Drink the coffee black. No sugar, no calories! Lol.
Re: caffeine pills. I can drink coffee no problem. And stay awake all over the clock. Completely irrespective of coffee or any other thing. Anyhow, I had a job that had very limited access to "facilities". Sooo, I picked up some caffeine pills so that this would not be an issue (see also: headache avertment). They made me feel like kakashalanga. Not at first, but say it were overnight, at the end, where I'd normally just be a bit buzzed with bizarro energy, I'd feel bizzaro buzzed and sh***y. (Which of course leads to the question why did I take them?! It was an experiment. Even cut in half had this effect.) So anyway, YMMV.

So... coffee, yeah, maybe, depends how it affects you personally. For me, as much as I love it, it would be a joke of ineffectiveness. So I'd go with the answer:

Moving around. Physically. That's what helps me. And NO, I don't feel like doing so at the time, hahaha! But if I do it, it helps a lot. A brisk walk around the block, jumping into some cleaning. I remember clearly one time when meds really zonked me into serious sleepy bear mode. I was trapped at work and couldn't move around much. Was essentially melting over the counters. Could.not.stay.awake. Yeah, it can be pretty intense.

Maybe scheduling in some quick activity between study blocks?