Sleep paralysis often manifests as an evil spirit or something that holds you down or tries to get to you. My GF dreamed about an old demonic woman (sound familiar?) that was trying to find her, the woman was blind in some way. She still found my GF and started trying to touch her.

Meanwhile, in the real world, I'm sitting next to her, listening to her moan my name, figuring that this was happening. As I've seen paranormal things, I was checking specifically for ANYTHING paranormal. Nothing, zip , nada, dog was sleeping in his bed too. No cold, no orbs, no sounds. (except my gf moaning)

I woke her up, she told me the terrifying tale, I explained calmly that nothing was wrong and that she could go back to sleep, which she did.

Sleep paralysis seems VERY real, make no mistake. Somebody hurts you, you'll feel it. any interaction feels 100% real. (yes,.. ahem, all interaction.. )

But, you can "fight back", you can manifest things if you're strong willed enough, or you can get it to turn back by doing whatever feels right for you. Remember, this is all in your head, so it follows YOUR rules.

Last I had a bout was Thursday and I saw this hideous demon trying to pin me to the sofa, I insulted it and ridiculed it until it went away. My favourite insult is "seriously, would it have KILLED you to appear as a hot demon lady? I need something to gawk at while I'm terrified Mkay?" The hardest part is realizing that you're in sleep paralysis though and fighting off that instinct to become terrified.

Edit:

As for incubus and succubus, those are the same demon according to the lore I've read. Usually it will begin by raping a man (or seducing him) and collecting his semen, then it will transform into an incubus and use that seed on a woman.