Sleep disturbances and mortality: Results from the Canadian study of health and aging

OBJECTIVES: To cross-validate, in a secondary analysis, the observation that daytime sleepiness is associated with an increased risk of death. DESIGN: Prospective cohort study. SETTING: Canada, a nationally representative sample of people age 65 and older. PARTICIPANTS: Nine thousand and eight community-dwelling participants in the Canadian Study of Health and Aging. MEASUREMENTS: Exposures: self-reported sleep disturbances. Outcomes: Cox hazard ratios (HRs) for death. RESULTS: The unadjusted analysis showed a small increased risk of death from daytime sleepiness (HR = 1.89; 95% confidence interval (CI) = 1.44-2.46), but this finding did not persist in a multivariate model adjusted for age, depression, cognition, comorbid illness, and function. CONCLUSION: Daytime sleepiness itself is not associated with an increased risk of death when other factors are taken into account. Daytime sleepiness may be a proxy for other morbid conditions and therefore for overall tiredness.