Sleep complaints and incident disability in a community-based cohort study of older persons.

OBJECTIVE: Sleep complaints are associated with adverse health consequences. We hypothesized that non-disabled older persons with more sleep complaints have an increased risk of developing disability.

METHODS: Subjects included 908 older clergy participating in the Religious Order Study without clinical dementia, history of stroke, or Parkinson disease. At baseline, participants rated their difficulty falling asleep, frequency of nocturnal awakenings, sleep efficacy, and napping frequency, from which a summary dyssomnia measure was derived. Self-report assessment of disability included instrumental activities of daily living (IADLs), basic activities of daily living (ADLs), and Rosow-Breslau mobility disability at baseline and at annual evaluations.

RESULTS: Mean follow-up was 9.6 (SD: 4.2) years. At baseline, more than 60% had one or more sleep complaints. In a series of Cox proportional hazards models controlling for age, sex, and education, a one-point higher dyssomnia score at baseline was associated with about 20% increased risk of IADL disability (hazard ratio: 1.20; 95% confidence interval [CI]: 1.04-1.39; χ(2)1 = 7.62; p <0.05), about 27% increased risk of ADL disability (hazard ratio: 1.27; 95% CI: 1.10-1.47; χ(2)1 = 12.15; p <0.01), and about 27% increased risk of mobility disability (hazard ratio: 1.27; 95% CI: 1.09-1.48; χ(2)1 = 11.04; p <0.01). These associations did not vary by age, sex, or education and remained significant after controlling for potential confounders including body mass index, chronic medical conditions, and several common medications. Controlling for depressive symptoms attenuated the association between sleep complaints and incident IADL and ADL disabilities but the association between sleep complaints and incident mobility disability remained significant.

CONCLUSION: Non-disabled older adults with more sleep complaints have an increased risk of developing disability.