Could have been demons not aliens. I've heard about this happening to at least three people in my life. One a child the other two adults. Same situation, they couldn't move or speak and where terrified to death. They all saw or felt some sort of presence. All of them told about how they couldn't move and felt like "something" was holding them down. You should start to pray before you go to sleep. Even if it's just the Lord's prayer. I don't know what these types of things that happen means, but I would pray over the place where I sleep and start to develop a stronger relationship with God. He's always listening and patiently waiting to hear from us. Pray honey and I will pray for you as well. Blessings.