0012 Night Owls and Morning Birds Fly Over the Gym: Circadian Misalignment Does Not Predict Physical Activity in Adolescents

Abstract

Abstract Introduction Given that obesity rates have reached epidemic-level proportions in the U.S., it is more important than ever to identify preventative interventions to reduce obesity risk. Many aspects of sleep have been associated with obesity through their relationship to physical activity. Circadian misalignment is an area of sleep that is yet understudied but that may be especially relevant given the rapid biological and social changes in sleep timing seen in adolescence. This study examined the relationship between circadian misalignment and physical activity among adolescents. Methods Fifty adolescents completed an 11-day protocol that began with a baseline appointment where study staff measured participants’ height and weight. Over the next 10 days, participants wore waist accelerometers that measured physical activity and completed manual sleep diaries. After 10 days, participants completed a six-hour appointment in a dimly lit room (lux level < 5) where study staff collected saliva samples every 30 minutes to measure the onset of participants’ melatonin levels. In this preliminary analysis, circadian misalignment was calculated by subtracting the timing of melatonin onset from the average bedtime noted in participants’ sleep diaries; lower scores are reflective of greater circadian misalignment. Results Adolescents engaged in 12,038.77 minutes (SD=1737.62) of sedentary activity, 767.29 minutes (SD=260.93) of light physical activity, and 1,263 (SD= 411.89) of moderate-to-vigorous physical activity across this ten-day monitoring period. We conducted multiple regression analyses with circadian misalignment as a predictor of sedentary, light, and moderate-to-vigorous physical activity levels. Circadian misalignment was not a statistically significant predictor of sedentary physical activity (p=.85), light physical activity (p=.70), or moderate-to-vigorous physical activity (p=.30). Conclusion In our study, circadian misalignment did not predict sedentary, light, or moderate-to-vigorous physical activity levels. Current literature on other facets of sleep suggests that sleep duration and quality is related to physical activity. However, our results suggest that improving circadian alignment may not be a viable intervention to increase physical activity. Further studies are needed to validate these results as well as to explore the effects of circadian alignment on other aspects of obesity risk. Support (if any)