I'm prescribed Modafinil(Provigil) for sleep apnea. I take 200mg first thing every morning. It is a fantastic drug, and a life saver for me. You do not build up a tolerance to it, contrary to what some have said. I've taken it for 3 years straight and it works the exact same everyday. I have tried the generic stuff from India before my doc prescribed me Provigil, and there is no comparison. The stuff from India works a little, but nothing like USA Provigil. It makes me very alert, and very focused for 12-15 hours, no jitters, no change in heart rate, no nothing. The only side effects I get are gas, urine smells exactly like the pill itself, and if not hydrated it can cause a slight headache. This drug will make you focus on whatever you are doing at the time. It is great for retaining information, I can read something once and retain all of it. Most of the docs I work with use it daily, or some use Adderall. It is superior to Adderall. If you like to feel euphoria, adderall will give that, but it seems you build a tolerance to Adderall where Provigil you don't.