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Bedtime associated with BMI in adolescents, adults

A later average bedtime was associated with an increase in body mass index, according to data published in Sleep.

The association indicates that bedtime may be a target for weight management, Lauren D. Asarnow, MA, department of psychology, University of California, Berkeley, and colleagues reported.

The researchers used data from the National Longitudinal Study of Adolescent Health (Add Health). The data for Add Health were collected in four waves; waves I and II were collected when participants were in grades 7 to 12 and waves III and IV were collected when participants were aged 18 to 32 years. This study only included data from waves II, III and IV, which included data from 132 schools and 3,342 participants.

Lauren D. Asarnow

Participants self-reported sleep and circadian measures. BMI was calculated from weight and height measurements. Asarnow and colleagues used hierarchical linear models in a two-level random intercept and slopes model to evaluate the association between the two.

Results showed that later average workday bedtime was associated with an increase in BMI (b = 0.048; standard error = 0.017; t = 2.80; df = 3,238; P < .05).

"Later average bedtime during the workweek in the years from adolescence to adulthood was associated with an increase in BMI across that period," Asarnow and colleagues wrote. "These results remained significant even after controlling for sleep duration, baseline BMI, demographic characteristics, screen time, exercise frequency, and fast-food consumption. Our results highlight adolescent bedtimes as a potential target for weight management concurrently and in the transition to adulthood." – by Chelsea Frajerman Pardes

Disclosures: The authors report no relevant financial disclosures.