narcolepsy
"I was recently diagnosed with narcolepsy and started on Provigil.  I started with 100 mg in the morning and then 100 or 150 mg in the afternoon.  The first few days I was a little dizzy at first, a little nauseous, lost my appetite, had a mild headache every night (ibuprofen took care of that), and tense jaw/neck muscles.  It was working great, but once I started classes (i.e., inactivity), I was falling asleep sometimes before my noon dose, and everyday around 6pm or 8pm.  So, my doctor upped it to 200 in the morning and 200 after noon.  For all 3 days of it, I was awake, only crashing around 8pm, but I was having problems with my memory and concentration. Just switched to Ritalin. "