Associations of diarised sleep onset time, period and duration with total and central adiposity in a biethnic sample of young children: the Born in Bradford observational cohort study

ObjectivesTo investigate associations of parent-reported sleep characteristics with adiposity levels in a biethnic sample of young children.DesignA cross-sectional observational study.SettingThe Born in Bradford 1000 study, UK.ParticipantsChildren aged approximately 18 months (n=209; 40.2% South Asian; 59.8% white) and 36months (n=162; 40.7% South Asian; 59.3% white).Primary and secondary outcome measuresChildren's body mass index (BMI) z-score, sum of two-skinfolds (triceps and subscapular) and waist circumference. Adjusted regression was used to quantify associations of sleep parameters with adiposity stratified by ethnicity and age group. The results are beta coefficients (95% CIs) and unless otherwise stated represent the difference in outcomes for every 1-hour difference in sleep parameters.ResultsThe average sleep onset time was markedly later in South Asian (21:2668min) than white children (19:41 +/- 48min). Later sleep onset was associated with lower BMI z-score (-0.3 (-0.5 to -0.0)) and sum of two-skinfolds (-1.5 mm (-2.8 mm to -0.2mm)) in white children aged 18months and higher BMI z-score in South Asian children aged 36months (0.3 (0.0-0.5)). Longer sleep duration on weekends than weekdays was associated with higher BMI z-score (0.4 (0.1-0.8)) and waist circumference (1.2 cm (0.3-2.2cm)) in South Asian children aged 18months, and later sleep onset on weekends than weekdays was associated with larger sum of two-skinfolds (1.7 mm (0.3-3.1mm)) and waist circumference (1.8 cm (0.6-2.9cm)). Going to sleep >= 20min later on weekends than weekdays was associated with lower waist circumference in white children aged 18months (-1.7 cm (-3.2 cm to -0.1cm)).ConclusionsSleep timing is associated with total and central adiposity in young children but associations differ by age group and ethnicity. Sleep onset times and regular sleep schedules may be important for obesity prevention.

Automated summary

The study aimed to investigate the associations between parent-reported sleep characteristics and adiposity levels in young children in a biethnic sample. The results showed that sleep timing is associated with total and central adiposity, but the associations vary by age group and ethnicity. It suggests that sleep onset times and regular sleep schedules may be important for obesity prevention.