title: Sleep EEG evidence of sex differences in adolescent brain maturation.
abstract: OBJECTIVE
  The steep decline in slow-wave (delta) electroencephalogram (EEG) intensity across adolescence is a prominent feature of late brain maturation. As a first step in determining whether the adolescent delta decline is similar in both sexes, we compared cross-sectional sleep EEG data from 9- and 12-year-old boys and girls.
  
  
  METHODS
  All-night EEG recordings, 6 months apart, were conducted on each subject.
  
  
  METHODS
  EEG was recorded in the subjects' homes.
  
  
  METHODS
  Thirty-two 9-year-olds and 38 12-year-olds are enrolled in a 4-year longitudinal study of adolescent sleep. There are equal numbers of each sex in both age cohorts.
  
  
  METHODS
  N/A.
  
  
  METHODS
  Using ambulatory recorders, EEG was recorded in the subjects' homes on their normal sleep schedule. For each of the 2 semi-annual recording periods, data from the 10 subjects from each age-sex group with the cleanest (fewest artifacts) signals were selected for crosssectional comparisons of visual scoring and EEG variables. All artifact-free 20-second non-rapid eye movement epochs were analyzed with power spectral and period-amplitude analysis.
  
  
  RESULTS
  In the 12-year-old cohort, delta power per minute was 37% higher in boys than girls. The 9-year-old cohort showed no sex difference. A second recording 6 months later produced similar results.
  
  
  CONCLUSIONS
  These cross-sectional data indicate that girls begin the steep adolescent decline in slow-wave EEG earlier than boys. We hypothesize that this reflects an earlier onset of adolescent synaptic pruning in females.
authors.affiliation: Department of Psychiatry, University of California Davis Sleep Lab, 1712 Picasso Ave, Suite B, Davis, CA 95616, USA. igCampbell@ucdavis.edu
authors.forename: Ian G
authors.initials: IG
authors.lastname: Campbell
authors.forename: Nato
authors.initials: N
authors.lastname: Darchia
authors.forename: Wong Y
authors.initials: WY
authors.lastname: Khaw
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Higgins
authors.forename: Irwin
authors.initials: I
authors.lastname: Feinberg
mesh_terms: D000293:Adolescent; D001143:Arousal / Q000502:physiology; D001921:Brain / Q000254:growth & development*; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003700:Delta Rhythm; D004569:Electroencephalography; D004585:Electrooculography; D005260:Female; D006801:Humans; D008297:Male; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D011795:Surveys and Questionnaires