- Incidence: 0.70 cases per 100,000 person-years
- Peak incidence: 20-30 years
- Sex ratio: 1:1
- Excessive daytime sleepiness (80%)
- Lethargy (70%): Some patients with narcolepsy will have chronic daily sleepiness as the sole symptom
- Limb weakness (unilateral) (40%)
- Hallucinations (30%): Hypnagogic hallucinations are vivid visual, tactile, or auditory hallucinations that can occur when a patient is falling asleep.
- Syncope (20%): Whilst narcolepsy doesn't cause a loss of consciousness, patients may describe themselves as having episodes of 'collapse'.