Relationships Among Sleep, Physical Activity, and Weight Status in Children and Adolescents

Sleep and physical activity are both associated with multiple behavioral and metabolic health outcomes, and both behaviors have been linked to the development of weight status. Recent estimates suggest that many children are not meeting sleep recommendations or participating in adequate levels of physical activity, which may be related to the high prevalence of childhood overweight and obesity. Much of the research assessing these relationships has focused on adults and older children, and has relied on parent- or child-reported, cross-sectional research in predominantly White samples. Little work has focused on these relationships in very young children. Although more research has been conducted in adolescent samples, these studies rarely consider the effect of weeknights vs. weekend nights or physical activity intensity in their analyses. Therefore, the overall purpose of this dissertation was to examine the longitudinal relationships between sleep, physical activity, and weight status in both very young children and adolescents. This dissertation was comprised of three studies. The first study used data from the Linking Activity, Nutrition and Child Health (LAUNCH) observational study to evaluate longitudinal associations between sleep and physical activity in 6-24 month-old children. Device-based measures were used to assess daytime, nighttime, and 24 hour sleep durations, nighttime sleep awakenings, and daytime total physical activity. Linear mixed models assessed whether the within- and between-person effects of physical activity were associated with sleep. Children with higher total physical activity levels slept less during the day compared to children with lower total physical activity levels, and when children were more physically active compared to their own average physical activity levels, their 24-hour sleep duration was lower. Differences in nighttime sleep duration were seen based on race/ethnicity and SES. The findings indicate that mechanisms underlying the sleep and physical activity relationship in young children vary from those that have been suggested in older children and adults. The second study used data from the LAUNCH observational study to evaluate longitudinal associations between sleep and adiposity in 6-24 month-old children. Device-based measures were used to assess daytime sleep duration, nighttime sleep duration, and daytime total physical activity levels. Diet was assessed via questionnaires completed by the mother. Weight-for-length z-scores were calculated based on measures collected by trained data collectors. Linear mixed models assessed whether the within-and between-person effects of sleep were associated with adiposity. Physical activity and diet were entered into the models as covariates. Children had lower weight-for-length z-scores when they slept less at night compared to their own average nighttime sleep durations, although this relationship was attenuated by daytime physical activity. These associations did not vary based on race/ethnicity, gender, or SES. These results suggest that the relationship between sleep and adiposity is specific to infant’s nighttime sleep durations, and that physical activity has a protective effect on the development of adiposity in very young children. The purpose of the third study was to assess longitudinal associations between sleep and physical activity in adolescent children who participated in the Next Generations Health (NEXT) Study. Both sleep and physical activity were measured via survey. Surveys asked about weeknight and weekend night sleep separately, and separate questions assessed total physical activity (TPA) and vigorous physical activity (VPA). Linear mixed models assessed whether TPA and VPA were associated with sleep, with separate models created for weeknight and weekend night sleep. For every extra day adolescents met TPA guidelines, they slept 31 minutes less per night on weekend nights. This difference increased by nearly 2 minutes per night for every 1 year increase in age. Adolescents who participated in \u3e7 hours of VPA in the past week slept 216 minutes longer per night on weekend nights than adolescents who did not participate in VPA, and this difference decreased by 13 minutes per night for every 1 year increase in age. Differences in sleep duration were seen based on race/ethnicity, gender, and SES. These findings indicate that both physical activity intensity and day type are important factors to consider when assessing the sleep and physical activity relationship in adolescents. Although both sleep and physical activity are important behaviors that should be included in interventions targeting obesity prevention, it should be noted that the complex relationships between sleep, physical activity and adiposity in children and adolescents may not follow the same patterns as those seen in adults. This is not surprising considering both sleep and physical activity vary greatly as individuals develop from infancy to adulthood. Furthermore, the differences that were seen in sleep duration by different demographic characteristics suggest that more work is needed addressing the large-scale social determinants of health that are directly related to sleep in order to improve sleep in at-risk populations. Collectively, results from the studies included in this dissertation suggest that future research addressing the relationships among sleep, physical activity, and adiposity should consider physical activity intensity as well as the timing of sleep, whether this be daytime vs. nighttime sleep or weeknight vs. weekend night sleep. Obesity prevention research that focuses on increasing sleep and physical activity must take the age of the children into consideration, as well as demographic characteristics that may play a role in both sleep and physical activity levels

Longitudinal Association of Biological Maturation With Physical Activity Behaviors in Girls Transitioning From 5th to 7th Grade

