High Frequency EEG Activity during Sleep: Characteristics in Schizophrenia and Depression

Janet L. Tekell, Robert Hoffmann, William Hendrickse, Robert W. Greene, A. John Rush, Roseanne Armitage

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


Previous studies indicate that high frequency power (>20Hz) in the electroencephalogram (EEG) are associated with feature binding and attention. It has been hypothesized that hallucinations and perceptual abnormalities might be linked to irregularities in fast frequency activity. This study examines the power and distribution of high frequency activity (HFA) during sleep in healthy control subjects and unmedicated patients with schizophrenia and depression. This is a post-hoc analysis of an archival database collected under identical conditions. Groups were compared using multivariate analyses of covariance (MANCOVA) using group frequency by stage analysis. A multiple regression analyzed the association between HFA power and clinical symptoms. Schizophrenic (SZ) and major depressive disorder (MDD) patients showed significantly greater high frequency (HF) power than healthy controls (HC) in all sleep stages (p<0.0001). SZs also exhibited significantly greater HF power than MDD patients in all sleep stages except wakefulness (W) (p<0.05). In all groups, gamma (35–45Hz) power was greater in W, decreased during slow wave sleep (SWS) and decreased further during rapid eye movement (REM). Beta 2 (20–35 Hz) power was greater in W and REM than in SWS. Only positive symptoms exhibited an association with HF power. Elevated HFA during sleep in unmedicated patients with SZ and MDD is associated with positive symptoms of illness. It is not clear how HFA would change in relation to clinical improvement, and further study is needed to clarify the association of HFA to the state/trait characteristics of SZ and MDD.

Original languageEnglish (US)
Pages (from-to)25-35
Number of pages11
JournalClinical EEG and Neuroscience
Issue number1
StatePublished - Jan 2005


  • Beta Activity
  • Electroencephalography
  • Gamma Activity
  • Key Words
  • Major Depressive Disorder
  • Schizophrenia
  • Sleep

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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