaneously. In contrast to laboratory environments, in real life these two contextual dimensions are necessarily correlated and cannot be disentangled5. Exploring a novel environment usually activates the hippocampus, a brain structure that is involved in the processing of space and time, in forming associations, and, particularly, in binding memory to its spatial and temporal context. Place cells (that is, cells that track an individual’s location in space) and time cells (which fire at temporally defined moments during an experience) are key to this function. Interestingly, place cells that are active while exploring an environment become reactivated during later sleep6. This reactivation is often sequential, and recapitulates neural activity during learning (so-called replay)7. During sleep, memory replay occurs mostly in the forward direction8. Thus, the improved memory for the temporal order of the art tour may stem from this property of sleep-dependent memory reactivation. Notably, Diamond, Simpson and colleagues found a significant positive association between overnight memory retention and the coupling of sleep spindles with slow oscillations. This temporal coordination of oscillatory activity has previously been linked to successful memory reactivation9.
In the study by Diamond, Simpson and colleagues, it remains unclear which strategy participants used to retrieve the sequential aspects of their experience: whether they relied solely on the temporal succession of the items or used the spatial route that connects one artwork to another. It is likely that their approach involved a combination of both. The strong benefit of sleep observed in this paradigm might thus result from the cumulative contribution of two interacting systems (a system that processes space and a system that processes time) that overall provide a spatiotemporal map of the experience. This organizational structure of the experience facilitates later retrieval of the event, which assigns it a high adaptive value. Consolidation during sleep may therefore prioritize this information.
Importantly, replay might not be the only form in which memories are reactivated10. In some cases, the neural ensembles that were active during learning might instead be globally reinstated, in a simultaneous fashion: would such a global reinstatement — contrary to replay — strengthen the featural aspects of memories? In a sequence of fortunate events (pun intended), sleep research has entered the field. The study by Diamond, Simpson and colleagues has paved the way for ecological designs to investigate which aspects of episodic memory are particularly susceptible to sleep after learning. Focusing on human behaviour in natural environments will complement existing research on memory functions, which has so far largely remained constrained to laboratory settings.
References
Diamond, N. B. et al. Nat. Hum. Behav.https://doi.org/10.1038/s41562-025-02117-5 (2025).
ArticleGoogle Scholar
Cowan, E. T., Schapiro, A. C., Dunsmoor, J. E. & Murty, V. P. Psychon. Bull. Rev. 28, 1796–1810 (2021).
ArticlePubMedGoogle Scholar
Diekelmann, S. & Born, J. Nat. Rev. Neurosci. 11, 114–126 (2010).
ArticleCASPubMedGoogle Scholar
Dolcos, F., LaBar, K. S. & Cabeza, R. Proc. Natl Acad. Sci. USA 102, 2626–2631 (2005).
ArticleCASPubMedPubMed CentralGoogle Scholar
Nastase, S. A., Goldstein, A. & Hasson, U. Neuroimage 222, 117254 (2020).
ArticlePubMedGoogle Scholar
Wilson, M. A. & McNaughton, B. L. Science 265, 676–679 (1994).
ArticleCASPubMedGoogle Scholar
Ji, D. & Wilson, M. A. Nat. Neurosci. 10, 100–107 (2007).
ArticleCASPubMedGoogle Scholar
Carr, M. F., Jadhav, S. P. & Frank, L. M. Nat. Neurosci. 14, 147–153 (2011).
ArticleCASPubMedPubMed CentralGoogle Scholar
Maingret, N., Girardeau, G., Todorova, R., Goutierre, M. & Zugaro, M. Nat. Neurosci. 19, 959–964 (2016).
ArticleCASPubMedGoogle Scholar
Huang, Q. et al. Nat. Commun. 15, 7185 (2024).
ArticleCASPubMedPubMed CentralGoogle Scholar
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Institute of Psychology, Neuropsychology, University of Freiburg, Freiburg, Germany
Jessica Palmieri & Monika Schönauer
BrainLinks BrainTools, University of Freiburg, Freiburg, Germany
Monika Schönauer
Bernstein Center Freiburg, Freiburg, Germany
Monika Schönauer
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Palmieri, J., Schönauer, M. Sleep studies enter the real world. Nat Hum Behav (2025). https://doi.org/10.1038/s41562-025-02130-8
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Published:11 March 2025
DOI:https://doi.org/10.1038/s41562-025-02130-8
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