Re: Sleep paralysis
from what ive read, its a throwback to when we were more primitive. y'know..sleepin in trees and stuff to avoid predators. when we sleep, our minds are active and our bodies would be too. kinda like how a dog barks and fake runs while theyre sleepin. so, the paralysis thing was meant to keep us from thrashin about and fallin out of the trees. so, the involuntary paralysis, plus the semi awake mind, winds up creating a very stressful situation. you cant move, and you're awake realizing that you cant move.
then, there are some people who believe that they have been abducted by aliens or something and the paralysis is how they keep ya from moving, or even keep you from noticing that you have been taken and brought back. that would explain the feeling of a presence.... all pure speculation.
i vote for the biological paralysis with the conscious awareness idea.