Rest-activity rhythm and cognitive function in older adults: A scoping review and integrative framework

•Rest-activity rhythm encompasses sleep, activity, and rest across a 24-hour cycle and may impact cognitive aging over time.•The relationship between rest-activity rhythm and cognitive functions, such as memory and executive function, varies significantly across studies.•Methodological differences across studies impact the findings on rest-activity rhythm's association with cognitive function, emphasizing the need for standardized approaches in future research. Rest-activity rhythm (RAR) encompasses sleep, activity, and rest across a 24-hour cycle and over time (i.e., peak activity timing, mean activity level, activity amplitude, and rhythmicity). While the link between sleep, exercise, and cognitive function is established, the specific relationship between RAR and cognitive function in older adults remains unclear. This review synthesizes the literature on RAR and cognition, identifying 26 eligible studies from databases including PubMed, CINAHL, PsycINFO, and Web of Science. Although it was difficult to draw definitive conclusions due to the limited number of available studies focusing on each of cognitive domain and methodological heterogeneity among them, the collective findings broadly indicate that later peak activity timing, higher mean activity levels, higher activity amplitude, and more stable rhythmicity were associated with better global cognition. Future research with larger, diverse samples, more accurate RAR and cognition measurements, and incorporating biomarkers will provide deeper insights into these relationships.