Short sleep duration as an independent predictor of cardiovascular events in Japanese patients with hypertension

Background: It is not known whether short duration of sleep is a predictor of future cardiovascular events in patients with hypertension. Methods: To test the hypothesis that short duration of sleep is independently associated with incident cardiovascular diseases (CVD), we performed ambulatory blood pressure (BP) monitoring in 1255 subjects with hypertension (mean [SD] age, 70.4 [9.9] years) and followed them for a mean period of 50 (23) months. Short sleep duration was defined as less than 7.5 hours (20th percentile). Multivariable Cox hazard models predictingCVD events were used to estimate the adjusted hazard ratio and 95% confidence interval (CI) for short sleep duration. A riser pattern was defined when mean nighttime systolic BP exceeded daytime systolic BP. The end point was a cardiovascular event: stroke, fatal or nonfatal myocardial infarction (MI), and sudden cardiac death. Results: In multivariable analyses, short duration of sleep (<7.5 hours) was associated with incident CVD (hazard ratio [HR], 1.68; 95% CI, 1.06-2.66; P=.03). A synergistic interaction was observed between short sleep duration and the riser pattern (P=.09). When subjects were classified according to their sleep time and a riser vs nonriser pattern, the group with shorter sleep durationplus the riser pattern had a substantially and significantly higher incidence of CVD than the group with predominant normal sleep durationplusthe nonriser pattern (HR, 4.43; 95% CI, 2.09-9.39; P<.001), independent of covariates. Conclusions: Short duration of sleep is associated with incident CVD risk and the combination of the riser pattern and short duration of sleep that is most strongly predictive of future CVD, independent of ambulatory BP levels. Physicians should inquire about sleep duration in the risk assessment of patients with hypertension.