Abstract P142: Social Jetlag is Associated With Adiposity in 8-10 Year Old New Zealand Children

Abstract

Background: Childhood obesity has been associated with poor sleep behaviour, including sleep duration, sleep disorders and social jetlag. Social jetlag is the discrepancy between an individual’s circadian clock and social rhythms, and is measured as the difference in hours between the midpoint of sleep at work/school and free days. While social jetlag has been associated with being overweight adults, no known studies have examined whether obesity is associated with social jetlag in children. We hypothesized that poor sleep behavior, including sleep duration, sleep disorders and social jetlag, would be associated with body composition in in 8-10 year old New Zealand children. Methods: This cross-sectional study recruited 341 children (50% F) aged 8-10 years from three representative sample sites across New Zealand. Four dependant variables were calculated: body fat (%), fat mass index (FMI, kg/m 2 ), waist to hip ratio (WHR), and body mass index (BMI, kg/m 2 ). The three independent variables were: average sleep duration, social jetlag, and sleep disorders. Sleep duration was recorded using a parent-reported, single item habitual school/weekday sleep survey. Social jetlag was calculated as the absolute difference between the midpoints of sleep on weekdays versus weekend days. Sleep disorders were estimated using the Children’s Sleep Habits Questionnaire. Results: Following adjustment for confounders, sleep duration was only associated WHR ( β = -0.008, 95%CI: -0.015, 0.000), and sleep disorders was only associated with FMI ( β = -0.034, 95%CI: 0.002, 0.067 kg/m 2 ), while social jetlag was associated with all four body composition variables. A one hour increase in social jetlag was associated with a 2.98 % (95%CI: 0.41, 5.55 %) increase in body fat, 0.51 kg/m 2 (95%CI: 0.11, 0.91 kg/m 2 ) increase in FMI, a 0.90 kg/m 2 95%CI: 0.21, 1.58 kg/m 2 ) increase in BMI, and a 0.13 (95%CI: 0.003, 0.023 increase in WHR. Conclusions: In conclusion, Social jetlag may be a particularly important sleep behaviour correlate of adiposity in children. Moreover, social jetlag provides an opportunity for a relatively simple and measurable public health strategy.