Two narcoleptic and 2 normal poodle or mixed poodle dogs were polygraphically monitored for 48 h with one narcoleptic and one normal monitored concurrently. Data were categorized by 15-sec epochs into wakefulness, light sleep, slow wave sleep, REM sleep, cataplexy (immobility preceded by wakefulness with partial or complete electromyographic quiescence and pronounced theta activity from subcortical leads), and atonia with no theta (15-30 sec periods like cataplexy but without theta). In narcoleptics we could see no gross differences between the polygraphic records of cataplexy and those of REM sleep; scoring distinctions between the two states depended on the antecedent state. Results indicated that narcoleptic dogs do not differ from normals with respect to percent of time spent in wakefulness (39.8% vs. 42.6%), light sleep (16.2% vs. 18.4%), or slow wave sleep (27.2% vs. 28.0%). Narcoleptic dogs spent slightly less time than normals in REM sleep (6.9% vs. 11.1%) and spend 9.1% and 0.8% of the recording time in cataplexy and atonia with no theta respectively. Normal dogs presented neither of these pathological states.