narcolepsy
"I've been back on Nuvigil since the end of 2013.  I had taken it in 2010, but had to stop due to cost.  The results have been wonderful.  No more falling asleep in meetings or while sitting and talking to people.  I can even watch entire movies now without dozing off!  The only downside, like others have mentioned, is that it wears off in the evening.  I usually take it around 7am, but by 9:00pm, I'm dozing again, which isn't really that bad.  The cost is annoying too.  I have great insurance, but it is still $75 a month."