Behavioral and Biological Rhythms in Children's Obesity-Related Health Disparities

PROJECT SUMMARY/ABSTRACT Pediatric obesity is considered an epidemic with striking disparities by socioeconomic status (SES). There is therefore a pressing need to identify novel, modifiable risk factors for obesity prevention and treatment in children, particularly those who are at greater risk. Compelling evidence that is rooted in circadian biology and

our understanding of circadian rhythms, and is supported by emerging work with rodents and adults suggests that in addition to focusing on how much we engage in eating, activity and sleep behaviors, it may also be important to understand the timing and consistency with which we engage in these behaviors (i.e., behavioral

rhythms) for obesity risk reduction. Mounting evidence demonstrates that behavioral rhythms that are aligned with underlying circadian rhythms, such as sleeping during the biological night and eating during the biological day are associated with improved metabolic processes and weight regulation. Although less is known

regarding how behavioral rhythms may optimize weight regulation in children, findings from related lines of pediatric research support those with rodents and adults and highlight the potential importance of behavioral rhythms for excess weight gain prevention. Understanding the role of behavioral rhythms in weight regulation

for children from lower SES backgrounds may be particularly important given that they may be at greater risk for disruptions to behavioral rhythms due to economic adversity and neighborhood disadvantage, placing them at increased risk for excess weight gain. Further, understanding associations between SES, behavioral

rhythms and weight regulation in young school-aged children focuses on a time period when a number of health behaviors that carry through adolescence are shaped and thus may represent an opportune time for optimizing weight regulation. The present study therefore proposes to enroll 176 children 5-8-years old from

diverse SES backgrounds into a 16-month observational study. Children will complete five 10-day assessments across the study (baseline, 4, 8, 12, and 16 months) during which the following will be measured: timing and consistency of sleep (via actigraphy), timing and distribution of eating (via 24-hour dietary recalls),

timing and consistency of physical and sedentary activities (via accelerometry and self-report), timing of the circadian clock (dim light melatonin onset; DLMO), measures of the home and neighborhood environment, and anthropometrics (height, weight, adiposity). The primary aims of this proposed work are to assess: a) how

behavioral rhythms affect body mass index (BMI) trajectories in children, and b) how SES affects behavioral rhythms and thus BMI trajectories. Secondary aims will assess how circadian factors (i.e., circadian phase and circadian phase angle) and the household and neighborhood environments affect behavioral rhythms.

Exploratory aims will also assess the relative influence of behavioral, circadian and environmental factors on children's BMI trajectories, including potential moderation of associations between behavioral rhythms and BMI trajectories by circadian phase and phase angle.