Sleep Paralysis

When I go to bed, and I'm dreaming, I noticed it happens when I am having a nightmare, but not all nightmares. I'm basically crying out for help in my dream, but I can't move my mouth, my body is like paralyzed, I can't talk or move my body at all, and it feels like there's something or some kind of pressure on top of me. It's really scary because you try to move your fingers and toes in real life, but you can't because it's as if you're paralyzed. I don't know what cures it, but eventually I just wake up from it. It could be triggered by me having a lot on my mind, I guess. :/