The main symptom in this condition is excessive daytime sleepiness. An affected child or young people can fall asleep at awkward times (eg at school, during meals or during an activity). They can sleep for a few seconds or minutes and occasionally for longer periods such as an hour or so.
In addition to excessive daytime sleepiness, narcolepsy is associated with:
- cataplexy - this is a sudden loss of voluntary muscle tone usually triggered by emotions, laughter being the most common
- hypnagogic/hypnopompic hallucinations - these are highly vivid hallucinations, often happening at the onset of sleep (hypnagogic) or on waking up (hypnopompic)
- sleep paralysis - these are brief episodes of inability to move at the beginning or end of sleep.
Automatic behaviour (where individuals carry actions with a certain amount of purpose but don't remember doing so) is another common occurrence during the day. Presentation of narcolepsy symptoms can vary, which can make this condition difficult to diagnose and often with a significant delay.