Computer analysis of polysomnographic data

Polysomnogram measures electroencephalogram (EEG), electrooculogram (EOG) and chin electromyogram (EMG) to monitor ever-changing brain state during sleep. Polysomnigraphic records are usually scored visually according to Rechtschaffen and Kales' manual. However, scoring more than 1400 pages of record is very time consuming. Therefore, automated scorer has been awaited. However, when a computer makes a hypnogram, it uses a lot of parameters, such as alpha rhythm, sleep spindles, sleep delta waves, rapid eye movements or tonic chin EMG levels. Continuous across night patterns of these parameters provide more important and detailed physiological information than that provided by hypnogram. In this article, the author reviewed analysis methods for EEG, EOG and EMG and discussed the importance of examining continuous across night patterns of sleep parameters.