Comparison of visual analysis and automatic sleep stage scoring (Oxford Medilog 9000 System).

The Oxford Medilog 9000 System with Sleep Stager, a device for the mobile recording of sleep EEGs and automatic analyses of sleep, was tested with regard to its functional capacity, possible applications and reliability. Four all-night sleep records were evaluated visually and compared with the automatic analysis. Tendentially uniform differences were evident in two areas: the automatically scored sleep onset time was always shorter than the visually assessed time, and the automatic analysis consistently scored less REM than the visual assessment. There ought, therefore, to be fundamental reasons for these two situations. The advantages of the mobile EEG recording and automatic analysis of sleep are that considerably less time and personnel are involved, and that the results are readily available, which means that one can perform considerably more investigations. The differences from the visual evaluation can be attributed to the system and are thus calculable, provided that a few necessary improvements are made with regard to reliability.