Sex- and age-specific all-cause mortality in insomnia with hypnotics: Findings from Japan multi-institutional Collaborative Cohort Study

Objective: Findings on the increased mortality risk in individuals with insomnia are inconsistent across studies. Rather than improving insomnia by sleep control, hypnotic use may be one factor in the increased risk of death; however, the effects of hypnotics on mortality remains unclear. This study aimed to examine the association between all-cause mortality and hypnotic use in a large sample, while adjusting for the effects of comorbidities. Methods: Overall, 92,527 individuals aged 35–69 years were followed up for mortality in the Japan Multi-Institutional Collaborative Cohort Study. Regular use of hypnotics was assessed using a self-administered questionnaire. Since cancer history carries a substantial risk of death and is associated with the treatment of insomnia with hypnotics, participants with a cancer history were excluded. The hazard ratio (HR) and 95% confidence interval (CI) for all-cause mortality related to hypnotic use were estimated using a Cox proportional hazard model with adjustments for covariates including sleeping hours and comorbidities (body mass index, ischemic heart disease, stroke, and diabetes). Results: During the follow-up (mean, 8.4 ± 2.5 years), 1,492 mortalities were recorded, and the prevalence of taking hypnotics was 4.2%. Hypnotic use was associated with significantly greater risk of all-cause mortality, even after adjustment for the covariates (HR, 1.32; 95% CI, 1.07–1.63). The association between hypnotic use and all-cause mortality was robust in males (HR, 1.51; 95% CI, 1.15–1.96), and participants aged <60 years (HR, 1.75; 95% CI, 1.21–2.54). Conclusions: Our study revealed sex-age specific associations between hypnotic use and all-cause mortality.