Sleep paralysis has a well documented correlation with anxiety and stressful life situations. I get sleep paralysis pretty often, I usually have hallucinations and a feeling that someone else is in my room. Fortunately I don't experience any feeling of suffocation that often goes hand in hand with it.
The most intense episode was when I was lying on my side as I woke up into sleep paralysis, then the hallucinations started. I have a poster of a pin-up model that in my room that I was facing, and her tongue was sticking out and making all sorts of horrific facial expressions, first pain, then anger and hate. Then I notice that the pile of clothes underneath the poster looked like a pile of dead bodies, thats when I could have sworn someone opened the door and was speaking to me, but then I woke up and felt completely normal. I don't think I've ever hallucinated like that in my life, and I am no stranger to psilocybin or LSD.
Definitely not pleasant by any means, but it was an interesting experience looking back on it. I use opiates rather frequently and they are known to cause intense dreams, that might explain why the hallucinations I get when I'm sleep paralyzed are so intense.