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Bloxham A, Horton CL. Enhancing and advancing the understanding and study of dreaming and memory consolidation: Reflections, challenges, theoretical clarity, and methodological considerations. Conscious Cogn 2024; 123:103719. [PMID: 38941924 DOI: 10.1016/j.concog.2024.103719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 04/24/2024] [Accepted: 06/12/2024] [Indexed: 06/30/2024]
Abstract
Empirical investigations that search for a link between dreaming and sleep-dependent memory consolidation have focused on testing for an association between dreaming of what was learned, and improved memory performance for learned material. Empirical support for this is mixed, perhaps owing to the inherent challenges presented by the nature of dreams, and methodological inconsistencies. The purpose of this paper is to address critically prevalent assumptions and practices, with the aim of clarifying and enhancing research on this topic, chiefly by providing a theoretical synthesis of existing models and evidence. Also, it recommends the method of Targeted Memory Reactivation (TMR) as a means for investigating if dream content can be linked to specific cued activations. Other recommendations to enhance research practice and enquiry on this subject are also provided, focusing on the HOW and WHY we search for memory sources in dreams, and what purpose (if any) they might serve.
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Affiliation(s)
- Anthony Bloxham
- Nottingham Trent University, Nottingham, NG1 4FQ, United Kingdom.
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Diushekeeva A, Hidalgo S, Zadra A. Impact of Pre-Sleep Visual Media Exposure on Dreams: A Scoping Review. Brain Sci 2024; 14:662. [PMID: 39061403 PMCID: PMC11274468 DOI: 10.3390/brainsci14070662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 06/24/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024] Open
Abstract
A body of experimental research has aimed to investigate processes underlying dream formation by examining the effects of a range of pre-sleep stimuli and events on subsequent dream content. Given its ever-growing presence and salience in people's everyday lives, pre-sleep media consumption stands out as a key variable that could influence people's dreams. We conducted a scoping review to evaluate the experimental evidence of the effects of pre-sleep exposure to visual media on dream content. A systematic search on PubMed, PsycInfo, and Web of Science using terms related to moving visual media and dreams yielded 29 studies meeting the inclusion criteria. Overall, we found modest yet varied effects of pre-sleep exposure to visual media on dream content, with rates of stimulus-related incorporation ranging from 3% to 43% for REM dream reports, 4% to 30% for NREM sleep mentation reports, and between 11% and 35% for home dream reports. Our review highlights the large methodological heterogeneity and gaps across studies, the general difficulty in influencing dream content using pre-sleep exposure to visual media, and suggests promising venues for future research to advance our understanding of how and why digital media may impact people's dreams.
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Affiliation(s)
- Ajar Diushekeeva
- Department of Psychology, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada;
| | - Santiago Hidalgo
- Department of Art History and Cinematographic Studies, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada;
| | - Antonio Zadra
- Department of Psychology, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada;
- Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM—Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Blvd Ouest, Montréal, QC H4J 1C5, Canada
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Tononi G, Boly M, Cirelli C. Consciousness and sleep. Neuron 2024; 112:1568-1594. [PMID: 38697113 PMCID: PMC11105109 DOI: 10.1016/j.neuron.2024.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/04/2024] [Accepted: 04/10/2024] [Indexed: 05/04/2024]
Abstract
Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be regained, in all its richness, when we are disconnected from the environment and unable to reflect. By considering the neurophysiological differences between dreaming and dreamless sleep, we can learn about the substrate of consciousness and understand why it vanishes. We also learn that the ongoing state of the substrate of consciousness determines the way each experience feels regardless of how it is triggered-endogenously or exogenously. Dreaming consciousness is also a window on sleep and its functions. Dreams tell us that the sleeping brain is remarkably lively, recombining intrinsic activation patterns from a vast repertoire, freed from the requirements of ongoing behavior and cognitive control.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
| | - Melanie Boly
- Department of Neurology, University of Wisconsin, Madison, WI 53719, USA
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA
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Zhang J, Pena A, Delano N, Sattari N, Shuster AE, Baker FC, Simon K, Mednick SC. Evidence of an active role of dreaming in emotional memory processing shows that we dream to forget. Sci Rep 2024; 14:8722. [PMID: 38622204 PMCID: PMC11018802 DOI: 10.1038/s41598-024-58170-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 03/25/2024] [Indexed: 04/17/2024] Open
Abstract
Dreaming is a universal human behavior that has inspired searches for meaning across many disciplines including art, psychology, religion, and politics, yet its function remains poorly understood. Given the suggested role of sleep in emotional memory processing, we investigated whether reported overnight dreaming and dream content are associated with sleep-dependent changes in emotional memory and reactivity, and whether dreaming plays an active or passive role. Participants completed an emotional picture task before and after a full night of sleep and they recorded the presence and content of their dreams upon waking in the morning. The results replicated the emotional memory trade-off (negative images maintained at the cost of neutral memories), but only in those who reported dreaming (Dream-Recallers), and not in Non-Dream-Recallers. Results also replicated sleep-dependent reductions in emotional reactivity, but only in Dream-Recallers, not in Non-Dream-Recallers. Additionally, the more positive the dream report, the more positive the next-day emotional reactivity is compared to the night before. These findings implicate an active role for dreaming in overnight emotional memory processing and suggest a mechanistic framework whereby dreaming may enhance salient emotional experiences via the forgetting of less relevant information.
