Sleep Duration Is Associated With Carotid Intima-Media Thickness Among Men in the Coronary Artery Risk Development in Young Adults ( CARDIA ) Study

A growing body of evidence suggests that sleep duration may be a potential risk factor for cardiovascular disease (CVD). Findings have been somewhat inconsistent both as to whether there is a significant association and whether it differs by sex. Evidence suggests that “shorter sleepers,” those reporting sleeping <6 hours, and “longer sleepers,” those reporting sleeping >8 hours, have earlier CVD mortality compared with those sleeping 7 to 8 hours. One limitation of these studies is that most used selfreported sleep duration, which can introduce misclassification leading to biased estimates. Studies using objective measures of sleep duration may provide better evidence regarding the association between sleep duration and CVD. Furthermore, given that there are sex differences in both sleep characteristics and in subclinical CVD, studies that investigate the potential differences by sex will add to our understanding of the relationships between sleep duration and CVD risk. Recent studies found associations between sleep duration and risk factors for CVD such as blood pressure, lipids, metabolic syndrome, and subclinical markers of coronary atherosclerosis such as coronary artery calcification. Carotid intimamedia thickness (CIMT) serves as a potential subclinical marker of CVD risk and has been associated with increased risk of myocardial infarction and stroke. CIMT may be involved in the association between sleep duration and CVD; however, evidence is needed using an objective assessment rather than selfreported sleep. Consequently, the primary aim of this study was to evaluate associations between objectively assessed sleep duration (using actigraphy) and CIMT among participants from the Coronary Artery Risk Development in Young Adults (CARDIA) Study and determine whether the associations vary by sex. Background and Purpose—Carotid intimamedia thickness (CIMT) is a subclinical marker of cardiovascular disease. Recent studies suggest that shorter sleep duration is a risk factor for cardiovascular disease, but there is limited evidence regarding this association using highquality, objective assessments of sleep. The aim of this study is to determine whether sleep duration is associated with CIMT. Methods—The study used an observational cohort consisting of 617 black and white middleaged healthy participants (37–52 years; 58% female) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Multivariableadjusted linear regression analyses were performed. Sleep duration was measured using wrist actigraphy monitors. CIMT was calculated using the average of 20 measurements of the mean common carotid, bulb, and internal CIMT, which was assessed using ultrasound images. Results—After adjusting for covariates, 1 hour of longer sleep duration was associated with 0.026 mm less CIMT among men (P=0.02; 95% CI, −0.047 to −0.005) and 0.001 mm less CIMT among women (P=0.91; 95% CI, −0.020 to 0.022). Segmentspecific analyses indicated that the carotid bulb was a key driver of the observed association. Conclusions—Shorter objectively assessed sleep duration was associated with greater CIMT among men but not women. (Stroke. 2012;43:2858-2864.)