[Circadian and ultradian cycles in narcolepsy]

In narcolepsy, homeostatic process is preserved while sleep/wake circadian process is impaired. Other circadian components (body temperature, endocrine secretions, subjective sleepiness) are preserved. This circadian system weakness permits the occurrence of a very strong ultradian component, modulating sleep/wake rhythm. So, a 4 hour ultradian rhythmicity of Slow Wave Activity, and a 2 hour NREM/REM cycle longer than in normal subjects, has been evidenced in narcoleptic patients. These circadian and ultradian alterations can explain a major part of the narcoleptic symptoms.