Scary sleep paralysis is based purely on expectation. I have it regularly, sometimes 6+ times I'll wake up with it in a night. It's only as scary as you think it'll be. Think about it, it happens because you're partially awake but your brain isn't entirely aware of it, like
>>2540757 said, so it keeps you still like usual, to keep you from acting out your dreams. So, you're half awake, half dreaming. So, if you panic, you're gonna have a nightmarish experience. If you relax, then it can be very relaxing and pleasant, and is a good way to start lucid dreaming, like
>>2544328 said. Some people intentionally induce sleep paralysis, for this reason.
>>2541444 (checked)Sounds like Exploding Head Syndrome. Don't know who named that shit, it's not that crazy. I get it sometimes, usually when I'm really really tired, not as bad as you though. Just try to relax. The half asleep brain is very susceptible to suggestion. It will follow your conscious mind. Panic and it'll give you a reason. Relax and you'll be fine.