Журнал расстройств сна и терапии
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Later Bedtime is Associated with Greater Daily Energy Intake and Screen Time in Obese Adolescents Independent of Sleep Duration

Kristi B Adamo, Shanna Wilson, Kevin Belanger and Jean-Philippe Chaput

Objective: To examine if sleep timing (combination of bedtime and wake up time) is associated with energy intake and physical activity/sedentary behaviour in obese adolescents.

Methods: Participants included in this cross-sectional examination were 26 (13 females) obese volunteers (BMI ≥ 95^th percentile) with a mean age of 13.6 ± 0.5 years and valid data on self-reported sleep, food intake (dietary record), physical activity and sedentary time (accelerometer), screen time (self-reported), and anthropometry (BMI). We categorized participants as “late sleepers” (midpoint of sleep >3:30 a.m., n=13) and participants as “normal sleepers” (midpoint of sleep ≤ 2:30 a.m., n=13).

Results: As expected, wake-up time and bedtime were different between sleep timing groups (p<0.01); however, total sleep duration was the same (9.23 ± 1.14 vs. 9.16 ± 1.28 hours for normal and late sleepers, respectively, p=0.88). There was no significant BMI difference between late sleepers and normal sleepers. Total daily caloric intake was 27% higher in late sleepers (425 kcal) compared to normal sleepers (p=0.04). Using a linear regression model in the whole sample we observed that later sleep timing was associated with greater total caloric intake, independent of age, sex, BMI, moderate-to-vigorous physical activity (MVPA) and sleep duration (β=368.6, p=0.01). No association was found between sleep timing and MVPA or sedentary time. However, later sleep timing was related to greater screen time, independent of age, sex, BMI and sleep duration (β=105.7, p<0.01).

Conclusion: The present study is the first to report that later bedtime is associated with greater caloric intake and screen time in obese adolescents independent of total sleep duration.