A COMPUTERIZED METHOD FOR DETECTING EPISODES OF WAKEFULNESS DURING SLEEP BASED ON THE ALPHA-SLOW-WAVE INDEX (ASI)

A method for the automatic detection of episodes of wakefulness during sleep is presented. The algorithm is based on the evaluation of the a lpha slow-wave index (ASI), a measure that has been developed to detec t fluctuations of vigilance in daytime pharmaco-electroencephalogram s tudies. Its application to sleep data was validated with polysomnograp hic recordings from 16 elderly insomniacs and 16 young healthy subject s. The rate of agreement between the computerized procedure and the vi sual scoring of wakefulness was 94.0% for the insomniacs and 96.9% for the healthy subjects. The decision criterion used by the computer all owed the definition of a subject-adapted threshold for the detection o f wake episodes. The method opens new perspectives for the automatic a nalysis of continuous 24-hour sleep-wake recordings.