Automatic analysis of sleep records with static charge sensitive bed.

An automatic analysis of movements detected by the static charge sensitive bed (SCSB) was developed for the study of sleep and breathing disturbances (apnoeas) during sleep. Three signals on separate channels are analysed: one relating to body movements, one to respiratory movements and one to movements of the heart (ballistocardiogram). The analysis can be made on-line or from tape recordings. With a portable microcomputer the records and analyses can be carried out at home or on the ward without any professional personnel. The system can be preset to start and to end recording automatically. The subject just has to lie down. The automatic analysis of body movements on the basis of their amplitude and duration yields criteria for scoring of sleep into 'wakefulness,' 'quiet sleep' and 'active sleep.' A simple hypnogram and the statistics on the durations and proportions of these stages are printed. Simultaneous SCSB and polygraphic records were made on healthy subjects. Comparison of the two types of sleep scoring showed that the results agreed during 81% of the time. The amplitudes of the movements detected on the 3 channels are integrated in epochs and the results of this analysis are represented in a compressed graphic form which allows easy visualization of the overnight records. The pattern of 'respiratory movements' reveals whether the breathing has been regular, irregular or periodic.