Biofeedback of Skin Potential Level for Sleep Control

Skin Potential Level (SPL) on the palmar surface increases at the early stage of sleep and recovers with arousal. We applied the phenomenon to sleep control by using the biofeedback technique. Two ways of control are possible : inhibition and promotion of sleep. First, an SPL biofeedback system for doze suppression was constructed. In the system an alarm sound was issued to a subject when his SPL exceeded a certain threshold level. This doze alarm system was proved to operate well through a series of experiments. Second, a possibility for promotion of sleep was tested by feeding back the SPL of a subject to himself with auditory information. The surf sound was adopted as the feedback signal. Our SPL biofeedback system was effective for subjects who suffered from sleeplessness as well as for normal people. Such techniques will be applicable to a doze alarm system for drivers, to clinical therapy of sleep disorder, and so forth.