As screen time (ST) constitutes an integral part of the daily lives of young children today, parents, educators, and researchers have started to explore the associations of ST with children’s cognitive, behavioral, and social outcomes. The majority of existing studies have primarily focused on the duration of ST in relation to these outcomes despite the importance of other aspects such as content and type of device in the context of an evolving digital landscape marked by high mobility, ubiquity, and diversity. Addressing this gap, the current study aimed to explore the intricate relations between multiple aspects of ST (i.e., duration and content), executive function (EF) difficulties, and school adjustment in school-aged children, with a particular focus on the mediating role of EF difficulties linking the relations between ST and school adjustment. The current study employed data from the Panel Study on Korean Children, tracking 1,484 South Korean children from third to fourth grade. The duration of ST was measured by the average daily hours spent on smart devices and computers. Parent reports of the levels of engagement in recreational and educational ST and EF difficulties were assessed on Likert scales. School adjustment was reported on by teachers. The results from a half-longitudinal mediation model demonstrated that more frequent engagement in educational ST was related to fewer EF difficulties, which was in turn associated with better school adjustment. The current findings suggest that multiple approaches are needed to effectively guide children’s ST use in their everyday lives and interventions that target EF might be an effective way to promote children's behavioral and social adjustment in school settings.

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.

Sleep is an extremely important component of living a healthy life than can impact development and behavior starting in childhood. We expanded on past research regarding this topic to determine the role of childhood sleep and the onset of problem behaviors (externalizing and internalizing behaviors) among a sample of school-aged children. We predicted that lower sleep duration, decreased sleep efficiency, and prolonged sleep latency along with negative sleep habits would be associated with problem behaviors. Our sample was made up of 381 school-aged children (M = 8.49 years old, 49.6% female, 56% Caucasian) who were recruited through the Arizona Twin Study when the children were 12 months old. Mixed-model regressions included sex, socioeconomic status, and zygosity as covariates. Correlations and mixed-model regressions showed a significant relationship between negative sleep habits and problem behaviors (both externalizing and internalizing). Our results revealed that those who experience higher amounts of parent-reported negative sleep habits also demonstrate externalizing behaviors (aggression) and internalizing behaviors (anxiety). The findings in the current study are consistent with past research on this topic and suggest that poor sleep impacts daytime functioning and behavior.

Academic success in childhood is crucial for later academic, occupational, and life success (Heckman, 2006; Kuncel, Hezlett, & Ones, 2004; Spengler, Brunner, Damian, Lüdtke, Martin, & Roberts, 2015). Recent research suggests sleep is important for academic success but lacks objective measures of sleep (Buckhalt, El-Sheikh, Keller, & Kelly, 2009; Curcio, Ferrara, & De Gennaro, 2006; Dewald, Meijer, Oort, Kerkhof, & Bögels, 2010; Philbrook, Hinnant, Elmore-Staton, Buckhalt, & El-Sheikh, 2017). The purpose of this study was to examine the relations between sleep and academic success among children through objective measures of sleep in order to expand on the literature. Our sample consisted of 381 twins (50.4% male; 56% Caucasian; 36.5% same sex dizygotic) participating in an 8-year assessment from a longitudinal twin study. Actigraphy was used to assess sleep while various measures were used to assess academic success. A series of mixed model regressions were used to test the main predictions, with family entered as a random effect. Sex, age, Hispanic, SES, and zygosity were controlled for. Significant negative relations were revealed between sleep latency and reading and sleep latency and school liking. Additionally, SES was the most consistent significant positive predictor of our measures of academic success. These results suggest sleep and effects of SES should be considered when developing ways to help children’s school performance.

