title: Sex differences in delta and alpha EEG activities in healthy older adults.
abstract: OBJECTIVE
  To examine sex effects on sleep stages and electroencephalogram (EEG) spectral power in older adults.
  
  
  METHODS
  Sleep was polygraphically recorded for 2 consecutive nights, and blood was sampled during the last 24 hours.
  
  
  METHODS
  The University of Chicago Clinical Research Center.
  
  
  METHODS
  Two groups of healthy nonobese older subjects: 10 men (59 +/- 2 years), and 10 postmenopausal women (63 +/- 2 years).
  
  
  METHODS
  N/A.
  
  
  RESULTS
  A spectral analysis of the EEG was performed in the delta and alpha bands. There were no sex differences in sleep stages. Blood sampling resulted in reductions of total sleep time, sleep maintenance, slow-wave sleep, and absolute delta activity that were all larger in women than in men. In absolute values, delta and alpha activities in non-rapid eye movement (NREM) and rapid eye movement (REM) sleep were higher in women than in men, but, for delta activity, the sex differences were larger in REM than in NREM sleep. In women, but not in men, absolute delta activity in REM was decreased during blood sampling and was strongly correlated with absolute delta activity in NREM. Delta activity in REM did not dissipate across the night in either group. When normalized for the activity in REM sleep, the sex difference in delta activity in NREM sleep was reversed, with lower activity in women.
  
  
  CONCLUSIONS
  Sex differences in sleep EEG variables are present in older adults. When normalized, delta activity in older women is lower than in older men, which may be more consistent with sex differences in subjective complaints, in fragility of sleep in the presence of environmental disturbances, and in the relationship to growth-hormone release.
authors.affiliation: Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Federica
authors.initials: F
authors.lastname: Latta
authors.forename: Rachel
authors.initials: R
authors.lastname: Leproult
authors.forename: Esra
authors.initials: E
authors.lastname: Tasali
authors.forename: Elisa
authors.initials: E
authors.lastname: Hofmann
authors.forename: Eve
authors.initials: E
authors.lastname: Van Cauter
mesh_terms: D000368:Aged; D000513:Alpha Rhythm; D003700:Delta Rhythm; D004569:Electroencephalography; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012737:Sex Factors; D012894:Sleep Stages / Q000502:physiology