Time in bed and Low Body Mass Index (BMI) among adolescents in China
Lam, L. T. (2008). Time in bed and low Body Mass Index (BMI) among adolescents in China. Sleep and Hypnosis, 10(1).
Study Objective: To investigate the association between time in bed and low Body Mass Index (BMI <18.5 kg/m2) among adolescents.
Methods: This is a population school-based health survey utilising a two-stage random cluster sampling design. One thousand two hundred and sixty seven (n=1267) subjects aged 13 to17 years participated in the study. They were recruited from the total population of adolescents attending high school in the Nanning, the capital city of the Guangxi Province, China. Time in bed was measured by self-reported time to bed and rise in a normal school week. Body Mass Index was calculated from body weight and height assessed by health professionals.
Results: There was a significant dose-response relationship between time in bed and low BMI. After adjusting for the potential confounding factors, young people who were in bed for a shorter period of time (<7>hours) had a reduced risk of about 30% for low BMI (OR= 0.76, 95%C.I.=0.58-0.99) compared to those who were in bed 7-8 hours. No significant increase in risk were found for those who slept for longer than 8 hours (OR=1.42, 95%C.I.=0.93-2.19) when compared with the controls.
Conclusions: Time in bed is associated with low BMI among adolescents suggesting a potential link to chronic energy deficiency (CED). It would be prudent for clinicians to include the assessment of potential CED in the evaluation and diagnosis of sleeprelated problems among adolescents.