The Development of Healthy Lifestyle Behaviors Among US Children: Early Predictors and Associated Outcomes

Understanding the development of healthy lifestyle behaviors as well as its early predictors and associated outcomes is paramount, given the importance of healthy lifestyle behaviors in academic success, health, and well-being. In this dissertation, I conducted two studies to investigate the development of three modifiable lifestyle behaviors (i.e., physical activity, sedentary behavior, and sleep duration) in middle childhood, using a nationally representative sample of US children from the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11. Study 1 was designed to unpack the developmental associations among the three lifestyle behaviors by examining the transactional within-person associations and co-development. Moderate-to-vigorous physical activity (MVPA), video game use (as a measure of mentally active sedentary behavior), and sleep duration were reported by parents in 3rd through 5th grades. Results from the random intercept cross-lagged panel model showed that MVPA, video game use, and sleep duration were not transactionally related over time at the within-person level. Analysis with the multivariate latent growth curve model showed that changes in these lifestyle behaviors over time were not correlated either. These main findings were replicated across social contexts of socioeconomic status, gender, and race/ethnicity groups. Study 2 focused on investigating predictors and outcomes associated with developmental trajectories of the three lifestyle behaviors. Specifically, kindergarten self-regulation (rated by teachers) that reflects individual agency was examined as a predictor. Fifth grade externalizing and internalizing problems (rated by teachers), body mass index (assessed with weight and height), and academic achievement (assessed by reading, math, and science achievement) were included as mental health, physical health, and academic outcomes, respectively. Results showed that kindergarten self-regulation predicted initial levels (i.e., 3rd grade) of video game use and sleep duration. After controlling for the stability and other lifestyle behaviors, 5th grade externalizing problems and academic achievement were predicted by initial levels of sleep duration, and body mass index was predicted by initial levels of sleep duration and MVPA and changes in MVPA. Most of these findings were replicated in subsamples across social contexts. Overall, this dissertation provides important insight into the development of healthy lifestyle behaviors in US children.