0876 Sleep and Body Mass Index: The Enduring Effects of Sleep Duration and Wake After Sleep Onset in College Students

Abstract

Abstract Introduction College students are an at-risk population for poor sleep health and higher body mass index (BMI), which are both linked to negative health outcomes later in life. Most studies examining the relationship between sleep and BMI are cross-sectional or have collected self-reported sleep data. Therefore, the current study aimed to examine the longitudinal relationship between an objective measure of sleep assessed with a Phillips Respironics Actiwatch 2 device and BMI in college students. It was hypothesized that poorer sleep health would be related to higher BMI. Methods At three time points across the first two years of college (i.e., 8 months apart), participants (N=116) wore an Actiwatch 2 device for one week and had their height and weight measured. The sample demographics were 71% female, 72% White or Caucasian, and an average BMI of 24.07. Sleep health was defined by sleep duration, wake after sleep onset (WASO), sleep fragmentation, and midpoint of sleep. Each variable was scored as weekday (Sunday to Thursday) or weekend (Friday and Saturday). Results A linear mixed effects model using R was conducted after a person-mean variable (between person) and a person-mean centered variable (within person) were created for each participant. Weekday person-mean sleep duration was negatively related to BMI (t = -2.81), indicating shorter sleep duration was related to higher BMI across time. After controlling for between person effects, there were enduring relationships between both person-mean centered sleep duration (t = -3.12) and WASO (t = 2.06) and BMI, indicating that shorter sleep duration and greater WASO was related to higher BMI within participants across time. No significant relationships were found between weekend sleep variables and BMI. Conclusion The current findings add to a growing literature indicating that poor sleep health is related to increased BMI. In particular, the findings indicate that shorter sleep duration and greater WASO may increase risk for weight gain across time but are specific to weekday sleep behaviors. Although alterations in biological and behavioral processes likely serve as the mechanisms by which these variables influence BMI, additional research is needed to understand how this occurs and why weekday sleep behaviors are particularly important. Support (if any)