Associations of sleep duration with the incidence of needed support/ long-term care certification according to presence or absence of sleep complaints in community-dwelling Japanese older adults

Background: Evidence on the variability of associations between sleep duration and incident disability according to the presence or absence of sleep complaints is limited. This study assessed the associations between sleep durations and disability incidence stratified by the presence or absence of sleep complaints. Methods: A total of 3,896 community-dwelling Japanese adults aged >65 years were observed for 37 months after the self-reporting of sleep duration and sleep complaints. Disability incidence was defined by the certification of needed support/long-term care according to the public long-term care insurance. A proportional hazards model was fitted to examine the association of sleep duration with incident disability according to the presence or absence of fatigue on awakening. Missing values of covariates were estimated using multiple imputations. Results: Long sleep duration was associated significantly with incident disability regardless of the presence or absence of fatigue on awakening; the age- and sex-adjusted hazard ratios were 1.62 (95% Confidence Interval, 1.02-2.56) and 1.35 (1.04-1.75), respectively. The elevated risks of long sleep durations without complaints disappeared after an adjustment for impairments of functional health, while that of long sleep duration with complaints disappeared after an adjustment for medical histories, especially stroke history. Conclusion: Long sleep duration was associated with disability incidence among community-dwelling older persons. The domains of health accounting for the association differed by the presence or absence of sleep complaints.