A new Harvard Medical School study looked at the connection between when teens go to bed and the weight they gain, and found that night owl girls have more weight problems.
Sleep experts call your sleep schedule a “chronotype.” This new research found that for adolescent girls, but not boys, bigger waistlines and greater fat mass were associated with being an evening chronotype. An individual with an evening chronotype is typically called a night owl.
The research says the weight gain is independent of sleep duration and other lifestyle factors.
This observational study of 804 adolescents (418 girls and 386 boys, with an average age 13) from eastern Massachusetts included data from wrist monitors, questionnaires and body measurements. Chronotype was measured based on a scale with higher scores indicating evening versus morning preferences for adolescents; social jet lag was the difference in sleep midpoint in hours from midnight on weekends (free days) versus weekdays (school days) with higher values meaning that sleep timing shifted later on free days. There were no associations with a cardiometabolic risk score.
The findings suggest that obesity prevention efforts should consider regular patterns of sleep and wake times in addition to healthy diets.