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.