Artifact processing in computerized analysis of sleep EEG - A review

Quantitative analysis of sleep EEG data can provide valuable additional inf ormation in sleep research. However, analysis of data contaminated by artif acts can lead to spurious results. Thus, the first step in realizing an aut omatic sleep analysis system is the implementation of a reliable and valid artifact processing strategy. This strategy should include: (1) high-qualit y recording techniques in order to minimize the occurrence of avoidable art ifacts (e.g. technical artifacts); (2) artifact minimization procedures in order to minimize the loss of data by estimating the contribution of differ ent artifacts in the EEG recordings, thus allowing the calculation of the ' corrected' EEG (e.g. ocular and ECG interference), and finally (3) artifact identification procedures in order to define epochs contaminated by remain ing artifacts (e.g. movement and muscle artifacts). Therefore, after a shor t description of the types of artifacts in the sleep EEG and some typical e xamples obtained in different sleep stages, artifact minimization and ident ification procedures will be reviewed.