Cross-sectional and longitudinal associations between objectively measured sleep duration and body mass index: the CARDIA Sleep Study

Abstract

Numerous studies have found an association between shorter sleep duration and higher body mass index (BMI) in adults. Most previous studies have been cross-sectional and relied on self-reported sleep duration, which may not be very accurate. In the Coronary Artery Risk Development in Young Adults (CARDIA) Sleep Study (2000-2006), the authors examine whether objectively measured sleep is associated with BMI and change in BMI. They use several nights of wrist actigraphy to measure sleep among participants in an ongoing cohort of middle-aged adults. By use of linear regression, the authors examine whether average sleep duration or fragmentation is associated with BMI and 5-year change in BMI, adjusting for confounders. Among 612 participants, sleep duration averaged 6.1 hours and was grouped into 4 categories. Both shorter sleep and greater fragmentation were strongly associated with higher BMI in unadjusted cross-sectional analysis. After adjustment, BMI decreased by 0.78 kg/m(2) (95% confidence interval: -1.6, -0.002) for each increasing sleep category. The association was very strong in persons who reported snoring and weak in those who did not. There were no longitudinal associations between sleep measurements and change in BMI. The authors confirmed a cross-sectional association between sleep duration and BMI using objective sleep measures, but they did not find that sleep predicted change in BMI. The mechanism underlying the cross-sectional association is not clear.

Figure 1.

Timeline for the Coronary Artery Risk Development in Young Adults (CARDIA) Sleep Study, 2000–2006.

Figure 2.

BMI distribution by average actigraph-measured sleep duration, the CARDIA Sleep Study, 2000–2006. The gray boxes show the 25th, 50th, and 75th percentiles, and the tails show the largest and smallest values, excluding outliers. White women in the shortest sleep category (n = 2) and black men in the longest sleep category (n = 0) are not represented. BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults.

Figure 3.

Distribution of 5-year change in BMI by average actigraph-measured sleep duration, the CARDIA Sleep Study, 2000–2006. The gray boxes show the 25th, 50^th, and 75th percentiles, and the tails show the largest and smallest values, excluding outliers. White women in the shortest sleep category (n = 2) and black men in the longest sleep category (n = 0) are not represented. BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults.