Is there a safe stimulant to use? Coffee does NOT work on me.?

Coffee does not work on me, and I have a lot of work to do because I go to a good school, and there is a very rigorous academic curriculum along with super competitive peers. I have wrestled with staying up late but it has proven highly unproductive. I tried all that time management crap and sorry, I just have a crapload of work to do, so don't suggest it. Sorry for sounding like a jerk, but I am dang tired and need help. staying up, that is... O_o