The associations among objectively estimated sleep and obesity indicators in elementary schoolchildren.

OBJECTIVE: A negative linear association between sleep duration and obesity in children has been reported, but this has been predominantly based on subjective estimates of sleep duration and only one indicator of obesity. This cross-sectional study aimed to examine the relationships among objectively measured sleep parameters and a range of obesity indicators in schoolchildren.

PATIENTS/METHODS: Baseline data were obtained from 335 elementary schoolchildren (aged 7-12 years) recruited to the study. Five indicators of obesity were determined and two global cut-off points (WHO and International Obesity Task Force) were used to define overweight/obesity. Participants wore wrist actigraphy devices (N = 264) for seven consecutive days/nights to objectively estimate six sleep features.

RESULTS: Average weekday sleep duration was 7.6 ± 0.7 h and 42.1% of the participants were overweight/obese. After adjustment, those achieving <8 h of sleep had an increased body mass index z-score (β = 0.88, p < 0.001), waist circumference (β = 6.49, p < 0.001), body fat percentage (β = 5.17, p < 0.001), and fat mass (kg) (β = 3.23, p < 0.001) compared to those sleeping ≥8 h. Based on two standardized cut-off points for overweight/obesity, sleeping <8 h was associated with an increased risk of obesity (odds ratio (OR) = 3.75, 95% confidence interval (CI): 1.56-9.05; OR = 4.79 95% CI: 2.11-10.90).

CONCLUSION: Sleep insufficiency, in addition to other lifestyle factors, is likely to play a role in childhood obesity. Lifestyle interventions should include advice regarding sleep improvement with promotion of other healthy lifestyle behaviors to tackle childhood obesity, a serious global public health problem.