In the present study, using an automatic method to discriminate the stages of sleep-wakefulness, 180 control recordings on 15 chronically implanted cats were examined. In addition to a quantitative analysis, some aspects of the sleep-wakefulness architecture were considered, especially the nature and the distribution of the sleep phases that lead to paradoxical sleep (normal sequences) or to wakefulness (abortive sequences). Taken together, these features allow the definition of a ‘control profile’ which could be useful for the better characterization of drug effects.