"In addition to excessive daytime sleepiness people with narcolepsy dream very frequently, and a lot more than the average person would, they also may be associated with symptoms that are kind of unusual. Like cataplexy which is a transient loss of muscle function. It's precipitated by a strong emotion. So if there's a funny joke or surprise or fear or terror, all of a sudden that person may lose some of their muscle function. It may last for moments or even minutes. Most of the time it affects the head and the neck and the shoulders. So it could be something very subtle, such as the face becoming Slack or the inability to speak clearly, or the eyes shutting. But sometimes the whole body can be affected and somebody can actually fall to the ground with loss of muscle function of their legs. Their knees may buckle. They may actually collapse.
They can feel it coming, but they can't do anything about it. And they're completely conscious while this happens. They're aware of everything going on, but sometimes they may have double vision and they can't talk, but they know what's going on around them. It's just out of control. Sometimes narcoleptics actually avoid comedy clubs or surprise parties because they don't want that sudden emotion. They may avoid scary movies because they know they'll have a fright and they'll lose control. Cataplexy is not prevalent in everybody with narcolepsy, but it's certainly a very distinctive thing. And if one has that aspect of cataplexy, the diagnosis of dark narcolepsy can be made. So excessive daytime sleepiness is the most common symptom and cataplexy is the most interesting and exotic symptom."