A microcomputer-based sleep stage analyzer.

A microcomputer-based sleep stage analysis system for laboratory use is described. Rapid spectral analysis of the electroencephalogram (EEG) is achieved through hardware; subsequent analysis, including determination of the relative power in user-defined EEG frequency bands is provided through software. A decision matrix, based on standard sleep state analysis criteria, enables these spectral data, in conjunction with integrated electromyogram (EMG) power, to determine sleep stages. The system has been configured here to quantify standard sleep stages, but the algorithm can also identify, and provide information about, EEG states which are not easily classified according to earlier criteria used for visual classification of polygraphic records. This low-cost, user-friendly system thus achieves flexible, quantitative analysis of EEG and EMG signals.