Self-reported sleep duration and coronary heart disease mortality: A large cohort study of 400,000 Taiwanese adults

BACKGROUND: Most previous studies on sleep duration and coronary heart disease (CHD) have been small and have inadequately controlled for cardiovascular risk factors and chronic diseases. Therefore, our aim was to prospectively examine the associations of sleep duration with CHD while accounting for these factors.

METHODS: Prospective cohort study of 392 164 adults at age 20years or older who attended a health check-up program from 1994 to 2011 in Taiwan and who have information on sleep duration, sleep medications and potential confounders. Participants answered the question: "How long do you sleep for?"-there were four response categories: (a) 0-4h; (b) 4-6h; (c) 6-8h and (d) >8h. The participants were then followed for CHD mortality from the Taiwanese cause-of-death register.

RESULTS: When compared to those who slept 6-8h per night, the risk of dying from CHD was increased by 34% (HR 1.34, 95% Confidence Interval [CI] 0.87-2.07) and 35% (HR 1.35, 95% CI 1.11-1.65) in those who slept less than 4h per night and more than 8h per night, respectively. When stratifying by sex and age, we found some evidence for a stronger U-shaped association in females than in males and in older adults than in younger adults (p for interaction=0.01 and 0.13, respectively).

CONCLUSIONS: Adequate sleep duration should be considered an important component of a healthy lifestyle. Further studies are needed to better elucidate the underlying mechanisms.