Variability of sleep and relations to body weight among first-year college students

Authors: NICHOLSON, LAURA - Loyola University; EGBERT, AMY - Loyola University; MORENO, JENNETTE - Children'S Nutrition Research Center (CNRC); BOHNERT, AMY - Loyola University

Submitted to: International Journal of Behavioral Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2020
Publication Date: 5/8/2020
Citation: Nicholson, L.M., Egbert, A.H., Moreno, J.P., Bohnert, A.M. 2020. Variability of sleep and relations to body weight among first-year college students. International Journal of Behavioral Medicine. https://doi.org/10.1007/s12529-020-09888-3.
DOI: https://doi.org/10.1007/s12529-020-09888-3

Interpretive Summary: Existing research suggests that greater variability in day-to-day sleep duration and sleep timing may increase risk for weight gain. College often marks a transition to a less consistent daily schedule, which may adversely impact sleep routines and further increase risk for weight gain. The current study is among the first to explore relations between nighttime sleep variability and daytime sleep (napping) and body weight among first-year college students. Using daily diary methods, 307 first-year college students (84.7% female) self-reported their sleep for seven days. Students' sleep varied over an hour on average across the week. Greater differences in day to day wake time and weekend versus weekend sleep duration were all associated with higher BMI, after accounting for the effects of gender, depressive symptoms, and sleep duration. Longer napping was also associated with higher BMI. Finally, greater sleep variability was reported by overweight and obese than healthy weight individuals. These findings suggest that sleep variability, particularly wake times and napping may be important modifiable sleep behaviors to investigate in future studies. More longitudinal research is needed to explore relations between multiple facets of sleep variability and weight gain, including possible mechanisms.

Technical Abstract: Existing research suggests that greater sleep variability may increase risk for weight gain. College often marks a transition to a less consistent daily schedule, which may adversely impact sleep routines and further increase risk for weight gain. The current study is among the first to explore relations between nighttime sleep variability and daytime sleep (napping) and body weight among first-year college students. Using daily diary methods, first-year college students (N=307; 84.7% female) self-reported their sleep for seven days. Several indices were created to capture sleep variability for reported bedtime, wake time, and sleep duration, including weekday versus weekend differences (WvW), day to day differences (D2D), and overall standard deviation (SD). Napping was also assessed. Based on body mass index (BMI), individuals were categorized as underweight, healthy weight, overweight, and obese. Across indices, students' sleep varied over an hour on average across the week. Hierarchical regressions revealed that greater differences in wake time D2D, wake time SD, and sleep duration WvW were all associated with higher BMI, after accounting for gender, depressive symptoms, and sleep duration. Longer napping was also associated with higher BMI, using the same covariates. Finally, greater sleep variability was reported by overweight and obese than healthy weight individuals. These findings suggest that sleep variability, particularly wake times and napping may be important modifiable sleep behaviors to investigate in future studies. More longitudinal research is needed to explore relations between multiple facets of sleep variability and weight gain, including possible mechanisms.