Reliability of rapid clinical staging of all night sleep EEG

The recording of all night sleep EEGs on a portable cassette recorder, and the rapid visual staging of the sleep records at 20 times real time, represent innovations in sleep research methodology. The reliability of sleep stager percentages obtained in this way is examined in this article. In the first of two studies, all night sleep records for six individuals were each staged twice by each of two qualified electroencephalographers. Inter-rater and intra-rater reliability assessed by intraclass correlation methods was modest, requiring the averaging of results from two judges to reach acceptable levels. Following consistency training, the two electroencephalographers staged all night sleep records for six additional subjects. Acceptable reliability was achieved in measurement of stages 2, 3, 4 and REM, although difficulty in reliably distinguishing stage 1 from the awake stage persisted. On the basis of these results, rapidly paced visual interpretation of sleep records at 20 times real time is recommended as a feasible way of meeting demands imposed by innovations in the technology of recording sleep EEGs.