Background: This study tested if the timing of meals, physical activity, light exposure, and sleep cluster within individuals and are associated with body mass index (BMI) in a sample of free-living adults (N = 125). Methods: Data were collected between November 2015 and March 2016 at the University of California, San Diego, Children’s Hospital of Philadelphia, and Washington University in St Louis. Height and weight were measured, and BMI (kg/m2) was calculated. Sleep timing was estimated using actigraphy, and timing of meals, physical activity, and light exposure were self-reported using a smartphone application. General linear models estimated the mean BMI across time categories of behaviors, adjusting for covariates. A latent class analysis was used to identify patterns of timing variables that clustered within individuals and test for associations between identified patterns and BMI. Results: Later exposure to outdoor light was associated with a lower BMI (P trend < .01). The timing of other behaviors was not independently associated with BMI. The latent class analysis identified 2 distinct groups related to behavioral timing, reflecting an “early bird” and “night owl” phenotype. These phenotypes were not associated with BMI (P > .05). Conclusion: Timing of exposures to light, meals, sleep, and physical activity were not strongly associated with BMI in this sample.
P.J. and J.A.M. contributed equally as senior author. Marinac is with Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA; and Harvard T.H. Chan School of Public Health, Boston, MA. Marinac and Wang are with UC San Diego Moores Cancer Center, La Jolla, CA. Quante, Mariani, Weng, Redline, and Kaplan are with the Division of Sleep and Circadian Disorders, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA. Quante is also with the Department of Neonatology, University of Tübingen, Tübingen, Germany. Redline is also with Beth Israel Deaconess Medical Center, Boston, MA. Cespedes Feliciano is with the Division of Research, Kaiser Permanente Northern California, Oakland, CA. Hipp is with the Department of Parks, Recreation, and Tourism Management, NC State University, Raleigh, NC; and the Center for Geospatial Analytics, NC State University, Raleigh, NC. James is with the Division of Chronic Disease Research Across the Lifecourse (CoRAL), Department of Population Medicine, Harvard Pilgrim Health Care Institute, Harvard Medical School, Boston, MA; and the Departments of Environmental Health and Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA. Mitchell is with the Division of Gastroenterology, Hepatology and Nutrition, Children’s Hospital of Philadelphia, Philadelphia, PA; and the Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.