Sleep complaints predict coronary artery disease mortality in males: a 12-year follow-up study of a middle-aged Swedish population

Objectives. Only a few prospective surveys have been performed to investigate the relationship between sleep complaints and coronary artery disease (CAD) mortality. This study was conducted to determine whether sleep complaints in a middle-aged population predicted total mortality and CAD mortality. Design. A population-based prospective study. Setting. The County of Dalarna, Sweden. Subjects and methods. In 1983, a random sample of 1870 subjects aged 45-65 years responded to a postal questionnaire (response rate 70.2%) including questions about sleep complaints and various diseases. Mortality data for the period 1983-95 were collected, and Cox proportional hazard analyses were used to examine the mortality risks. Results. At 12-year follow-up 165 males (18.2%) and 101 females (10.5%) had died. After adjustment for a wide range of important putative risk factors, difficulties initiating sleep (DIS) were related to CAD death in males [relative risk (RR), 3.1; 95% confidence interval (CI), 1.5-6.3; P < 0.01], but not in females. Short or long sleep duration did not influence risk of CAD mortality or total mortality for either gender. Depression in males increased the risk of death attributed to CAD (RR, 3.0; 95% Cl, 1.1-8.4; P < 0.05) and total mortality (RR, 2.2; 95% CI, 1.1-4.5; P < 0.05). Conclusion. These results provide evidence that there is an association between difficulties falling asleep and CAD mortality in males.