What is it?
Narcolepsy is a disorder that makes you less able to control when you want to sleep or when you want to be awake. The perhaps best known symptom is having periods of excessive daytime sleepiness – people with narcolepsy often become very tired or even fall asleep for a few minutes in inappropriate situations during the day. Many sufferers also have periods of sudden muscle strength loss.
Narcolepsy is quite common, but it is relatively little known and often misdiagnosed. It is thought to occur in about 1 in 2000 people.
What causes it?
The exact cause of narcolepsy is not known, but genetics as well as certain infectious diseases play a role.
What happens during it?
REM is a phase of sleep, and we often think of it as the phase in which we see vivid dreams. Normally REM only happens after we have been asleep for a while, but people with narcolepsy tend to go into the REM phase straight away. This seems to happen because the REM sleep is inadequately controlled, and the nerve cells that normally initiate the REM phase do so sometimes even when you’re wide awake even though they are only supposed to do this when you have been asleep for some time.
There are neurons called hypocretin neurons in our brain whose job it is to maintain wakefulness. There is some evidence suggesting that narcolepsy happens when these neurons start to die, and because for obvious reasons they cannot maintain wakefulness in the way they are supposed to, the threshold for going into REM sleep becomes lower and this starts to happen accidentally.
The hypocretin neurons seem to die because the immune system of our body kills them. This can happen if you get infected with a microbe whose surface proteins are too much like the surface proteins of your own cells. Your immune system does not normally react to your own cells, but if it has fought off this kind of microbe it could be that it has classified that surface protein as “something to destroy”, and when it encounters a similar surface protein on your own cell, it kills that too. This could be why narcolepsy is associated with certain types of infectious diseases.
How can it be treated?
Narcolepsy cannot be cured, but life with it can be made a lot easier. Some medications can be helpful, and having regular naps is also often recommended.
Sources: https://en.wikipedia.org/wiki/Narcolepsy, http://emedicine.medscape.com/article/1188433-overview?pa=M1iaBTZJCzTjQDPEFa3qj3t5WrXz2gxnUKQfcsfZa6yO4TJ41iRGFAC9KwhCVIXFVrJxKJt4DRD8mxYr6kYfOw%3D%3D#a3, https://en.wikipedia.org/wiki/Rapid_eye_movement_sleep