A paper by Dr. Kristi Adamo, Shanna Wilson, Kevin Belanger and Dr. Jean-Philippe Chaput, “Later Bedtime is Associated with Greater Daily Energy Intake and Screen Time in Obese Adolescents Independent of Sleep Duration,” was recently published in the Journal of Sleep Disorders and Therapy. Citation details are below along with a summary of the paper.
Adamo KB, Wilson S, Belanger K, Chaput JP. Later Bedtime is Associated with Greater Daily Energy Intake and Screen Time in Obese Adolescents Independent of Sleep Duration. J Sleep Disorders Ther 2013, 2:4.
ABSTRACT: 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 ≥ 95th 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.