Sleep EEG evidence of sex differences in adolescent brain maturation

Sleep. 2005 May;28(5):637-43. doi: 10.1093/sleep/28.5.637.


Study objectives: 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.

Design: All-night EEG recordings, 6 months apart, were conducted on each subject.

Setting: EEG was recorded in the subjects' homes.

Participants: 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.

Interventions: N/A.

Measurements: 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.

Conclusion: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Arousal / physiology
  • Brain / growth & development*
  • Child
  • Cohort Studies
  • Cross-Sectional Studies
  • Delta Rhythm
  • Electroencephalography*
  • Electrooculography
  • Female
  • Humans
  • Male
  • Sleep / physiology*
  • Sleep Stages / physiology
  • Surveys and Questionnaires