Sleep Duration and Body Mass Index in 5–9 Aged Korean Children

Objective: Since sleep duration has been suggested to play an important role in the development of obesity in children, the risk factors for insufficient sleep have received increasing attention. The aim of this study was to investigate the sleep duration and compare it with obesity with sleep duration in children aged 5–9 years.Methods: This cross-sectional study was conducted using Dietary Screening Test which is a parent-reported questionnaire administered to Korean children aged 5–9 years between January 2021 and July 2022. Data including sleep duration and bedtime were obtained. Body mass index (BMI) was categorized into the following four groups according to the age-specific BMI criteria: underweight, normal weight, overweight, and obesity.Results: Altogether, 15,543 out of the 22,055 participants, comprising 7,605 (48.9%) boys and 7,938 (51.1%) girls aged 5–9 years, were finally included in the analysis. The proportion of participants above the 85th percentile was 24.3%. The average sleep duration was 9.40±0.88 h. A comparison of sleep duration between the four BMI groups showed a significant difference in sleep duration at 5, 6, and 7 years of age (p<0.05). The bedtime for children aged 5 to 9 years was 21.69±0.75 h. There was a significant difference in bedtime at 9 years of age among the four BMI groups (p<0.05).Conclusion: In this study of Korean children, the obesity group had the shortest sleep duration at the age of 5–7 years and latest bedtime at age 9. These results may contribute to a better understanding of interventions to achieve sufficient sleep duration and prevent obesity in children.