narcolepsy
"Nuvigil works really well. The effectiveness does slightly wears off after several consecutive days with the dose, but taking a day or two off of the medication has restored effectiveness for me. The only side effect I've experienced in the last month and a half is headaches (infrequently, at that). Be wary of mixing caffeine with Nuvigil. In my case, caffeine increases palpitation-like symptoms, increases jitteriness, and has even provoked hallucinations more than once."