Sigma (12-15 Hz) and Delta (0.3-3 Hz) EEG oscillate reciprocally within NREM sleep

S. Uchida, T. Maloney, J. D. March, R. Azari, I. Feinberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

108 Citations (Scopus)


Sleep EEG in the sigma and delta frequency bands was subjected to spectral analysis in 8 normal young adults. In each subject, power density of sigma and delta oscillated reciprocally during NREM sleep, confirming an observation made initially with period/amplitude analysis. In REM sleep, power density for both frequency bands was at its lowest levels. Correlation coefficients between power density of delta vs. 1/sigma for all artifact-free 20-s epochs of NREM sleep/night were highly significant for each subject. These results show that cyclic oscillation of EEG within sleep is not limited to delta frequencies. The reciprocal relation of sigma to delta holds implications for the EEG mechanisms of NREM sleep. This dynamic pattern may also prove useful for sleep stage scoring and for a finer empirical analysis of sleep in psychiatric and neurological disorders.

Original languageEnglish
Pages (from-to)93-96
Number of pages4
JournalBrain Research Bulletin
Issue number1
Publication statusPublished - 1991
Externally publishedYes


  • Cyclic patterns
  • Delta
  • EEG
  • Frequency analysis
  • Sigma
  • Sleep
  • Sleep spindles

ASJC Scopus subject areas

  • Neuroscience(all)


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