A Nine-Year Follow-up Study of Sleep Patterns and Mortality in Community-Dwelling Older Adults in Taiwan

Study Objectives: To simultaneously explore the associations between mortality and insomnia, sleep duration, and the use of hypnotics in older adults. Design: A fixed cohort study. Setting: A community in Shih-Pai area, Taipei, Taiwan. Participants: A total of 4,064 participants over the age of 65 completed the study. Intervention: N/A. Measurements and Results: Insomnia was classified using an exclusionary hierarchical algorithm, which categorized insomnia as "no insomnia," "subjective poor sleep quality," "Pittsburgh Sleep Quality Index > 5 insomnia," "1-month insomnia disorder," and "6-month insomnia disorder." The main outcome variables were 9-year all-cause mortality rates. In the all-cause mortality analyses, when hypnotic use, depressive symptoms and total sleep time were excluded from a proportional hazards regression model, subjects with "Pittsburgh Sleep Quality Index > 5 insomnia" had a higher mortality risk (HR: 1.21, 95% CI: 1.01-1.45). In the full model, frequent hypnotic use and long sleep duration predicted higher mortality rates. However, the increased mortality risk for subjects with " Pittsburgh Sleep Quality Index > 5 insomnia" was not observed in the full model. On the contrary, individuals with a 6-month DSM-IV insomnia disorder had a lower risk for premature death (HR: 0.64, 95% CI: 0.43-0.96). Conclusions: Long sleep duration and frequent hypnotics use predicted an increased mortality risk within a community-dwelling sample of older adults. The association between insomnia and mortality was affected by insomnia definition and other parameters related to sleep patterns.