Narcolepsy

Few days ago, while having a conversation with my friend, she told me about her Univeristy mate suffering from narcolepsy. I knew nothing about this disorder. My friend explained me that the girl tends to fall asleep during lessons. Actually, she said that whenever she sees her, she always sleeps. I was truly shocked. After, I read some information on the Internet about this disorder and it appears that the reasons of narcolepsy are not known for the moment but probably, they are related to the phase of sleeping called REM( rapid eye movement). First symptoms of narcolepsy appear during puberty or even over the age of 20! People struggling with it have difficulties in falling asleep at night. The disorder is incurable.
My friend also told me that the girl is frequently robbed for instance while sleeping on the tram :(
I think that we are really lucky not to struggle with this life-limiting disorder.