Sleep Duration and Mortality: A Prospective Study of 113,138 Middle-Aged and Elderly Chinese Men and Women

Objectives: To evaluate associations of sleep duration with total mortality and disease-specific mortality in a Chinese population. Design: Prospective study conducted from 1996 (for women)/2002 (for men) to 2010. Setting: A population-based cohort study in Shanghai, China. Intervention: None. Measurements and Results: A total of 113,138 participants (68,548 women and 44,590 men) of the Shanghai Women's and Men's Health Studies, aged 44-79 y and 40-75 y (women and men, respectively) at sleep duration assessment, were included in the study. In-person interviews were conducted to collect information on sleep duration, socioeconomic status, living conditions, history of chronic disease, participation in regular exercise, and family history of disease. The cohort has been followed using a combination of biannual in-person interviews and record linkages with Shanghai's population-based death registry. Survival status of participants on December 31, 2010 was included as the study outcome. Relative risks were calculated using a Cox proportional model stratified by sex and comorbidity score. There were 4,277 deaths (2,356 among women; 1,921 among men) during a median follow-up time of 7.12 y for women and 6.07 y for men. Among both women and men, sleep duration showed a J-shaped association with total mortality. Hazard ratios (95% confidence intervals) were 1.15 (1.01-1.32), 1.06 (0.94-1.20), 1.17 (1.04-1.32), 1.36 (1.13-1.64), and 2.11 (1.77-2.52) for women and 1.06 (0.90-1.25), 1.07 (0.94-1.23), 1.13 (1.00-1.28), 1.34 (1.10-1.62), and 1.55 (1.29-1.86) for men who slept 4-5, 6, 8, 9, and >= 10 h per day, respectively, compared with those who slept 7 h per day. Associations for disease-specific mortality, including cardiovascular disease, stroke, diabetes, and cancer, also generally followed the same J-shaped pattern. The sleep duration-mortality association was more evident among participants with comorbidities, but varied little by sex. Conclusion: In our study population of Chinese adults, shorter and longer sleep durations were independently associated with increased risk of mortality. But longer sleep duration had a higher mortality risk of cardiovascular disease and diabetes than short sleep.