Narcolepsy

This is a disease characterised by excessive daytime sleepiness, sleep paralysis and visual hallucinations when falling asleep. The specific symptom is cataplexy: the sudden loss of muscle strength without a loss of consciousness after experiencing an emotion. It is a rare disease, which affects only about 20-60 people per 100,000 inhabitants. It is estimated that some 25,000 people have narcolepsy in Spain.

People with narcolepsy have lost the neurons in the brain that synthesise hypocretin, a neurotransmitter whose function is to prevent a person from falling asleep and entering REM sleep. There are drugs that are effective in improving drowsiness and others for cataplexy.