Beyond sleep duration: distinct sleep dimensions are associated with obesity in children and adolescents

OBJECTIVE: Short sleep duration is recognized as a significant risk factor in childhood obesity; however, the question as to how sleep contributes to the development of obesity remains largely unknown. The majority of pediatric studies have relied on sleep duration as the exclusive measure of sleep; this insular approach may be misleading given that sleep is a dynamic multidimensional construct beyond sleep duration, including sleep disturbances and patterns. Although these sleep dimensions partly overlap, it is necessary to determine their independent relation with obesity, which in turn, may inform a more comprehensive understanding of putative pathophysiological mechanisms linking sleep and obesity. The aim of the present study was to investigate whether sleep dimensions including sleep duration, disturbances, and patterns were individually associated with obesity, independent of multiple covariates. The second objective was to examine whether sleep disturbances and patterns were independently associated with obesity, after adjusting for sleep duration. METHODS: Participants included 240 healthy children and adolescents (M-age = 12.60, s.d.= 1.98; 45.8% females). Anthropometric measures included measured waist and hip circumference, body mass index Z-score, and percent body fat. Subjective sleep measures included sleep duration, sleep disturbances, sleep quality, and sleep patterns from youth- and parental report. RESULTS: Youth with larger adiposity and body composition measures reported poorer sleep quality (beta(avg) = 0.14, P < 0.01), more sleep disturbances (beta(avg) = 0.13, P < 0.05), and showed a delayed sleep phase pattern (beta(avg) = 0.15, P < 0.05), independent of age, sex, pubertal status, physical activity, screen time, socioeconomic status, and sleep duration. Shorter sleep duration was significantly associated with obesity; however, this link was attenuated after adjustment of covariates. CONCLUSIONS: The results suggest that sleep measures beyond duration may more precisely capture influences that drive the negative association between sleep and obesity, and thus, yield more robust associations. As such, future studies are needed to better understand how distinct sleep dimensions confer risk for childhood obesity. International Journal of Obesity (2013) 37, 552-558; doi:10.1038/ijo.2013.4; published online 19 February 2013