Studied all semester but blanking on past papers 3 days before exam — sleep deprived and burnt out. Any tips?

I have a statistics psychology exam on June 17th and I’m starting to panic a little.
For context, I’ve been really on top of this subject all semester — studying the weekly content consistently, doing lots of practice test questions (both theory and calculations), and meeting with a tutor weekly. I genuinely feel like I understand the material when I’m going through notes or studying normally.

But these past few days when I’ve been doing past papers, my brain just… doesn’t work. I can’t properly apply what I know. I’ll read a question and just blank, or second-guess myself on things I was confident about before.
The complicating factor: I’ve been sleeping less than 8 hours a night for the past 5 days because I had other exams back to back. My body is exhausted but weirdly wired at the same time — like I can’t properly rest even when I try.
I know the content. I’ve put in the work.

But right now I feel like none of it is accessible when it counts.
Has anyone been in this situation before? Any tips on how to:
• Actually get proper sleep when you’re in that overtired-but-wired state?
• Recover your ability to apply knowledge in exam conditions when you’re burnt out?
• Make the best use of the last 3 days before the exam?

I really need help. Any advice appreciated 🙏