narcolepsy
"I was diagnosed with Nacolepsy about a year and half ago and started taking Nuvigil.  I began with a 150mg dose once a day and the first couple weeks were great.  Like some of the other reviews colors were brighter, I was more focused and felt better than I ever remember feeling.  After a couple of months on that dose I started to have midday sleeping spells, where I could not keep my eyes open, even when in the middle of complicated work functions.  I would literally fall asleep while typing, waking to find the same letter across the page.  I spoke to my Doctor and the dose was upped to 250mg once a day.  I went throught the same effects as when I first started taking the medication.  Again the effects have slowly worn off."