Test tomorrow, lets study hard

as always I could never get to study in advance, although it is of utmost importance to the final only hours before I intend to do, so to fill my caffeine and no sleep, tomorrow I will have a difficult exam, and Wednesday I will have another the same difficulty.
So if someone can give me some recommendation on how to do for not sleeping, that is not just coffee, because I causes diarrhea after several cups, I would appreciate ittoo.
Hopefully everything goes well.

coffe, coffe, coffe