title: Regional Patterns of Elevated Alpha and High-Frequency Electroencephalographic Activity during Nonrapid Eye Movement Sleep in Chronic Insomnia: A Pilot Study.
abstract: OBJECTIVE
  To examine nonrapid eye movement (NREM) sleep in insomnia using high-density electroencephalography (EEG).
  
  
  METHODS
  All-night sleep recordings with 256 channel high-density EEG were analyzed for 8 insomnia subjects (5 females) and 8 sex and age-matched controls without sleep complaints. Spectral analyses were conducted using unpaired t-tests and topographical differences between groups were assessed using statistical non-parametric mapping. Five minute segments of deep NREM sleep were further analyzed using sLORETA cortical source imaging.
  
  
  RESULTS
  The initial topographic analysis of all-night NREM sleep EEG revealed that insomnia subjects had more high-frequency EEG activity (> 16 Hz) compared to good sleeping controls and that the difference between groups was widespread across the scalp. In addition, the analysis also showed that there was a more circumscribed difference in theta (4-8 Hz) and alpha (8-12 Hz) power bands between groups. When deep NREM sleep (N3) was examined separately, the high-frequency difference between groups diminished, whereas the higher regional alpha activity in insomnia subjects persisted. Source imaging analysis demonstrated that sensory and sensorimotor cortical areas consistently exhibited elevated levels of alpha activity during deep NREM sleep in insomnia subjects relative to good sleeping controls.
  
  
  CONCLUSIONS
  These results suggest that even during the deepest stage of sleep, sensory and sensorimotor areas in insomnia subjects may still be relatively active compared to control subjects and to the rest of the sleeping brain.
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.
authors.forename: Brady A
authors.initials: BA
authors.lastname: Riedner
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.|University of Arizona, Department of Psychology, Tucson, AZ.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Goldstein
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.
authors.forename: David T
authors.initials: DT
authors.lastname: Plante
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.
authors.forename: Meredith E
authors.initials: ME
authors.lastname: Rumble
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.
authors.forename: Fabio
authors.initials: F
authors.lastname: Ferrarelli
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.
authors.forename: Giulio
authors.initials: G
authors.lastname: Tononi
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI.
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Benca
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D001921:Brain / Q000502:physiology / Q000503:physiopathology*; D016022:Case-Control Studies; D002908:Chronic Disease; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D010865:Pilot Projects; D017286:Polysomnography; D066191:Sensorimotor Cortex / Q000503:physiopathology; D012890:Sleep / Q000502:physiology; D007319:Sleep Initiation and Maintenance Disorders / Q000503:physiopathology*; D013826:Theta Rhythm
keywords: alpha-delta sleep; high-density EEG; local sleep; neuroimaging; source modeling