Narcolepsy, or Gélineau disease, from the name of the French doctor (1828-1906) who described it for the first time, is a sleep disorder characterised by daytime drowsiness and uncontrollable sleeping fits. Other symptoms can add to the clinical picture:
- cataplexy episodes, sudden and momentary loss of muscle tone, often emotion-triggered, characterising type 1 narcolepsy;
- hypnagogic hallucinations, sort of waking dream, whether the patient is conscious or not;
- sleep paralysis, waking but unable to move or speak, which may accompany hallucinations;
- tendency to obesity;
- restless sleep…
Narcolepsy is a rare disease, which affects one person in 2,500 in Europe. It occurs most often during adolescence, however a large proportion of patients remain undiagnosed and untreated despite the highly debilitating nature of the disease.
The diagnosis is initially based on evaluation of drowsiness, measured most often using the Epworth sleepiness scale, and in the case of type 1 narcolepsy, the highly revealing presence of cataplexy attacks.
Several tests can confirm the diagnosis: the polysomnography (electroencephalogram recording of a night’s sleep), which shows direct abnormal transitions from waking in REM-sleep, the multiple sleep latency test (MSLT) which confirms mean sleep latency of just 3 to 4 minutes, or even cerebrospinal fluid testing, which reveals very low orexin levels.