I posted this elsewhere, but it fits under this heading, as well:
I have debilitating fatigue due to MS and have tried everything - Provigil, Amantadine, Adderall, Ritalin - the works. While Provigil helped for some time while I was still working, that was many years ago and its effectiveness eventually petered out. At the time, I was taking a very large dose in accordance to doctor's orders, and my side effects (heart palpitations, increased rate of speech, crashing, etc.