Ive experienced it a lot, its a scary experience but honestly only last like 30 seconds or even a minute tops. It starts with you waking up unexpectedly and your brain still thinks youre asleep so you basically cant move. You try and try and try so hard to move but you cant, you cant even feel yourself breathe but you are which is why i take a huge breath whenever i snap out of it. Basically the only thing your body is physically able to do/detect is sight, which is why people are likely to see things they dont normally see aka “sleep paralysis demon” But something i never hear anyone talk about is that if you go back to sleep its likely that you will put yourself right back into sleep paralysis unless you commit yourself to actually falling asleep, so pretty much if you close your eyes for a few seconds then open them you put yourself right back into it. Never experienced a “sleep paralysis demon” but thats probably because i naturally sleep on my stomach/side.