Abstract
OBJECTIVE: This study aims to examine the relationship between habitual nighttime sleep duration and anxiety symptoms in preschoolers, and to identify a potential sleep-health threshold for mental health promotion. METHODS: This cross-sectional study included 1589 participants from two public kindergartens. Parents reported habitual nighttime sleep duration using the Children's Sleep Habits Questionnaire (CSHQ) and anxiety symptoms using the Preschool Anxiety Scale (PAS). Initial non-parametric tests were supplemented with linear mixed-effects models (LMM) incorporating for fixed effects for sleep duration and covariates, with family cluster as random intercepts. RESULTS: Among the participants, the mean age was 4.58 ± 0.86 years, and 52.2% were male. Initial nonparametric analysis revealed significant overall differences in anxiety symptoms (PAS: H=8.503, P=0.014) and generalized anxiety (GAD: H=7.427, P=0.024) across nighttime sleep duration groups. Adjusted LMM showed preschoolers with ≤9 hours of nighttime sleep had significantly higher PAS total scores (β=3.13, 95% CI: 1.01~5.25, P=0.004) and elevated scores across multiple anxiety subdomains (physical injury fears, social phobia, and obsessive-compulsive symptoms; all P<0.05) compared to >10h sleepers. Although the overall GAD model was nonsignificant (P=0.056), these children showed elevated GAD subscale scores (β=0.60, 95% CI: 0.14~1.07, P=0.011) aligns with prior evidence. Sensitivity analyses using alternative nighttime sleep duration thresholds (8.5h, 9.5h) and weekday-specific data confirmed the robustness of these findings. CONCLUSION: Our data suggests that nighttime sleep duration of 9 hours is an approximate sleep-health indicator for preschool aged children. These findings reinforce the importance of prioritizing healthy sleep habits as part of early childhood wellness initiatives, including age-appropriate nighttime sleep duration.