narcolepsy
"Took my first dose Saturday night.  Wow! What a difference the next morning, I was wide awake, alert and hot to go to my work and my college lessons! As I write this I have been on Xyrem for about three months, and recently started having hand tremors occasionally.  I noticed that one other person ("Anonymous") mentioned shaking; once in awhile my tremors are strong.  Xyrem certainly has cured my severe narcolepsy, which began about a year ago without warning.  I am glad to see that several people have been on Xyrem for years without any adverse side effects, and no withdrawal symptoms when they stopped briefly. "