Risk of napping: excessive daytime sleepiness and mortality in an older community population.

OBJECTIVE: To describe the demographic and health-related factors related to excessive daytime sleepiness. To estimate the risk of mortality associated with excessive daytime sleepiness independent of nightime sleep problems and other factors that limit survival.
DESIGN: Four-year prospective cohort study with annual interviews.
SETTING: One urban and four rural counties in north-central North Carolina. PARTICIPANTS: Adults 65 years and older (n = 3962) living in the community. MAIN OUTCOME MEASURES: Excessive daytime sleepiness was measured as, "How often do you get so sleepy during the day or evening that you have to take a nap?" Mortality was based on continuous surveillance of the population by field investigators and abstraction of death certificates.
RESULTS: Point prevalence of excessive daytime sleepiness in this population was 25.2%. Frequent daytime nappers were more likely than infrequent nappers to report nighttime sleep complaints and were more likely to be male and urban-dwellers, to report more depressive symptoms, more limited physical activity, and more functional impairment, and were more likely to be overweight. Of the frequent nappers, 23.9% died, compared with 15.4% of infrequent nappers. In an adjusted Cox proportional hazard model, the 4-year mortality rate was accelerated 1.73 times among older people who nap most of the time and make two or more errors on a cognitive status examination.
CONCLUSION: Excessive napping is associated with impaired sleep hygiene as well as with a broad range of activity-related health deficits among community-dwelling older adults. Frequent napping was associated with impaired sleep hygiene, male gender, urban-dwelling, depressive symptoms, physical activity deficits, functional impairment, and excess weight. Mortality risk was elevated selectively among the most cognitively impaired subjects.