Automatic sleep-stage scoring apparatus

An automatic sleep-stage scoring apparatus comprises a filter unit, a segmentation unit, a multiscale permutation entropy (MPE) unit and a classification unit. The filter unit generates a filter signal according to an electroencephalography (EEG) signal or an electrooculogram (EOG) signal. The segmentation unit operates to generates a plurality of segmented signals according to the filter signal. The MPE unit, by the MPE operation, processes the segmented signals to generate a plurality of MPE values of each of the segmented signals. The classification unit, by the linear discriminant analysis, processes the MPE values so that each of the segmented signals corresponds to a sleep stage.