Narcolepsy is a condition characterized by extreme daytime sleepiness. Many affected people also suffer from sudden but temporary muscle weakness, known as cataplexy. Narcolepsy is a primary hypersomnia as it is not caused by or associated with any other diseases, mental illnesses or psychological problems.

Narcolepsy affects between 1 in 2000 and 1 in 5000 people and only about 25% of affected people are actually correctly diagnosed. Often people are mistakenly diagnosed with psychiatric or emotional problems.