SPECTRAL ANALYSIS OF EEG OF DOMINANT AND NON-DOMINANT ALPHA SUBJECTS DURING WAKING AND SLEEPING

EEG spectral analysis of the left parietal lead (P3) was carried out on nine high alpha and four low alpha subjects. A 0.2 c/sec resolution interval was used on analysis periods of 1 min. The most prominent feature of the spectra was a delta peak at about 1 c/sec consistently present for all subjects during waking as well as sleeping. The intensity of this delta peak increased monotinically from waking through sleep stages 1, 2, 3 and 4 with stage REM intensity being equal to stage 1 intensity. All subjects had a sigma peak at about 13 c/sec during sleep stage 2, and a majority had a similar peak in stages 3 and 4. The average spectra show a sigma in all sleep stages, but none during waking. There were no consistent theta or beta peaks during waking or any stage of sleep. The high alpha group showed an alpha peak in waking at about 10 c/sec which decreased to about 9 c/sec during stage 1 and stage REM. During waking and all stages of sleep, they generally had a higher intensity and higher variability than the low alpha subjects for all frequencies of the spectrum. High alpha subjects had more frequency peaks during stages I and REM. The two groups have very similar spectra in sleep stages 2, 3 and 4. The waking intensities of the delta, theta and alpha frequency bands have significant positive correlations with their respective intensities during sleep. Waking intensity of the alpha band never correlated with delta intensity during waking or sleeping. These results favor the hypothesis of constant frequency generators for delta and sigma with an increase in energy during sleep; but they also fit the hypothesis of an alpha generator which decreases in frequency and energy during sleep. The single, best discriminator of waking and the sleep stages was delta. Alpha and sigma intensities add to the discrimination. However, stage 1 and REM have very similar spectral profiles for all subjects. For the low alpha subjects, waking, stage 1, and stage REM have spectra that are almost indistinguishable. © 1969.