An on-line automated sleep-wake classification system for laboratory animals

A computerized sleep-wake classification program is presented that is capable of classifying sleep-wake states on-line in four animals simultaneously. Every 10 s the classification algorithm assigns sleep-wake states on the basis of the power spectrum of an EEG signal and the standard deviation of an EMG signal. The system was developed specifically for long- term circadian rhythm experiments and can run uninterrupted for an unlimited period of time. To validate the system a total of 5760 sleep-wake epochs from 4 rats was classified both visually and by computer. The results show a good agreement between visual and computer automated (kappa = 0.770) sleep wake scoring. Therefore, the presented sleep wake classification system can be regarded as a reliable and time saving alternative for visual scoring in sleep research.