narcolepsy
"I have been taking Xyrem for 8 years now, and only wish I had started sooner. The first 32 years of my life were spent suffering from undiagnosed narcolepsy and constantly being exhausted during the day. After finally taking myself to a sleep specialist I discovered that, even though I would sleep at night, I was never getting any recooperative sleep.  They started me on Xyrem (and methylphenidate er during the day) and I feel so much better now.  The cataplexy and sleep paralysis are gone!  I sometimes wonder if I am building up a tolerance to it because it may take me an hour to fall asleep, but I love this stuff!  I haven't had many side effects, except if I'm still awake after an hour and a half - then it's pretty miserable and nauseous."