Longitudinal relationships between cardiovascular events, risk factors, and time-dependent sleep duration.

BACKGROUND: Although many studies have evaluated the relationships between sleep duration and cardiovascular (CV) events/risk factors, longitudinal associations with time-dependent sleep duration have not been adequately assessed.

METHODS: A retrospective, longitudinal study was conducted involving individuals aged 20 years or older that received annual health check-ups at St. Luke's International Hospital from 2005 to 2010. Data collection included self-reported demographic, clinical and health habit information (including sleep duration; < 6, 6-7, 7-8, ≥ 8 h), baseline examinations, and laboratory measures for each year. We conducted mixed effects analyses to examine the associations between non-fatal CV events, risk factors, and time-dependent sleep duration longitudinally.

RESULTS: Of the total of 31,830 participants enrolled, 70.1% of participants changed their sleep dura-tion, and 365 participants experienced CV events during follow-up periods. Compared to those reporting 7-8 h of sleep, those reporting less than 6 h of sleep were significantly more likely to experience non-fatal CV events (odds ratio [OR] 1.78; 95% confidence interval [CI] 1.03-3.07; p = 0.04), but other groups were not (OR 1.12; 95% CI 0.70-1.77; p = 0.64 for 6-7 h and OR 1.22; 95% CI 0.68-2.23; p = 0.50 for ≥ 8 h). The shortest sleep duration was associated with a higher likelihood of obesity/overweight status (OR 1.49; 95% CI 1.32-1.69; p < 0.01).

CONCLUSIONS: Individuals reporting less than 6 h of sleep were significantly more likely to have non-fatal CV events than those reporting 7-8 h of sleep. For the risk factors, short sleep duration was associ-ated with obesity/overweight status.