Factors of nocturnal sleep and daytime nap durations in community-dwelling elderly: a longitudinal population-based study.

Abstract

Durations of nocturnal sleep and daytime nap influence the well-being of older adults. It is thus essential to understand their determinants. However, much previous research did not assess sleep duration and nap duration individually, and longitudinal data is lacking. This study aimed at examining the impact of demographic, psychosocial, and health factors, including ethnicity, social networks outside the household, smoking and physical exercise on sleep duration and nap duration among community-dwelling elderly. Our study involved over 2,600 older adults (≥60 years) from a longitudinal, nationally representative survey - the Panel on Health and Ageing of Singaporean Elderly. Sleep and nap durations at Time 2 (two years later) were regressed on predictors measured at Time 1. Time 2 short nocturnal sleep duration was predicted by Malay ethnicity (relative to Chinese and Indian), older age, lower education level, more depressive symptoms, and obesity, whereas future long nocturnal sleep duration was predicted by weaker social networks, older age, and more chronic diseases. Furthermore, smoking, obesity, Malay or Indian (relative to Chinese), older age, male gender, and cognitive impairment predicted longer daytime nap duration in the future. Older adults' nocturnal sleep and daytime nap durations may be affected by different demographic, psychosocial, and health factors. Thus, it is important to differentiate these two attributes in this age group.