Doctoral Dissertation Research in DRMS: The effects of weight status and sleep duration on adolescent cognitive functioning and food choice

Obesity represents one of our nation’s leading public health issues. In 2017, over 30% of U.S. high school students had either overweight (15.6%) or obesity (14.8%), and the average U.S. BMI continues to rise.

Overall, this increasing trend is associated with earlier mortality and lower quality of life. Weight loss interventions typically target food intake and exercise, but maintenance of weight loss after these interventions is poor. Therefore, it is important to identify other factors beyond food intake and exercise that may contribute to improved prevention and treatment of overweight and obesity.

This study aims to do this by investigating the roles of sleep and cognitive function (e.g. impulsivity) in relation to weight. Past research has demonstrated that poor cognitive function may lead to less healthy food choices. Poor sleep may exacerbate this problem, particularly in individuals with overweight and obesity that may be more vulnerable to changes in cognitive function following short sleep.

Given these relationships, sleep may represent a target to prevent weight gain and improve obesity interventions. However, more research is needed to understand the relationships between weight, sleep, cognitive function, and food intake. This research investigates these relationships by having adolescents with normal weight and with overweight or obesity complete two sleep conditions, one in which they sleep for 4.5 hours for two nights and one in which they sleep for 9 hours for two nights.

Each condition is followed by a self-serve breakfast and tests of cognitive function to assess the effects of weight status and sleep duration on food intake and cognitive function. The findings inform current obesity prevention programs and weight loss interventions and increase understanding of the factors related to weight gain.

Overweight and obesity (OWOB) has traditionally been explained through energy balance, with weight loss interventions focusing on decreased food intake and increased energy expenditure. However, interventions targeting these mechanisms often fail to produce long-term changes in adiposity. Thus, identification of additional modifiable mechanisms is critical.

For example, aspects of executive function, including cognitive flexibility and impulsivity, have been shown to be impaired in individuals with OWOB and may predict increased food consumption. Importantly, sleep restriction, which is common in adolescents with OWOB, also impairs cognitive function. Further, current fMRI evidence suggests that adolescents with OWOB are more vulnerable to changes in reward sensitivity following sleep restriction as compared to peers with normal weight (NW).

However, this relationship has not been well evaluated in relation to performance-based cognitive function. Thus, this study aims to expand on present literature by exploring the roles of adiposity, sleep, and performance-based cognitive function in relation to observed food choice. Using a randomized crossover design, participants with NW and with OWOB will complete two conditions in a randomized order: a sleep-restricted condition in which participants sleep 4.5 hours for two nights and an adequate sleep condition in which participants sleep 9 hours for two nights.

Conditions are separated by a 2-night washout period to prevent carryover effects. On the last night of each sleep condition, participants fast for 10 hours overnight before attending a morning lab visit. Upon arrival, they are given a self-serve breakfast of whole and processed breakfast foods, and food choice is measured.

Following the self-serve breakfast, participants complete the Stroop test and NIH Toolbox Cognition Battery. Key relationships assessed are: 1) the relationships between body fat percent and outcomes of food choice and cognitive function; 2) the unique effects of, and interaction between, sleep and body fat percent in predicting food choice and cognitive outcomes; 3) the effects of cognitive function as a moderator in the relationship between adiposity and food choice when adolescents are adequately rested and sleep restricted.

Overall, the findings strengthen foundational understanding of the cognitive mechanisms underlying OWOB and food choice, serving as a framework for future research in fields such as health behavior, physiology, and cognitive neuroscience. This project informs obesity prevention and treatment programs as well as public policy regarding adolescent academic environments and sleep guidelines.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.