I've had a wide variety of sleep disorders since I was a kid, including sleep paralysis. It has occurred more since being an adult, but it's been a year or two since the last time I experienced it though.
I believe I originally developed sleeping disorders because my parents would often argue in the middle of the night. This led to frequent disturbance of my natural sleeping patterns and anxiety about sleep. This then led to insomnia, lucid dreaming, blurring between sleeping/wakefullness, and sleep paralysis, among others.
I had an early, intrinsic understanding that these various states were caused by these stresses and never had the inclination to attribute any 'supernatural' significance to them.
Sleep paralysis itself is one of the worst sleep disorder manifestations because, no matter how much you intellectually understand what's happening, it is almost always scary and disturbing. I know there is nobody/nothing in the room with me, but you still feel as though there is - and the more you try to fight being paralyzed, the harder it is to break out of it.
I've read a lot about these types of things over the years, and it is interesting how various people interpret these experiences - from alien abductions to seeing demons and ghosts. Having personally had sleep paralysis, I can understand how different people would interpret the experience based on their beliefs/personality, but it also has given me insight to how susceptible people are to irrationality.
Ironically, experiencing sleep paralysis is one of the primary experiences which has given me more confidence in my rational/skeptic view of the world, as it has allowed me to view things from both sides.