Hi,
I think Provigil is an individual thing. For example, I've heard of some people who can only take one 100mg a day, and that keeps them awake all day, and even some of them have to take 50mg.
And then there's me.... I take 200mg in the morning, and 100mg in mid afternoon, and fall into bed like a rock at 10pm. It does Not make me gittery like coffee does, thank goodness, cause that would be horrible. I drink coffee,and the mixture still doesn't make me gittery, and I'm very caffiene sensitive. Again, we're all snowflakes, same disease, different reactions. It's so weird.
Provigil is often prescribed for MS patients too. For those who only take it once in a while, that's great, but I'll tell you, I can't go with out it, or I'd probably be in a coma. It has made a huge difference in my life.