system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly causes hallucinations during sleep paralysis and why are they always scary?
gpt
I occasionally have sleep paralysis and from what I've read sleep paralysis is when you have a disturbance in your REM sleeping cycle. You're mind is active but your nodu is still asleep.

The hallucinations come from the fact that your mind is aware that your body is in a state of paralysis, which leaves us in a very vulnerable state. When we feel vulnerable our amygdala perceives threats that aren't there(hallucinations). When we perceive these threats our body goes into flight -or- fight mode and with our bodies being paralyzed it creates severe panic and fear and the hallucinations get worse. 

TL:DR The state of being awake when your body is asleep makes your brain think your in danger and manifest dangers that aren't actually there.