Abstract
Twenty one healthy adults performed a series of physiological and psychological tasks in a set order for designated periods from 9 a.m. to 5 p.m.. Their EEG responses were recorded continuously by the EEG telemetering which permitted the subject to act freely. In particular, an attempt was made to grasp the entirety of the waking state by comparing A.M. and P.M. data. Namely, alpha, theta, and beta 1 wave frequencies were isolated by analysis and their fluctuations from A.M. to P.M. were compared.
The results can be summerized as follows:
1) It was established that alpha wave levels reflected the general excitability level of the brain during waking hours.
2) Although the basic brain activity level was maintained, alpha, theta and beta 1 wave clearly tended to decrease in the afternoon.
3) Hypothesizing the existence of a standard energy range due to the consistency of the brain activity level, the author arrived at the following A.M. and P.M. integral values for each wave type. The integral values with 95% confidence are : alpha band component, A.M. 21.5±1.6mm, P.M. 18.6±1.4mm, theta band component, A.M. 22.2±2.2mm, P.M. 18.5±1.7mm, and beta 1 band component, A.M. 14.4±1.3 mm, P.M. 12.8±1.5 mm.
4) A chronogram was made by measuring the average frequency at 30 minutes intervals from 9 a.m. to 5p.m.. It was a gently U-shaped curve and the turning point was at approximately 1 p.m..
