Sleeping quality, sleeping habits and their association of BMI in children in southern China

Lichun Fan^1*Yue Lei¹Chuican Huang¹Weijia Wu¹Qing Luo¹Wenting Cao²Junwei Xie¹Hongai Li¹

• ¹Hainan Women and Children's Medical Center, Haikou, China
• ²Hainan Medical University, Haikou, Hainan Province, China

Objectives: This study analyzed the effects of sleep quality along with sleep duration and bedtime on BMI in children aged 3-12 years, and explored their role in the occurrence and development of obesity in children. Methods: This study conducted a cross-section study on children in 18 cities and counties of Hainan Province. The Children's Sleep Habits Questionnaire (CSHQ) along with a parents-report children's features survey were used to assess children's sleep quality and habits, among other factors. Results: The multi-variable analysis results showed that bedtime was positively correlated with childhood overweight or obesity. However, the relationship between the outcome and sleep duration in children remains uncertain. The results of the additive interaction model indicated that sleep duration between 9-11 hours or 11 hours and above, combined with poor sleep quality or earlier bedtime (before 21:00), served as protective factors against children’s overweight or obesity. Conversely, children with adequate sleep duration but later bedtime had a higher risk of being overweight or obese (OR: 1.214, 95%CI: 1.069-1.379). Children with sleep duration less than 9 hours, regardless of bedtime, had an increased risk of adverse outcomes (OR: 1.394, 95%CI: 1.022-1.901; OR: 1.268, 95%CI: 1.039-1.548). Conclusion: Short sleep duration (<9 hours) and late bedtime (>22:00) independently and synergistically increase obesity risk, while adherence to recommended sleep patterns (9–11 hours, bedtime before 21:00) offers protection. Nonlinear analyses confirm a heightened obesity risk below 9 hours of sleep, with partial attenuation beyond 11 hours. Poor sleep quality paradoxically associates with lower obesity risk.