The importance of sleep patterns in the incidence of coronary heart disease: a 6-year prospective study in Mashhad, Iran

Chronic shortened sleep can increase several cardiovascular risk factors, including depression, anxiety, metabolic syndrome, diabetes and hypertension. In the current study, we aimed to investigate the relationship between sleep patterns and the incidence of coronary heart disease (CHD). A total of 9704 healthy participants were recruited for the MASHAD cohort study. Within 6 years of follow-up, participants were categorized into four groups based on their number of hours of nightly sleep. Cox’s proportional hazard model was used to assess relative risks (RRs) and 95% confidence intervals (CIs). During the study, 235 heart problems, including myocardial infarction, stable angina and unstable angina, were confirmed. There were significant differences between men and women who had short and long nightly sleep (p < 0.05). The incidence of CHD was significantly higher in participants with very short night sleep durations than in those with longer hours of night sleep. The subjects with very short nightly sleep were more susceptible to unstable angina (RR: 2.614 (CI 1.354–5.047)) (p < 0.05). We found that shortened nightly sleep was associated with an increased incidence of coronary heart disease in an Iranian population. These findings suggest that sleep disorders, especially shortened night sleep, can be a risk factor for CHD.