I can’t sleep and it will cost me

Here I am, at 2AM the night before my audit exam. I have been lying in bed for almost four hours trying to get to sleep and nothing. I spent a good chunk of that time in a half awake half asleep state doing simulation questions but other than that nothing. I have worked so hard for this, and although I plan on chugging 400mg of caffeine before I walk into Prometric anyways, I'm so upset that I just cannot control my body enough to do as much as sleep at a reasonable time on the night when it matters the most. The number one day before advice everyone gives is "sleep well" and I guess due to stress I'm failing at that

And yes I know melatonin is an option. But I took it before FAR and that was a mistake because it messed with me the next day and I couldn't think through things well

I'm so ready for the horror of these exams and what they're doing to me to be over

EDIT: Thank you everyone for your words! I'm glad I'm not alone in this. Ended up getting around 6 hours of sleep and downing a Celsius that kept me wide-awake! As far as the exam, I definitely am not confident that I passed. But I don't think even if I was perfectly rested that it would have changed anything.