Excessive daytime sleepiness is related to subjective memory impairment in late life: a cross-sectional community-based study

Aim The aim of this study was to determine whether daytime sleepiness is related to subjective memory impairment among community-dwelling elderly people, after adjustment for psychosocial variables. Methods Questionnaires were mailed to all 5199 elderly residents living in one area of Tokyo. The questionnaires collected information about sociodemographic variables, subjective memory impairment, and excessive daytime sleepiness, which was measured by the Japanese version of the Epworth Sleepiness Scale. Information was also collected on sleep hygiene, health-related variables, and psychosocial variables, including perceived social support, social withdrawal, and work status. Results Of the 4783 questionnaires that were returned (92.0%), 4185 participants were included in the analysis (valid response rate: 80.5%), after the exclusion of questionnaires with missing data. The average score on the Japanese version of the Epworth Sleepiness Scale was 5.0 ± 3.9 for men and 4.5 ± 3.7 for women. The frequency of excessive daytime sleepiness was 8.3% for men, 5.8% for women, and 7.0% in total. Stepwise multivariate logistic regression revealed the odds ratio of excessive daytime sleepiness as a predictor of subjective memory impairment was 6.06 (95% confidence interval; 3.06–12.03). Conclusions Elderly people who complain of daytime sleepiness are potential candidates for interventions related to dementia care after careful consideration of other possible causes of sleepiness.