Automated sleep scoring: a comparative reliability study of two algorithms.

In the present study, deterministic and stochastic sleep staging (DSS and SSS) methods were compared with expert visual analysis in order to provide reliability estimates under strict conditions of comparison. Thirty polygraphic records (15 controls, 15 patients) have been investigated, including artefacts and doubtful periods. Average agreement rates of both methods compared to expert visual scoring were very similar, although a few specifics occasionally appeared for partial sleep stages. The comparison of more than 40,000 sleep decisions (on 20 sec epochs) yielded 75% absolute reliability for normal controls and 70% for pathological cases. However, if the agreement rate obtained for routine visual scoring (82%) in our sleep laboratory is considered as satisfactory, our system is then 90% satisfactory. Finally, complementary aspects outlined in the two automatic scoring systems suggested the development of a unique algorithm on the basis of these methods. Keeping in mind the size of the test sample and the strict procedure of comparison, the two automated staging systems described in this study can be used with reasonable confidence for large scale investigations of sleep in man.