title: Is a 2-night polysomnographic study necessary in childhood sleep-related disordered breathing?
abstract: OBJECTIVE
  There are limited data on the night-to-night variability of childhood sleep-related disordered breathing (SDB). We aim to assess for the presence of first-night effect (FNE) and to examine whether a single-night sleep study is adequate in the assessment of childhood SDB.
  
  
  METHODS
  In a case-control study investigating whether obesity is a risk factor for childhood SDB, the night-to-night variability of sleep and respiratory variables were studied.
  
  
  METHODS
  Forty-six obese children from a pediatric obesity clinic and 44 age- and sex-matched normal weight control subjects from local schools.
  
  
  METHODS
  All subjects underwent two consecutive overnight polysomnographic studies. An obstructive apnea index (OAI) >/= 1/h was considered diagnostic of SDB.
  
  
  RESULTS
  The mean age of the children was 11.21 years (SD 2.21). Forty-four obese children and 43 control subjects completed the 2-night study. Based on the criterion of the worst OAI over the 2 nights, 13 subjects were found to have SDB, 12 subjects were primary snorers, and 62 were normal subjects. In all subjects, the sleep efficiency improved and sleep-onset latency was reduced on the second night. While there was a rebound of rapid eye movement sleep with the associated worsening of respiratory indexes (mainly accounted for by an increase in central apneas and hypopneas) evident in normal subjects, there was a significant improvement of respiratory disturbances in the SDB group on the second night. The first-night polysomnography would have correctly identified 84.6% of cases as defined by the criteria of the worst OAI over the 2 nights. All cases missed by the first-night study had only borderline OAI.
  
  
  CONCLUSIONS
  The phenomenon of FNE in children was well demonstrated in our study. We proposed that a single-night sleep study is adequate and more cost-effective in assessing for childhood SDB.
authors.affiliation: Department of Psychiatry, Shatin Hospital, Shatin, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Albert M
authors.initials: AM
authors.lastname: Li
authors.forename: Yun Kwok
authors.initials: YK
authors.lastname: Wing
authors.forename: Agnes
authors.initials: A
authors.lastname: Cheung
authors.forename: Dorothy
authors.initials: D
authors.lastname: Chan
authors.forename: Crover
authors.initials: C
authors.lastname: Ho
authors.forename: Stephen
authors.initials: S
authors.lastname: Hui
authors.forename: Tai Fai
authors.initials: TF
authors.lastname: Fok
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications / Q000503:physiopathology; D017286:Polysomnography; D012720:Severity of Illness Index; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D013997:Time Factors