Narcolepsy is a medical condition that makes people suddenly fall asleep at unexpected times, even when they're trying to stay awake. Someone with narcolepsy might be talking with friends, eating lunch, or sitting in class when their brain basically flips a switch and they fall asleep without warning. These sleep attacks can last from a few seconds to several minutes.

People with narcolepsy often feel extremely tired during the day no matter how much they slept the night before. Their brains have trouble regulating the normal cycle between sleeping and waking that most people experience. It's like their sleep switch is faulty: it can turn on when it shouldn't, and it doesn't always work properly at night either, so they might have trouble sleeping well even when they're trying to.

Some people with narcolepsy also experience something called cataplexy, where strong emotions like laughter or excitement cause their muscles to suddenly go weak or limp. They remain conscious but might drop what they're holding or even fall down.

Narcolepsy is caused by the brain not producing enough of a chemical that helps control wakefulness. Doctors can treat it with medication and by helping patients develop good sleep schedules, though there's currently no cure.