Sleep, sedentary activity, physical activity, and cognitive function among older adults: The National Health and Nutrition Examination Survey, 2011–2014

Objectives We aimed to estimate the association of sleep, sedentary activity and physical activity with cognitive function among older adults, with consideration of the competing nature between variables of activity status. Design Cross-sectional study. Methods A total of 3086 older adults (60 years or older) in the 2011–2014 National Health and Nutrition Examination Survey were included. The Global Physical Activity Questionnaire was used to measure self-reported time for sedentary activity, walking/bicycling and moderate-to-vigorous physical activity (MVPA). Cognitive function was examined using the CERAD Word Learning subtest (memory), Digit Symbol Substitution Test (executive function/processing speed), and Animal Fluency Test (language). Sleep duration was obtained via interview. Isotemporal substitution models using multivariable linear regression were applied to examine the associations of replacing sleep, sedentary activity, walking/bicycling, MVPA with each other and cognitive function, stratified by sleep duration per night (≤7 h, >7 h). Results Among participants with sleep duration ≤7 h/night, replacing 30 min/day of sedentary activity with 30 min/day of MVPA or 30 min/day was associated with better cognition. Among participants with sleep duration >7 h/night, replacing 30 min/day of sleep with 30 min/day of sedentary activity, walking/bicycling, or MVPA was associated with better cognition. Conclusions Replacing sedentary activities with MVPA was associated with favorable cognitive function among older adults sleeping no longer than 7 h/night, and replacing excessive sleep with sedentary or physical activities was associated with favorable cognition. Future research is expected to examine the associations of replacing different activity status on long-term cognitive outcomes in longitudinal studies.