narcolepsy
"I have been taking nuvigil since 2012 started on provigil built a tolerance against it in 2 months. I take 250 mg a day but I split the pill and take each half at specific times usually  between 6-9 am the other at 3pm to 6pm (depends when I took the first one) seems to help me stay awake a little more that way. It lasts for about 1-2 hours on me with each half."