DISCRIMINATION AMONG STATES OF CONSCIOUSNESS USING EEG SPECTRA

EEG recordings were made during waking (W) and the five sleep stages (REM, 1, 2, 3, and 4) on thirteen young adult males. For each stage, one‐minute sections of the pa ietal EEG trace were digitized and subjected to Fourier analysis. The resulting spectral intensities were divided into five frequency bands; delta, theta, alpha, sigma, and beta. Linear discriminators for all six stages were calculated using stepwise multiple regression. The overall percent agreement with visual scoring was very poor, ranging from zero for stage 3 to 91% for stage 4. Linear discrimination between pairs of stages yielded slightly better results, but stages 1 and REM were indistinguishable. Delta is the best overall discriminator, increasing significantly through stages W, 1, 2, 3, and 4. Sigma is unique to sleep and is highest for stage 2. Theta is unimportant and beta plays no role at all. Spectral analysis of the parietal EEG lead is not sufficient to differentiate among the six states of consciousness studied here. The use of detectors for such phasic events as eye movement and K‐complexes might aid sleep stage discrimination considerably. Copyright © 1969, Wiley Blackwell. All rights reserved