The first step to getting yourself to sleep is putting yourself in bed, I know it's obvious and stupid and sucks, but like, just lay down in bed and even if you're too stressed to sleep lay there and don't get back up until your alarm (maybe have a shitload of alarms though if you're like me and will get to sleep right before 9am and won't get up easily)

but yeah, stress-sleeping sucks. look at melatonin and vitamin D maybe. I have never listened to this advice personally, but they always say to get off the computer/any screen for a while before you go to sleep, and I'm sure it helps.

but yeah, just get up for class and go even if you just fall asleep through the whole class. It'll help you get more on a sleep schedule and stuff like that and also I'm like 90% sure you still learn stuff by sleeping in class. If the prof gets mad about you sleeping just be honest and apologize but don't stop going to class.

um, yeah, idk what else to say other than that I absolutely know this feeling like the back of my hand. this just reminds me of that one time I was up studying for a 9am final and couldn't get to sleep at all and tried all of this stuff and wound up oversleeping and being late to the final.