Project Summary With our ethnically and socioeconomically diverse longitudinal twin study, in this competing continuation we aim to understand the genetic and environmental mechanisms linking sleep and physical health across pubertal development. We also elucidate mechanisms accounting for longitudinal associations between these health processes and both mental health and inflammation in adolescence. Further, we examine a key proximal sociocultural process - daily media use - which is pervasive in the everyday lives of adolescents. With inflammation and mental health problems on the rise among youth, it is imperative that we utilize a well- powered (N=700 twin youth), representative (recruited from birth records), genetically-informed (twin study), longitudinal (followed since infancy with proposed assessments at 12 and 14 years) design to identify risk and resilience processes across the major transition from childhood to adolescence. To date, our results suggest that sleep is linked with cognition and health for genetic rather than environmental reasons (see C1), suggesting that third variables are involved that may vary by development (puberty). More specifically, we add two follow ups of a diverse twin sample recruited from birth records and assessed at 1, 2, 5, 8, 9, 10 & 11 years (N=700 youth; Arizona Twin Project). At 12 years, we add new assessments of the environment (e.g. media use) and extend our objective measures of sleep and health (aerobic, muscular, adiposity, physiology). At age 14, we add new outcome assessments (inflammatory biomarkers, mental health). Under Aim 1, we use parallel process growth models from childhood into adolescence to determine direction of effects among puberty, sleep, and multiple indicators of health. Under Aim 2, we dynamically extend this work by using intercepts and growth parameters from the parallel process growth models outlined in Aim 1 to predict inflammation and mental health at age 14. Under Aim 3, we examine the genetic and environmental overlap among puberty, sleep, and health and pinpoint aspects of the environment that play a role in health. Such an examination is critical as our work has shown that common risk factors and health are often associated for genetic as opposed to environmental reasons which can shift the focus of potential interventions. Under Aim 4, we disentangle genetic and environmental contributions to associations between daily sociocultural contexts, sleep and health. The proposed study builds on existing collaborations with complementary expertise. The project is notable as it is the only twin sample of youth to obtain longitudinal objective sleep, health, and sociocultural context data, for its developmental cultural and genetic approach that uncovers gene-environment interplay, measurement of physiological and inflammation biomarkers, and examination of proximal sociocultural processes including objective media use in adolescence. Combining these design features exponen...