Associations of endogenous melatonin and sleep-related factors with behavioral problems in preschool Japanese children

PurposeWe aimed to investigate the associations of sleep disturbance and sleep time with behavioral problems and to assess whether endogenous melatonin was associated with sleep-related factors and behavioral problems.MethodsSubjects were 234 boys and 203 girls, aged 3–6 years, in a cross-sectional study in Japan in 2006. Information related to children's sleep disturbance, sleep time, and behavioral problems was obtained from parent-administered questionnaires. Children's behavioral problems were assessed by the Strengths and Difficulties Questionnaire. The 6-sulfatoxymelatonin levels in first-void morning urine were measured by radioimmunoassay.ResultsAfter multiple adjustments for covariates, children who often snore at night (P = .011), awake at night (P = .019), and looked tired in the daytime (P = .041) had a higher total difficulties score. Earlier time of waking (trend P = .021) and earlier time for bed (trend P = .014) were associated with a lower total difficulties score. Children with higher creatinine-corrected 6-sulfatoxymelatonin had lower total difficulties scores (trend P = .011). There were no associations between creatinine-corrected 6-sulfatoxymelatonin and sleep-related factors.ConclusionsSleep disturbance, later times of sleeping and waking up, and lower melatonin levels might be involved in the development of pediatric behavioral disorders.