title: Electroencephalographic sleep profiles and hypothalamic-pituitary-adrenocortical (HPA)-activity in kindergarten children: early indication of poor sleep quality associated with increased cortisol secretion.
abstract: OBJECTIVE
  In children, objective data carried out from sleep EEG monitoring are scarce. Furthermore, results associating the hypothalamic-pituitary-adrenocortical (HPA)-activity with sleep EEG measurements in children are missing. Therefore, our study aimed to investigate in preschool-children the association between sleep patterns and endocrine activity. Furthermore, children's behavioral/emotional difficulties and competences were assessed in order to correlate psychological strain with sleep measures.
  
  
  METHODS
  Sixty-seven kindergarten children (35 boys and 32 girls) aged 5.34 underwent EEG-monitoring for one night. For baseline HPA-activity assessment, saliva samples were collected immediately after awakening, whereas saliva samples before, while and after a psychological challenge were used to assess the HPA-activity under stress conditions.
  
  
  RESULTS
  Compared to girls, boys showed significantly more REM sleep time. After cluster analysis, children labeled as 'poor' sleepers (n=27; 40,30%) showed significantly increased morning cortisol values, as compared to 'good' sleepers (n=22; 32,83%). Furthermore, increased cortisol AUC values under stress conditions were significantly associated with an elevated number of awakenings after sleep onset, and more sleep time in stages 1 and 2. In addition, an increased sleep efficiency was significantly correlated with self-reported emotional/behavioral difficulties, i.e. with low degrees of impulsivity (r=-.31; p<.05) and lower degrees of social inhibition and peer victimiziation (r=-.26, p<.05).
  
  
  CONCLUSIONS
  Our results underlined that already in preschool years, associations between objectively examined unfavorable sleep patterns, increased HPA-system activity and more difficult behavioral and psychosocial dimensions may be observed.
authors.affiliation: Psychiatric Out-Patient Department, University Hospital Basel, Switzerland. christine.haselbach@upkbs.ch
authors.forename: Martin
authors.initials: M
authors.lastname: Hatzinger
authors.forename: Serge
authors.initials: S
authors.lastname: Brand
authors.forename: Sonja
authors.initials: S
authors.lastname: Perren
authors.forename: Stephanie
authors.initials: S
authors.lastname: Stadelmann
authors.forename: Agnes
authors.initials: A
authors.lastname: von Wyl
authors.forename: Kai
authors.initials: K
authors.lastname: von Klitzing
authors.forename: Edith
authors.initials: E
authors.lastname: Holsboer-Trachsler
mesh_terms: D002653:Child Behavior Disorders / Q000175:diagnosis / Q000453:epidemiology; D002656:Child Day Care Centers / Q000706:statistics & numerical data*; D002675:Child, Preschool; D004569:Electroencephalography; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D008297:Male; D010913:Pituitary-Adrenal System / Q000378:metabolism*; D017286:Polysomnography; D011584:Psychology; D012463:Saliva / Q000737:chemistry; D012720:Severity of Illness Index; D012892:Sleep Deprivation / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism*; D012894:Sleep Stages / Q000502:physiology; D014851:Wakefulness
chemical_list: D006854:Hydrocortisone