3am thoughts are undefeated. how do you actually sleep before exams

mid sems in 2 weeks. every night i lie down at 12, brain goes "hey remember that thing you said in 9th std" and then it's 3am and i'm googling whether 4 hours of sleep is enough to pass thermodynamics. tried the meditation app, fell asleep once in 20 tries. tried no phone in bed, just stared at the ceiling instead. one guy on my floor takes his mom's sleeping tablets and i am not doing that. is this just exam stress or is this the anxiety thing. how do you guys turn your brain off. real answers pls not "just relax bro".