College and university students are heavily influenced by their exposure to opportunities, individuals, and belief-systems during their time in school. More specifically, countless students are impacted by campus Christian ministries. There are 67 registered religious clubs and organizations across Arizona State University's four campuses, and 46 of them identify as Christian. Similar to most faith-based organizations, Christian campus ministries seek to impact the lives of students. This study will take a look at the influence of these ministries at ASU by researching their intersection with another key component of university life: wellness.
The primary research question is, “How does involvement in Christian ministries at ASU relate to the wellness of students?” The study will examine multiple dimensions of wellness: occupational, physical, social, intellectual, spiritual, and emotional. Each component is essential to understanding the health and well-being of an individual, which is why this study will measure wellness levels in each dimension among samples of students at ASU.
The methodology chosen was a short, anonymous survey that 148 ASU students participated in—73 involved in Christian ministries at ASU and 75 not involved. The quantitative component included a wellness assessment using questions from The National Wellness Institute. These wellness scale questions were broken up into 5 randomized sections, each with one question per dimension, for 30 questions total. Each question response was assigned a rating on a 1 to 5 scale, 1 associated with low wellness and 5 high wellness. The qualitative component, comprised of short answer questions, only applied to students who were involved in a Christian ministry. This portion allowed respondents to explain if and how the ministry impacts each dimension of wellness uniquely.
The quantitative results showed some evident differences between students involved in Christian ministries and students not involved. The social and spiritual dimensions concluded much higher levels of wellness for involved students, both statistically significant with p-values of 0.028 and 0.004. Although some of the wellness differences between involved and not involved participants were not statistically significant, there is also notable variation among questions within each dimension. For the qualitative data, most students in Christian ministries said they believe their involvement increases their wellness in all six dimensions. For each dimension, over 75% of participants said that the ministry impacted their well-being. For the social, spiritual, and emotional dimensions, at least 97% of respondents said their ministry involvement impacted their wellness.
In examining the conclusions of the study, one recommendations is to strengthen the partnership between the greater ASU community and Christian ministries by collaborating and combining resources for programming that relates to their common goals and shared values. Additionally, other faith-based organizations at ASU may benefit from replicating this study to observe their unique wellness impact.

Approximately 95% of Americans have at least one sibling (Weaver, Coleman, & Ganong, 2003), making it more likely that children grow up with a sibling than with a father (Lyon, 2009). It is therefore somewhat surprising to learn that sibling relationships have not been a central focus of psychological research, especially considering the fact that parent-child and peer relationships have been studied so extensively. There is no doubt that parents and peers have profound effects on children's emotional, psychological and social wellbeing, but siblings have important effects as well. By middle childhood, children spend more time with their siblings than they do with their parents (Pike, Coldwell, & Dunn, 2005). The sibling relationship is one of the longest and most lasting relationships that we as humans have. Approximately 78% of Americans over the age of sixty still have contact with at least one sibling (Cicirelli, 1995). Unlike parents, siblings are often in our lives until the end of our lifespan and, unlike friends, we do not choose them. They act as teachers, friends, and critics, just to name a few, and they are often a sounding board off of which we can test our ideas and behaviors. The focus of the current study is on the twin sibling relationship quality in middle childhood and in adolescence and its implications for individual adjustment, specifically in the realm of prosocial and aggressive behaviors. I evaluated twin sibling cooperation and conflict at both age 7-8 years and age 12-14 years and then examined prosocial and aggressive tendencies concurrently and longitudinally to study the strength of the association between the two. This study also aimed to better understand the extent to which prosocial behavior and aggression are influenced by genetic and environmental factors.

The predictors of school engagement in early childhood were examined, and mechanisms to improve classroom engagement levels were proposed for interventionists to consider. Literature was reviewed on the relations of child characteristics (i.e. effortful control, negative emotionality) and environmental characteristics (i.e. teacher-child relationship quality, classroom environment) to children's school engagement. Finally, a logic model was developed to guide future intervention work.

I would first like to thank Nikki Kontz, my project liaison from Teen Lifeline for her support and collaboration throughout the entire project. Secondly, I would like to thank my project mentor Professor Larry Dumka for his invaluable guidance, whose help as well as that of the entire CARE cohort made the project possible. Last but not least, a special thanks goes out to the Teen Lifeline crisis counselors and staff for gathering all the data needed to complete this study. Lastly, I would like to thank Carlos Valiente and Erin Pahlke who took the time to serve on my thesis committee.

Christian psychotherapy appears to be useful especially for Christian clients seeking therapy, and is a growing preference among this population. Thus, the need for research on the efficacy and effectiveness of Christian interventions must be recognized. This study reviews 13 effectiveness and 21 efficacy studies of Christian psychotherapeutic interventions in various areas of psychotherapy. The majority of effectiveness and efficacy studies were shown to give positive outcomes for Christian psychotherapy, and overall, Christian psychotherapy is promising as an effective alternative to secular therapy. The need for further research in most areas is discussed.

This project aimed to compile a comprehensive directory of faith congregations in the city of Tempe that would be willing to participate in the Interfaith Homeless Emergency Lodging Program (I-HELP). I-HELP is a non-profit sector of the Tempe Community Action Agency (TCAA) that successfully houses Tempe's homeless population by the generous participation of faith congregations. 5 participants out of the 75 contacted completed the survey. These congregations were found on Google Maps and were contacted through the means of telephone, email, and personal introductions.