title: Sleep-disordered breathing in children with metabolic syndrome: the role of leptin and sympathetic nervous system activity and the effect of continuous positive airway pressure.
abstract: OBJECTIVE
  The purpose of this work was to determine whether, in children with metabolic syndrome and sleep-disordered breathing, metabolic markers separate them from children with metabolic syndrome without sleep-disordered breathing and whether treatment of sleep-disordered breathing with continuous positive airway pressure is associated with an improvement in metabolic derangement.
  
  
  METHODS
  Subjects aged 7 to 19 years old with metabolic syndrome and a positive validated sleep questionnaire were recruited. Subjects underwent overnight polysomnography, during which sympathetic nervous system activity was assessed via 8-hourly measurements of norepinephrine and epinephrine, together with leptin. The next morning, a fasting 3-hour oral glucose-tolerance test was performed to calculate whole-body insulin sensitivity. A fasting lipid panel interleukin 6, adiponectin, and C-reactive protein levels were also measured. Children with sleep-disordered breathing were placed on continuous positive airway pressure for 3 months and studied again. Sleep-disordered breathing and no sleep-disordered breathing groups were compared by using Fisher's exact test and t test for independent samples with analysis of covariance to adjust for age and BMI.
  
  
  RESULTS
  Of 34 children studied, 25 had sleep-disordered breathing (apnea-hypopnea index: >1.5). Mean hourly norepinephrine and leptin levels were higher in the group with sleep-disordered breathing compared with the group without sleep-disordered breathing (P < .005), with no difference in whole-body insulin sensitivity. Eleven subjects with sleep-disordered breathing completed 3 months of nightly continuous positive airway pressure treatment. In the follow-up study, mean hourly leptin levels were significantly lower than in the initial study, with no change in BMI z score or other measurements.
  
  
  CONCLUSIONS
  Our findings support the hypothesis that sleep-disordered breathing in children with metabolic syndrome is associated with increased sympathetic nervous system activity and leptin levels but not worsening of insulin resistance. Treatment of sleep-disordered breathing with continuous positive airway pressure led to a significant decrease in leptin levels.
authors.affiliation: Yale University School of Medicine, Department of Pediatrics, Section of Respiratory Medicine, 333 Cedar St, Fitkin 510, New Haven, CT 06520, USA.
authors.forename: Neal
authors.initials: N
authors.lastname: Nakra
authors.forename: Sumit
authors.initials: S
authors.lastname: Bhargava
authors.forename: James
authors.initials: J
authors.lastname: Dzuira
authors.forename: Sonia
authors.initials: S
authors.lastname: Caprio
authors.forename: Alia
authors.initials: A
authors.lastname: Bazzy-Asaad