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Lacaux C, Strauss M, Bekinschtein TA, Oudiette D. Embracing sleep-onset complexity. Trends Neurosci 2024; 47:273-288. [PMID: 38519370 DOI: 10.1016/j.tins.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 01/17/2024] [Accepted: 02/07/2024] [Indexed: 03/24/2024]
Abstract
Sleep is crucial for many vital functions and has been extensively studied. By contrast, the sleep-onset period (SOP), often portrayed as a mere prelude to sleep, has been largely overlooked and remains poorly characterized. Recent findings, however, have reignited interest in this transitional period and have shed light on its neural mechanisms, cognitive dynamics, and clinical implications. This review synthesizes the existing knowledge about the SOP in humans. We first examine the current definition of the SOP and its limits, and consider the dynamic and complex electrophysiological changes that accompany the descent to sleep. We then describe the interplay between internal and external processing during the wake-to-sleep transition. Finally, we discuss the putative cognitive benefits of the SOP and identify novel directions to better diagnose sleep-onset disorders.
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Affiliation(s)
- Célia Lacaux
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland; Institut du Cerveau (Paris Brain Institute), Institut du Cerveau et de la Moelle Épinière (ICM), Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Paris 75013, France.
| | - Mélanie Strauss
- Neuropsychology and Functional Neuroimaging Research Group (UR2NF), Center for Research in Cognition and Neurosciences (CRCN), Université Libre de Bruxelles, B-1050 Brussels, Belgium; Departments of Neurology, Psychiatry, and Sleep Medicine, Hôpital Universitaire de Bruxelles, Site Erasme, Université Libre de Bruxelles, B-1070 Brussels, Belgium
| | - Tristan A Bekinschtein
- Cambridge Consciousness and Cognition Laboratory, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK
| | - Delphine Oudiette
- Institut du Cerveau (Paris Brain Institute), Institut du Cerveau et de la Moelle Épinière (ICM), Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Paris 75013, France; Assistance Publique - Hopitaux de Paris (AP-HP), Hôpital Pitié-Salpêtrière, Service des Pathologies du Sommeil, National Reference Centre for Narcolepsy, Paris 75013, France.
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Ataei S, Dresler M, Schoch SF. The prospects of open science practices and large-scale collaborations for dream research. Sleep 2023; 46:zsad139. [PMID: 37170861 PMCID: PMC10710988 DOI: 10.1093/sleep/zsad139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 05/13/2023] Open
Affiliation(s)
- Somayeh Ataei
- Institute of Cognitive Neuroscience, Ruhr University Bochum, Bochum, Germany
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Martin Dresler
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sarah F Schoch
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Center of Competence Sleep and Health Zurich, University of Zurich, Zurich, Switzerland
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Ataei S, Simo E, Bergers M, Schoch SF, Axmacher N, Dresler M. Learning during sleep in humans - A historical review. Sleep Med Rev 2023; 72:101852. [PMID: 37778137 DOI: 10.1016/j.smrv.2023.101852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/04/2023] [Accepted: 09/13/2023] [Indexed: 10/03/2023]
Abstract
Sleep helps to consolidate previously acquired memories. Whether new information such as languages and other useful skills can also be learned during sleep has been debated for over a century, however, the sporadic studies' different objectives and varied methodologies make it difficult to draw definitive conclusions. This review provides a comprehensive overview of the history of sleep learning research conducted in humans, from its empirical beginnings in the 1940s to the present day. Synthesizing the findings from 51 research papers, we show that several studies support the notion that simpler forms of learning, such as habituation and conditioning, are possible during sleep. In contrast, the findings for more complex, applied learning (e.g., learning a new language during sleep) are more divergent. While there is often an indication of processing and learning during sleep when looking at neural markers, behavioral evidence for the transfer of new knowledge to wake remains inconclusive. We close by critically examining the limitations and assumptions that have contributed to the discrepancies in the literature and highlight promising new directions in the field.
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Affiliation(s)
- Somayeh Ataei
- Department of Neuropsychology, Faculty of Psychology, Ruhr University Bochum, Bochum, Germany; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Eni Simo
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Mathijs Bergers
- Department of Psychiatry, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Sarah F Schoch
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands; Center of Competence Sleep & Health Zurich, University of Zurich, Zurich, CH, Switzerland
| | - Nikolai Axmacher
- Department of Neuropsychology, Faculty of Psychology, Ruhr University Bochum, Bochum, Germany
| | - Martin Dresler
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands.
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Konkoly KR, Picard-Deland C, Morris D, Mallett R. Dreaming outside the Box: Evidence for Memory Abstraction in REM Sleep. J Neurosci 2023; 43:6952-6953. [PMID: 37852785 PMCID: PMC10586531 DOI: 10.1523/jneurosci.1374-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/05/2023] [Accepted: 08/13/2023] [Indexed: 10/20/2023] Open
Affiliation(s)
- Karen R Konkoly
- Department of Psychology, Northwestern University, Evanston, Illinois 60208
| | - Claudia Picard-Deland
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, H4J 1C5, Canada
- Department of Psychiatry and Addictology, Université de Montréal, Montreal, Quebec, H3T 1J4, Canada
| | - Daniel Morris
- Department of Psychology, Northwestern University, Evanston, Illinois 60208
| | - Remington Mallett
- Department of Psychology, Northwestern University, Evanston, Illinois 60208
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