I started at 5mg and ended up at 10mg. I could barely stay awake for the first 2-3 months while on it, but it was worth the benefits. 10mg seemed to be enough so I didn't ever go up to the full 20mg prescribed, but I was also afraid of getting any sleepier than I already was.

I agree with wi_fighter - get a 2nd opinion. People go to a doctor for information, not for a guessing game.