The Impact of Sleep on Face Recognition Memory: A Scoping Review.

Sleep has a major impact on a variety of human biological and cognitive functions. In particular, its impact on memory has attracted extensive research and has been amply demonstrated. However, it is still unclear whether sleep, or lack thereof, affects the ability to recognize faces. To clarify this, we conducted a scoping review on studies that included a face recognition memory task and any kind of sleep manipulation in adults without any sleep pathology. A systematic search and synthesis of peer-reviewed journal articles identified through the electronic databases Scopus, Web of Science, EBSCO, and PubMed was performed. A final sample of 18 articles, corresponding to 19 studies, met the eligibility criteria. The results of 13 articles suggested that sleep benefited face recognition ability, whereas two articles indicated a detrimental effect of sleep on performance, and four articles found no significant effects. This review highlights the high methodological variability between studies, in terms of sleep manipulation, retention interval, tasks used to probe face recognition, and other variables. In sum, although around one third of the studies show a beneficial effect of sleep on memory for faces, we suggest that future research should invest in replicating these findings with a stricter control of potentially confounding variables to allow stronger conclusions to be drawn.