Abstract
INTRODUCTION: Social jetlag (SJL), the discrepancy in sleep timing between weekdays and weekends, is associated with higher BMI and cardiometabolic risk and is common in young adults. We examined whether chronic SJL impacts weight gain in young adults participating in a weight gain prevention trial. METHODS: Young adults (n = 599, age 18-35; BMI: 21.0-30.9 kg/m(2)) completed assessments at 0, 4, 12, and 24 months. Multilevel mixed growth models were used to examine (1) associations between demographics and longitudinal SJL and (2) longitudinal SJL as a predictor of weight change and cardiometabolic outcomes. SJL was assessed as a continuous and clinically-significant dichotomous (< vs. ≥2 h) variable. RESULTS: 38% of participants had clinically-significant SJL at ≥ 1 timepoints (Baseline M ± SD = 1.3±0.89). Younger (b=-0.05, p < 0.001), female (b = 0.18, p = 0.037) and Black (compared to White, b = 0.23, p = 0.045) participants were more likely to have greater SJL. Individuals with high SJL (≥ 2 h; between-person effect) were more likely to have greater weight gain over 2 years (b = 0.05, p = 0.028). High SJL did not affect the rate of change in waist circumference or cardiometabolic markers over time. CONCLUSIONS: High SJL is associated with greater weight gain over time. Reducing SJL may positively impact weight status in young adults.