High frequency waking EEG: reflection of a slow ultradian rhythm in daytime arousal

Neuroreport. 2000 Jul 14;11(10):2223-7. doi: 10.1097/00001756-200007140-00032.


The ultradian dynamics of the human waking EEG was studied using a short visual fixation task repeated every 10 min throughout the daytime. The EEG spectra obtained from the tasks were assessed for time effect and ultradian periodicity. Fronto-central EEG high frequency powers (22.5-44.5 Hz) decreased at the time of the midafternoon vigilance dip (14.00-17.00 h) along with slight concomitant increases in parietal alpha (7.5-13.5 Hz) and delta (1-3 Hz) powers. A slow ultradian rhythm with a 3-4 h periodicity strongly modulated EEG power in all frequency bands between 1 and 44.5 Hz. The high frequency waking EEG may well reflect the activity of a brain arousal process underlying maintenance of the waking state probably throughout the 24 h cycle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activity Cycles / physiology*
  • Adult
  • Alpha Rhythm
  • Arousal / physiology*
  • Artifacts
  • Biological Clocks
  • Cerebral Cortex / physiology*
  • Delta Rhythm
  • Electroencephalography*
  • Electromyography
  • Electrooculography
  • Fixation, Ocular
  • Frontal Lobe / physiology
  • Humans
  • Male
  • Parietal Lobe / physiology
  • Wakefulness / physiology*