Napping characteristics and cognitive performance in older adults

Objectives To determine the association of napping intention, frequency, and duration with cognition in a nationally-representative sample of US older adults. Methods We performed a cross-sectional analysis of community-dwelling Medicare beneficiaries aged >= 65 years from Rounds 3 or 4 (2013-2014) of the National Health and Aging Trends Study (N = 2549). Participants reported past-month napping intention (intentional/unintentional), napping frequency (rarely/never [non-nappers], some days [infrequent nappers], most days/every day [frequent nappers]), and average nap duration (we categorized as <= 30 minutes [short]; 31-60 minutes [moderate]; and > 60 minutes [long]). Cognitive outcomes were performance on immediate and delayed word recall tests (IWR and DWR, respectively), the Clock Drawing Test (CDT), and self-rated memory (score: 1[excellent]-5[very poor]). Results After adjustment for potential confounders, unintentional nappers had poorer immediate word recall test performance than non-nappers (B = -0.23, P < 0.01) and intentional nappers (B = -0.26, P < 0.01). After further adjustment for daytime sleepiness, frequent nappers reported poorer self-rated memory than non-nappers (B = 0.14, P < 0.05). Compared with short nappers, long nappers had poorer IWR (B = -0.26, P < 0.05) and CDT scores (B = -0.17, P < 0.05). Except for the association of nap duration with IWR and CDT, these associations remained after excluding participants with dementia and/or proxy respondents. Among participants undiagnosed with dementia or proxies, moderate-duration naps were associated with better DWR than short naps (B = 0.24, P < 0.05). Neither napping intentionality nor frequency was associated with CDT performance. Conclusions Among older adults, distinct aspects of napping are associated with cognitive performance. Prospective research, with objective measures of napping, is needed to elucidate the link between napping and cognitive trajectories.