0812 Modelling the Impact of Reallocating Sleep and Physical Activity on Anxiety and Depression Symptoms in Adolescents

Abstract Introduction Insufficient sleep and sedentary behavior, both associated with increased anxiety and depression symptoms, are highly prevalent in US adolescents. Our lab previously found that extending adolescents’ sleep duration decreased sedentary behavior (SB). However, the impact of replacing time spent in unhealthy behaviors (e.g., SB) with healthy behaviors (e.g., sleep, light physical activity [LPA], moderate-to-vigorous physical activity [MVPA]) on mental health is unknown. Therefore, we aimed to understand the impact of replacing SB and time-in-bed (TIB) with LPA and MVPA on anxiety and depression symptoms in habitually short-sleeping adolescents using isotemporal modeling. Methods Baseline data from a study of habitually short-sleeping (≤7 hours on school nights) and physically inactive (< 3h MVPA/week) adolescents ages 14-19 years were analyzed. During one week of home monitoring, thigh-worn accelerometry assessed SB, LPA, and MVPA; wrist-worn actigraphy estimated TIB. Participants completed PROMIS Anxiety and Depressive Symptoms scales. Isotemporal substitution modeling, which uses cross-sectional data to predict the effect of reallocating time spent in one activity with an equal amount of time spent on another, was used to estimate the effect of movement behavior reallocation on mental health symptoms. Results Thirty-four adolescents completed study measures (age=16.0±1.2 years, 70% female, 88% Non-Hispanic White). Reallocating 1 hour/day of SB to an equal amount of LPA within the model was associated with a 4.5-point improved depression T-score (p=0.019) but no difference in anxiety symptoms (p>0.10). Neither replacing 1 hour/day of SB with TIB or MVPA nor replacing 1 hour/day of TIB with LPA or MVPA within the model were associated with changes in depression or anxiety symptoms (all p>0.10). Conclusion Replacing 1 hour/day of SB with LPA but not MVPA was associated with significantly lower depression symptoms in habitually short-sleeping, physically inactive adolescents. However, neither reallocation of SB to TIB nor of TIB with PA was associated with mental health symptoms. As this modeling analysis is cross-sectional in nature, further prospective research is needed to evaluate the impact of replacing SB with healthy behaviors, including meeting recommended sleep and PA guidelines, to determine impacts on adolescent wellbeing. Support (if any) NIH NIDDK K23DK117021; NIH BIRCWH 2K12HD057022; NIH CTSA UL1TR002535