Sleep duration and mortality according to health status in older adults

Abstract

Objectives: To examine the association between usual sleep duration and mortality according to physical and mental health status in older adults.

Design: Prospective study conducted from 2001 to 2008.

Setting: Community-based study.

Participants: Cohort study of 3,820 persons representative of the noninstitutionalized population aged 60 and older in Spain.

Measurements: Sleep duration was self-reported at baseline. Analyses were performed using Cox regression and adjusted for the main confounders. The analyses were then stratified according to numerous indicators of health status.

Results: During follow-up, 897 persons died. Mortality was higher in those who slept 8 hours (relative risk (RR)=1.34, 95% confidence interval (CI)=1.02-1.76), 9 hours (RR 1.48, 95% CI=1.12-1.96), 10 hours (RR 1.73, 95% CI=1.30-2.29) and 11 hours or more (RR 1.66, 95% CI=1.23-2.24) than in those who slept 7 hours (P for trend <.001). The association between long sleep duration (≥10 vs 7 hours) and mortality was observed even in persons with good health status: optimal perceived health, good cognitive function (Mini-Mental State Examination score >27), no depression, quality of life better than the cohort median (Medical Outcomes Study 36-item Short Form Survey Physical Component Summary score ≥46 and Mental Component Summary score ≥52), and without disability in instrumental activities of daily living. Sleeping 6 hours or less was not associated with higher mortality than sleeping 7 hours in persons with good health status.

Conclusion: Self-reported sleep duration was associated with 7-year mortality in this cohort of older adults, even when adjusted for health status. Further research is needed to determine the mechanisms and clinical implications of these findings.