Irregular sleep and all-cause mortality: A large prospective cohort study

Objectives: Previous studies using objective parameters have shown that irregular sleep is associated with the disease incidence, progression, or mortality. This study aimed to determine the association between subjec-tive sleep duration and sleep regularity, with mortality in a large population.Methods: Participants were from the Japan Multi-Institutional Collaborative Cohort study. We obtained infor-mation from each participant on sleep duration, sleep regularity, and demographics and overall lifestyle using self-administered questionnaires. We defined sleep regularity according to participants' subjective assessment of sleep/wake time regularity. Participants (n = 81,382, mean age: 58.1 +/- 9.1years, males: 44.2%) were classified into 6 groups according to sleep duration and sleep regularity. Hazard ratios (HR) for time-to -event of death were calculated using the Cox proportional hazards model.Results: The mean follow-up period was 9.1 years and the mean sleep duration was 6.6 h/day. Irregular sleep significantly increased the risk of all-cause mortality in all models compared with regular sleep (HR 1.30, 95% confidence interval; CI, 1.18-1.44), regardless of sleep duration. Multivariable analysis of the 6 groups by sleep pattern (sleep regularity and duration) showed irregular sleep and sleep durations of <6 h/day, 6 to <8 h/day, or >= 8 h/day were associated with a 1.2-1.5-fold increases in mortality, compared to regular sleep and sleep duration of 6 to <8 h/day.Conclusions: Our study shows an association between sleep irregularity and all-cause mortality in a large Jap-anese population. Our findings provide further confirmation of the need to consider not only sleep duration, but also the regularity aspect of sleep schedules.(c) 2022 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.

Automated summary

This study investigates the association between subjective sleep duration and sleep regularity with mortality. The results show that irregular sleep is associated with an increased risk of all-cause mortality, regardless of sleep duration.