One of my students has some great advice founded on real-world experience: "Find out how much sleep you need and make sure you get it, every single night. Staying up to study longer while sacrificing sleep will, in my humble opinion, come back to bite you."
The only thing I'd add is that you also have to stay physically well, so you should also eat well, get exercise, and do enough of the things that make you happy to stay happy.
Doing well at something as demanding as law school requires you to be at your physical and mental best. I've run four marathons and plan to run more. You don't train for a marathon by running as far and as fast as you can as much as you can. You have to pace your training, and you have to pace your racing. If you don't, you'll blow up. One year I was running too much and I ended up with a bad stress fracture and couldn't run the marathon. One year a good friend went out too fast and at the halfway mark of the marathon collapsed and required hospitalization. My very best race ever was one in which I ran the second half of the race one second faster than the first half. Pace is everything. Burn out now, and you'll pay later. Cram everything into your head and show up in class or the exam exhausted and you'll make a fool of yourself.
So see those movies. Go to those parties. Don't drink yourself into unconsciousness. Get outside.And study, and study a lot, but don't sacrifice yourself to studying.