Which Domains of Cognition in Older Adults Are Affected by Sleep Duration? A Scoping Review.

Background: Over the past decade, research on the impact of sleep duration on cognitive domains in older adults has been emerging; however, a formal synthesis of the focused literature that addresses all cognitive domains has not yet been conducted. Therefore, this review study was conducted to investigate the effects of sleep duration on various cognitive domains in older adults. Methods: This scoping review was conducted according to Arksey and O'Malley (2005). A systematic search was conducted across three research databases: PubMed, Web of Science, and Scopus, with relevant gray literature also reviewed. Studies that reported on the relationship between sleep duration and cognition among older adults were included in the review. Data were extracted, charted, and synthesized into a narrative. Consistent with the purpose of a scoping review, the methodological quality of the studies was not appraised. Results: A total of 23 studies published between 2009 and 2024 fulfilled the inclusion criteria. The findings revealed that both excessively long and short sleep durations were strongly linked to impairments in learning, memory, and complex attention. Only a limited number of studies explored all cognitive domains, with none addressing social cognition. Additionally, analyses considering gender differences were notably absent. Conclusion: This review highlights cognitive domains affected by inadequate sleep in older adults and emphasizes the need for more research on gender-specific differences in sleep duration. It also pointed out a gap in understanding the link between sleep duration and social cognition, emphasizing the need for further studies in this area.