Sleep Variability and Abdominal Obesity in Adolescents: The Penn State Child Cohort

Introduction: Chronic sleep problems in adults have been associated with abdominal obesity and cardiometabolic disorders. However, associations between habitual sleep patterns and central obesity have not been fully understood, especially in adolescents. We investigated the associations between habitual sleep duration and its variability and body fat distribution in population-based adolescents of the Penn State Child Cohort (PSCC).

Methods: An actigraph (GT3X) and a sleep diary were used in 421 adolescents for 7 consecutive nights to calculate each individual’s nightly sleep time and sleep efficiency. We then calculated within-subject 7-night means and the standard deviations (SDs). The means being used as the individual’s habitual sleep duration and efficiency. The SDs were used as the individual’s habitual variability of sleep duration and efficiency. Body fat distribution was assessed using a standardized Dual-energy X-ray Absorptiometry (DX) system, including Andriod/Gynoid Fat Ratio, Android/Total Body Fat (%), and Gynoid/Total Body Fat (%). Linear regression models were used to evaluate the relationships between habitual sleep variables and the body fat distribution variables.

Results: The mean (SD) age was 16.7 y (2.3), with 52% male and 78% white. The mean (SD) of habitual sleep duration and its variability were 7.00 h (0.83) and 1.16 h (0.58) hrs. The mean (SD) of habitual sleep efficiency and its variability were 83% (6.3) and 7.01% (4.3), respectively. After adjusting for age, gender, race, and BMI percentile, 1-h increase in sleep-duration-variability, but not mean sleep duration, was associated with higher Android/Gynoid Fat Ratio (β=0.02, SE=0.01, p<0.05), and higher Android/Whole body Fat Ratio (β=0.21, SE=0.10, p=0.05) Neither habitual sleep efficiency, nor its variability were significantly associated with body fat distribution variables.

Conclusion:In adolescents, higher habitual night-to-night sleep-duration-variability, but not mean sleep duration, is significantly associated with abdominal ft distribution. Habitual night-to-night sleep variability is a novel risk factor associated with cardiometabolic morbidity.

Support: NIH R01 HL63772, ROI HL9165, UL1 RR033184, CO6 RR16499, UL TR000127