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.
Keywords: Insomnia; older adults; sleep duration; sleep pattern; use of hypnotics.