Time in bed, sleep quality and associations with cardiometabolic markers in children:The Prevention and Incidence of Asthma and Mite Allergy birth cohort study

We investigated associations of time in bed and multiple sleep quality characteristics with cardiometabolic markers in children. Data from the prevention and incidence of asthma and mite allergy study, a population-based prospective birth-cohort study started in 1996-1997 in the Netherlands, were analysed. In total 1481 children aged 11-12years completed a questionnaire (including questions on sleep) and underwent a medical examination. We measured body mass index, waist circumference, total- and high-density lipoprotein cholesterol, blood pressure and glycated haemoglobin. Results showed that in girls, some sleep characteristics were related to anthropometrics (body mass index, waist circumference) and cholesterol. Girls who had a long time in bed (11-12.5h) had 0.16 lower body mass index z-score (95% confidence interval -0.31; -0.01) and 0.99cm smaller waist circumference (95% confidence interval -2.01; -0.13) compared with girls who spent 10-10.5h in bed. Girls who went to bed late and rose early had 0.16mm higher total cholesterol (95% confidence interval 0.01; 0.31) and 0.08mm higher high-density lipoprotein cholesterol (95% confidence interval 0.01; 0.14) than early to bed/early rise' girls. Girls with night-time awakenings had 0.14mm higher total cholesterol (95% confidence interval 0.03; 0.25) than girls without night-time awakenings. Girls who felt sleepy/tired 1day per week had 0.10mm lower high-density lipoprotein cholesterol (95% confidence interval -0.16; -0.04) and 0.17mm higher total cholesterol/high-density lipoprotein cholesterol ratio (95% confidence interval 0.02; 0.32) than girls who did not feel sleepy. No associations were found for boys. Sleep characteristics were not related to blood pressure and glycated haemoglobin, and effect sizes of the associations in girls were small. Therefore, we consider it premature to propose that improved sleep could reduce cardiovascular risk during childhood.