hypersomnia
"I have been on this medicine for 7 years and cannot imagine life without it.  It doesn't seem to work for everyone, but is a lifesaver for me.  I had a headache for 3 days when I started it and lost my appetite for a week.  After that it was fine.  I can get by on 200mg if I need to, but feel tired still most of the day (but won't fall asleep unless I want to).   My usual dose is 300mg which keeps me alert and I can't even take a nap if I want to."