Apparently, it is legal to import prescription only drugs for personal use, provided they are not controlled substances.
I've taken adrafinil, which is metabolised into the body into modafinil. It is considered safer, less side effects, and is cheaper. It didn't interfere with my sleep patterns at all, but it did stop me feeling tired, made me feel more alert, without making me feel jittery or anything. I also felt in a good mood, but that may just have been because I wasn't tired like usual hehe.