Patent No. 4354505 Method of and apparatus for testing and indicating relaxation state of a human subject

 

Patent No. 4354505 

Method of and apparatus for testing and indicating relaxation state of a human subject (Shiga, Oct 19, 1982)

Abstract

In a self-training biofeedback system, a physiological signal representing the state of relaxation of a person using the system is applied to a time counter to generate a binary count output representing the relaxation period. A visual indicator connected to the time counter provides the self trained person with a quick display of the measured time period so he can gauge the depth of his relaxation.

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BACKGROUND OF THE INVENTION

The present invention relates to self-training biofeedback systems for indicating the mental condition of a person to assist him in bringing his mind into a state of relaxation.

It is well known that human mental activity can be measured in terms of electrical activity of the brain as represented by the brain waves, or in terms of electrical potential changes measured by electromyographic method, or potential changes at the surface of the skin or temperature at the skin surface. It is also known that these physiological phenomena can be used to control the autonomous nerve system of the person or as a means for rehabilitation of incapacitated people. More specifically, when a human subject is in a relaxed state of mind, the predominant brain waves are the so-called alpha waves and the muscle potential decreases to a low level with an increase in the electrical resistance and temperature of his skin. Conversely, when the subject in a strained or highly excited state, brain waves called beta waves, are predominant and the muscle potential increases with a decrease in skin electrical resistance and temperature.

Thus, an indication of such physiological signals could serve as a guide to lead the person into a relaxed state of mind. This kind of mind control is called "biofeedback" and the apparatus used for such therapy is called a biofeedback system.

Most prior art biofeedback systems, however, are only capable of indicating the presence of a state of relaxation by means of an audible or visual indicator, so that the person using the system remains unaware of the interval while the desired state is maintained. One approach would be to employ a costly recording apparatus comprising stylus which traces the detected signal on a recording sheet, which is unsatisfactory for household use.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved self-training biofeedback system for household use which measures the length of time during which the user is in a state of relaxation and gives a visual indication of the measured time on a real time basis.

The state of relaxation is usually attained by the act of meditation. It is usually difficult for laymen to attain a state of complete relaxation. The general tendency is for laymen to repeat the process of going into a state of incomplete relaxation and returning therefrom to an unrelaxed state during the initial stage of meditation. The biofeedback system of the invention provides the user with a quick indication of the persistence of the relaxation state. This allows the user to gauge the depth of relaxation and encourage him to make further attempts to reach the point where his mental and physical stresses are completely liberated.

According to the invention, various modes of time measurement are available. In one embodiment a total count value of relaxation periods is measured and simultaneously indicated. Since the length of sustained relaxation is an indication of the degree of his attainment, each count value of the successively occurring relaxations is indicated by updating the previous count. Thus, in another embodiment the count value is cleared when the person using the system subsequently enters the state of relaxation. In this embodiment, minimum and maximum time counts may also be detected for separate indications to allow the user to compare his attained results. In further embodiments, a ratio of the total time period to a given interval of time during which he has performed meditation is derived.