A new method of EEG analysis and its application to the study of sleep.

Abstract

Summarya) In the course of our polygraphic study of sleep, a new method of EEG analysis was developed. As the result of a simple modification of the ordinary Walter type frequency analyser. we succeeded in obtaining a compact and easily observable record showing the long time variation of the integrated values of each band respectively.b) The application of this method to the study of sleep EEG opened a new aspect.1. The most remarkable feature of this analysis is the undulatory fluctuation of relatively long time in the low frequency component (long undulatory fluctuation), especially in 1–2 cps band. In general, one sleep cycle is composed of a few of these undulatory fluctuations repeatedly appearing and the state of slight fluctuation mainly corresponding to the paradoxical phase. This long undulatory fluctuation corresponds to successive sleep phases in certain rule. The gradual change appearing at the time of a shift from the moderate phase to the deep phase is characteristic.2. Generally the crest of the highest of these undulatory fluctuations during successive sleep cycles is highest at the first cycle and tends to decrease toward morning. The increasing slope is steepest at the first cycle and gentler toward morning.3. During the ascending stage of this undulatory fluctuation the gross body movements are very few and in the other periods are relatively many. Most of the abrupt decreases of the integrated values of the low frequency band are accompanid by gross body movement.This report is dedicated to Professor Haruo Akimoto, Director of the Department of Neuropsychiatry, Faculty of Medicine, University of Tokyo, in commemoration of his sixtieth birthday.This study was carried out with the earnest cooperation of C. Sasaki, B.A. and N. Nagamura, M.A. We are much indebted to Mr. K. Akagi of San'ei Instrument Ltd. for the technical support.