narcolepsy
"Provigil is different for everyone. Personally, I can begin to feel it working about 30 to 45 min. I take it as soon as I get out of bed so it's on an empty stomach. I eat after I get dressed so by the time I'm making breakfast I feel like I received a caffeine boost that will last about 8-10 hours.

If I'm having a hard time waking up, I have been known to take the medication and take a 15 min nap. I set my alarm  for 15-20 min. When I wake up again,  my head is clear, I feel refreshed and ready to burst out of bed. "