Following a baseline night recording, 9 narcoleptic subjects and 9 sex and age-matched control subjects were maintained on 16 hours of diurnal sleep deprivation. Thereafter subjects were submitted to a 32 hour bed rest protocol in a sound-light attenuated room. The EEG was recorded and processed using a Fast Fourier Transform. Narcoleptic patients did not differ from control subjects in total sleep time over the whole time-span. An ultradian tendency to sleep seems to be predominant in narcoleptic patients and evidence of a strong basic rest activity cycle is shown. The coupling between the homeostatic process of sleep regulation and an ultradian drive to sleep would explain the peculiar 4 hour distribution pattern of SWA in narcoleptic patients.