Longer sleep duration linked to lower coronary artery calcification

Participants who obtained one additional hour of sleep per night had a 33% decreased risk of coronary artery calcification, according to an objective sleep measurement.

The association between measured sleep duration and lowered coronary artery calcification remained after adjusting for potential confounders including education, sleep apnea risk and smoking status, and potential mediators such as lipid levels, BMI, blood pressure, inflammatory markers and alcohol consumption.

The research was conducted as an ancillary study of the Chicago cohort of the Coronary Artery Risk Development in Young Adults study. Data for 495 participants aged 35 to 47 years were available. Baseline data were collected from 2000 to 2001; outcome data from 2005 to2006.

Sleep metrics were measured objectively using a wrist activity monitor. A subjective measure was obtained using several self-reported patient sleep questionnaires. The researchers measured coronary artery calcification by CT. The primary outcome was the incidence of new calcification between the baseline and outcome years. Baseline observation of eligible participants revealed no detectable calcification.

Five-year incidence of coronary artery calcification was 12.3% (n=61). The adjusted reduced OR for calcification in participants with longer measured sleep duration was 0.67 per hour (95% CI, 0.49-0.91 per hour).

The magnitude of the observed association was similar to sizable differences in established coronary risk factors (eg, one additional hour of sleep reduced risk similarly to a reduction of 16.5 mm Hg in systolic blood pressure). No potential mediators appreciably altered the magnitude or significance of sleep.

JAMA.2008;300:2859-2866.