Impact of sleep habits on life expectancy free of cardiovascular disease in the Chinese population: a prospective cohort study.

BACKGROUND: Abnormal sleep duration and poor sleep quality have been associated with increased risks of cardiovascular disease (CVD) incidence and mortality. However, little is known about how these sleep problems affect total life expectancy (LE) and LE free of CVD and its subtypes. METHODS: We included 483,384 adults from the China Kadoorie Biobank (CKB) who were free of heart disease, stroke, cancer, major depressive disorder, and generalized anxiety disorder at baseline. Sleep duration was categorized as < 6 h/d, 6-9 h/d, and >9 h/d. Three sleep disturbance symptoms were considered: self-reported difficulties initiating and maintaining sleep, early morning awakening, and daytime dysfunction. Participants with at least one of the three symptoms were considered to have a sleep disturbance. We estimated sex-specific LE with and without CVD at age 40 by using multistate Markov models, with separate models specified for total CVD, ischemic heart disease (IHD), ischemic stroke (IS), and hemorrhagic stroke (HS) as the disease state. RESULTS: During a median follow-up of 12.1 years, we documented 135,429 incident CVD events, including 46,479 IHD events, 47,562 IS events, and 10,844 HS events. Overall, there were 48,372 deaths. Compared to other sleep problems, longer sleep duration (>9 h/d) had the greatest impact on total LE and LE free of CVD and its subtypes, with the impact on total LE greater than that of disease-free LE. In men, the reduction in total LE and LE without CVD (95% confidence intervals) at age 40 associated with longer sleep duration was 2.11 (-2.50, -1.71) and 1.29 (-1.68, -0.98) years, respectively. The corresponding values for women were 1.37 (-1.81, -0.98) and 0.43 (-0.75, -0.07) years. In contrast, sleep disturbance had a stronger impact on disease-free LE than on total LE, thereby reducing the proportion of life spent in a healthy state. Compared with participants without sleep disturbance, the total LE at age 40 was 0.46 (-0.77, -0.15) and 0.22 (-0.47, 0.06) years lower in men and women with sleep disturbance, respectively, and the LE without CVD was 0.99 (-1.23, -0.73) and 1.05 (-1.27, -0.85) years lower. CONCLUSIONS: In this Chinese population, abnormal sleep duration, especially long sleep, and sleep disturbance were linked with lower total LE and LE free of CVD. This study confirmed the importance of good sleep habits in health management for both those without and with CVD.