title: Associations of endogenous melatonin and sleep-related factors with behavioral problems in preschool Japanese children.
abstract: OBJECTIVE
  We 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.
  
  
  METHODS
  Subjects 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.
  
  
  RESULTS
  After 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.
  
  
  CONCLUSIONS
  Sleep disturbance, later times of sleeping and waking up, and lower melatonin levels might be involved in the development of pediatric behavioral disorders.
authors.affiliation: Department of Epidemiology and Preventive Medicine, Gifu University Graduate School of Medicine, Gifu, Japan. dr_keiko@gifu-u.ac.jp
authors.forename: Keiko
authors.initials: K
authors.lastname: Wada
authors.forename: Kozue
authors.initials: K
authors.lastname: Nakamura
authors.forename: Yuya
authors.initials: Y
authors.lastname: Tamai
authors.forename: Michiko
authors.initials: M
authors.lastname: Tsuji
authors.forename: Kaori
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ando
authors.forename: Chisato
authors.initials: C
authors.lastname: Nagata
mesh_terms: D002648:Child; D002653:Child Behavior Disorders / Q000209:etiology*; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000172:deficiency / Q000652:urine; D011863:Radioimmunoassay; D012893:Sleep Wake Disorders / Q000150:complications*; D011795:Surveys and Questionnaires
chemical_list: C054513:6-sulfatoxymelatonin; D008550:Melatonin
keywords: Behavior; Child; Melatonin; Sleep