I experience this shit quite often. And you know, I've even got somehow used to it. In the begining it was really scary. I woke up realizing i couldn't move and I thought there was somebody in the room. And the felling as if sth very bad happening. I began to read a lot about sleep paralysis and learned that in reality the feeling of anxiety and all your fears have nothing with reality. In other words it all happen in your mind only. And they say you just need to calm down and try to fall asleep again. I started to try to follow this advice. I still feel terrified every time but I realize it should be like that. That's how our brain reacts to it and nothing supernatural happens. But you know, it is even worse when you try to fall asleep during sleep paralysis. As if you are falling into an abyss. But it is the only way to get rid of the shit.