Introduction This longitudinal study determined if social cognitive variables influence physical activity in girls stratified on the basis of maturity status. Methods Participants attended South Carolina public schools (Mage in 5th grade = 11.1 years) and included a cohort of 529 girls who provided physical activity data in the 5th grade and in 6th and/or 7th grade. The measure of maturity status was age at peak height velocity (APHV) estimated from maturity offset when the children were in the 5th grade. The Earlier Maturity (EM) group included girls whose APHV was one standard deviation or more below the mean APHV for the full sample. All other girls were placed in the Later Maturity (LM) group. Physical activity was assessed at each time point via accelerometry. Social-cognitive variables were assessed at each time point by a questionnaire measuring self-efficacy, enjoyment, competence, appearance, fitness, and social motives for physical activity. Growth curves for the total, Earlier Maturing, and Later Maturing groups assessed relationships between physical activity over time and time-varying social cognitive variables. Results Physical activity was lower in the Earlier Maturing group and was positively associated with self-efficacy and enjoyment motivation in the total group. These relationships were observed in the 5th grade and maintained through 7th grade. In the Later Maturing group, we observed positive relationships between physical activity and self-efficacy, enjoyment and competence motivation. Conclusions Strategies to increase confidence, skills, and enjoyment of physical activity may only be effective for promoting activity among later maturing girls

Linking Activity, Nutrition, and Child Health (Launch): Protocol for a Longitudinal Cohort Study of Children as They Develop From Infancy to Preschool Age

Background Physical activity is known to provide important health benefits in children ages 3 years and above, but little is known about the effects of physical activity on health in very young children under age 3. LAUNCH (Linking Activity, Nutrition, and Child Health) is a study designed to expand the body of knowledge on development of physical activity behavior and associations between physical activity and other health characteristics as children transition from infancy to preschool age. Methods Physical activity and sedentary behavior will be measured objectively in young children over a period of 30 months. Each child will complete a measurement protocol at 6, 12, 18, 24, 30 and 36 months of age. The following factors will be measured at each time point: physical activity, sedentary behavior, anthropometric characteristics, and motor developmental status. Objectively-measured sleep behavior will be included as an optional component of the protocol. Parents will provide information on demographic factors, parenting behaviors, home and childcare characteristics, and the child’s dietary and sleep behaviors. Discussion LAUNCH will employ a longitudinal study design and objective measures of physical activity, sedentary behavior and sleep in examining developmental trends for those characteristics in children between the ages of 6 and 36 months. Associations among physical activity, sedentary behavior, sleep, and weight status will be examined. Findings will inform public health guidance and intervention strategies for very young children

Harnessing technology and gamification to increase adult physical activity: a cluster randomized controlled trial of the Columbia Moves pilot

Abstract Background The use of health technologies and gamification to promote physical activity has increasingly been examined, representing an opportunistic method for harnessing social support inherent within existing social ties. However, these prior studies have yielded mixed findings and lacked long-term follow-up periods. Thus, a pilot cluster randomized controlled trial was conducted to gauge the feasibility and preliminary efficacy of a digital gamification-based physical activity promotion approach among teams of insufficiently active adults with existing social ties. Methods Teams (N = 24; 116 total participants) were randomized to either a 12-week intervention (Fitbit, step goals, app, feedback; TECH) or the same program plus gamification (TECH + Gamification). Mixed effects models were used to compare group differences in treatment adherence, and changes in social support, steps, and moderate-to-vigorous physical activity at 12 weeks and 52 weeks from baseline, adjusted for sociodemographic characteristics and team size. Results TECH had a lower mean number of days of Fitbit self-monitoring versus TECH + Gamification during the intervention (adjusted difference: -.30; 95% CI, -.54 to -.07; P = .01). Post-intervention, TECH had 47% lower odds of self-monitoring 7 days per week versus TECH + Gamification (.53; 95% CI, .31 to .89; P = .02). No differences were observed between TECH + Gamification and TECH in increases in social support (0.04; 95% CI, -.21 to .29; P = .76), ActiGraph-measured daily steps (-425; 95% CI, -1065 to 215; P = .19), or moderate-to-vigorous physical activity minutes (-3.36; 95% CI, -8.62 to 1.91; P = .21) from baseline to 12 weeks or in the regression of these improvements by 1 year (Ps > .05). Although not significant in the adjusted models (Ps > .05), clinically meaningful differences in Fitbit-measured daily steps (TECH, 7041 ± 2520; TECH + Gamification, 7988 ± 2707) and active minutes (TECH, 29.90 ± 29.76; TECH + Gamification, 36.38 ± 29.83) were found during the intervention. Conclusions A gamified physical activity intervention targeting teams of adults with existing social ties was feasible and facilitated favorable, clinically meaningful additive physical activity effects while in place but did not drive enhanced, long-term physical activity participation. Future investigations should explore optimal team dynamics and more direct ways of leveraging social support (training teams; gamifying social support). Trial registration Clinicaltrials.gov ( NCT03509129 , April 26, 2018)