Habitual sleep patterns and the distribution of body mass index: cross-sectional findings among Swedish men and women

Objective: To compare distributions of body mass index (BMI) between individuals with different habitual sleep patterns. Methods: We performed cross-sectional analyses of 40,197 Swedish adults (64% women), who reported sleep duration and quality, weight, height, and possible confounding factors in 1997. Using quantile regression, we estimated associations between sleep patterns and selected percentiles of the distribution of BMI. Results: While the medians were similar, larger adjusted values of BMI were estimated in the upper part of the distribution among men and women with short sleep (<= 5 h) compared with medium-length sleep (6-8 h). For example, in men, the 90th percentile of BMI was 0.80 kg/m(2) (95% confidence interval: 0.17-1.43 kg/m(2)) higher among short sleepers. In women, long sleepers (>= 9 h) also showed larger values in the upper part of the BMI distribution; the 90th percentile was 1.23 kg/m(2) (0.42-2.04 kg/m(2)) higher than in medium-length sleepers. In male long sleepers, smaller values were estimated in the lower part of the BMI distribution; the 10th percentile was 0.84 kg/m(2) lower (0.35-1.32 kg/m(2)) than in medium-length sleepers. The 90th percentile of BMI in women with poor-quality compared with good-quality sleep was larger by 0.82 kg/m(2) (0.47-1.16 kg/m(2)); the 10th percentile was smaller by 0.17 kg/m(2) (0.02-0.32 kg/m(2)). Conclusions: Short, long or poor-quality sleepers showed larger, or smaller, values at the tails of the BMI distribution, but similar medians. Hence, unfavorable sleep patterns and BMI were associated only in a subset of this study population. (C) 2014 Elsevier B. V. All rights reserved.