Delayed bedtime on non‐school days associates with higher weight and waist circumference in children: Cross‐sectional and longitudinal analyses with Mendelian randomisation

Mar 14, 2023Journal of sleep research

Later bedtimes on days off are linked to higher body weight and waist size in children

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗OA ↗

Abstract

Every 0.5-hour delay in bedtime on non-school nights is associated with a 0.048 increase in body mass index z-score (BMIz).

Children with later bedtimes on non-school nights show higher BMIz and waist-to-height ratios (WtHr).
A discrepancy in bedtimes between school and non-school nights correlates with increased adiposity.
Every 2-hour delay in bedtime at age 11 years corresponds with a 0.6 cm increase in waist circumference.
Longitudinal data suggest that later bedtimes predict higher WtHr over a 2.5-year follow-up.
Mendelian randomisation analysis indicates that higher BMIz does not cause delays in bedtimes.

AI simplified

Sleep duration has been linked with obesity in population-based studies. Less is known about bedtimes and, especially, if discrepancy between bedtimes on school and non-school days associate with adiposity in children. The associations of self-reported bedtimes with the body mass index z-score (BMIz) and waist-to-height ratio (WtHr) were examined among children with a mean (SD) age of 11.2 (0.85) years in cross-sectional (n = 10,245) and longitudinal (n = 5085) study settings. The causal relationship of whether BMIz contributes to bedtimes, was further examined in a subset of 1064 participants by exploiting Mendelian randomisation (MR). After adjusting for sleep duration and other confounders, every 0.5 h later bedtime on non-school nights and a delay in bedtime in non-school nights compared with school nights associated with 0.048 (95% CI 0.027; 0.069) and 0.08 (95% CI 0.056; 0.105) higher BMIz as well as 0.001 (95% CI 0; 0.002) and 0.004 (95% CI 0.003; 0.005) with higher WtHr, respectively. Moreover, every 0.5-h delay in bedtime in non-school nights compared with school nights associated with 0.001 (95% CI 0; 0.002) greater increase in WtHr in the 2.5 years follow-up. Thus, a 2-h delay in bedtime at the age of 11 years corresponds with a 0.6 cm increase in waist circumference. The MR analysis did not indicate an opposite causal relationship: higher BMIz was not causing delayed bedtimes. Later bedtime on non-school days and discrepancy in bedtimes associated with increased BMIz and WtHr, while longitudinally these predicted higher WtHr, independently of sleep duration. Promoting early bedtimes, especially on weekends, should be considered in obesity prevention among school-aged children.

Full Text

Full text is available at the source.

View full text (PDF) ↗View full text (XML) ↗View full text ↗

Delayed bedtime on non‐school days associates with higher weight and waist circumference in children: Cross‐sectional and longitudinal analyses with Mendelian randomisation

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief