Easy, I just don’t really sleep. I drink coffee but I have been drinking it for a while now so it doesn’t keep me up (more like makes me functional lol). When I study in my apartment I take “study breaks” by studying for a non-science class (most of my studying is for science classes) like German or Indo. Euro. Folktales, I then read and do problems for another few hours, watch the same thing I read up on, on Khan Academy, wash dishes or clean my apartment, hit the books some more, maybe cook (I have coffee with every meal) and I also have decaf peppermint tea, it wakes me up (for some reason) but without the caffeine. So I would suggest study breaks, napping in between for a half hour (IF naps work for you and you don’t over sleep or end up feeling sleepier after a nap), walking around between studying, switching up subjects when you get bored, talking to yourself (explaining why certain things occur aloud) , watching Khan Academy videos and putting a little caffeine in the mix (Not super recommended because I have a high caffeine tolerance [especially for my 98 pounds] so I’m not sure how you’d react to it).