Peer-reviewed article
Associations of chronotype with daytime functioning and obesity in elementary school children.
Qinye Zhu, Hiroo Wada, Yuito Ueda, Yoshihito Kameda, Hiroshi Nakano et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined how children's sleep timing (chronotype) relates to their daytime functioning and weight in 1,893 elementary school children in Tokyo, Japan. Children with later sleep timing experienced more morning sleepiness, emotional and behavioral problems, and higher obesity risk compared to those with earlier sleep timing. Children with earlier sleep timing showed better attention and fewer attention lapses in morning tests. The findings suggest that sleep timing significantly influences children's daily functioning and health.
Key points
- Each hour delay in sleep timing was associated with higher BMI z-scores and nearly doubled the odds of obesity for late chronotype children
- Later chronotype children reported greater morning sleepiness and daytime sleepiness compared to early chronotype children
- Later chronotype was associated with more emotional and behavioral problems as reported by parents
- Early chronotype children showed faster response speed and fewer attention lapses on morning vigilance tests
- Study included 1,893 children aged 6-12 years from six elementary schools in Tokyo
Limitations
The study is cross-sectional, so it cannot establish whether later chronotype causes these problems or whether these conditions influence sleep timing. The findings are from Tokyo, Japan, and may not generalize to other populations with different school schedules or daylight patterns.
Abstract
OBJECTIVE: Evidence linking chronotype to daytime functioning and obesity in elementary school-aged children remains limited. This study examined the associations between chronotype and sleepiness, emotional/behavioral problems, obesity, and morning vigilant attention. METHODS: Children from six elementary schools in Tokyo, Japan, were recruited. Chronotype was indexed by the sleep-corrected midpoint of sleep on free days (MSFsc). Outcomes included obesity, child-reported morning sleepiness, parent-reported daytime sleepiness, and emotional/behavioral problems assessed using the Strengths and Difficulties Questionnaire. Morning vigilant attention was assessed using a 3-min Psychomotor Vigilance Test (PVT) on two consecutive mornings. Non-PVT outcomes were analyzed using generalized linear and logistic regression models, and repeated PVT measures were analyzed using mixed-effects models. RESULTS: The sample included 1893 children (mean age ± SD, 9.0 ± 1.7 years; age range, 6-12 years; 51.2% boys). Each 1-h delay in MSFsc was associated with a higher BMI z-score (β = 0.099, q = 0.01), greater morning sleepiness (β = 0.268, q < 0.001), greater daytime sleepiness (β = 0.073, q < 0.001), and more emotional/behavioral problems (q < 0.05). Compared with intermediate chronotype, late chronotype showed higher estimated odds of obesity (OR = 1.92, q = 0.05), whereas early chronotype showed faster response speed (β = 0.068, p = 0.04) and fewer lapses (β = -0.145, p = 0.02) in PVT analyses (n = 1580). CONCLUSION: Later chronotype was associated with greater sleepiness, more emotional/behavioral problems, and higher BMI z-scores. Early chronotype was associated with better morning vigilant attention than intermediate chronotype.