Can anyone help me with this crazy dream?

A few nights ago I had a REALLY crazy dream. So in my dream, I looked out of my room and into the hallway and saw a woman walk into my room very slowly. As she got halfway into my room, she stopped and looked at me and then her eyes and mouth turned pitch black and she started screaming, like she was possessed, at me. I couldn't move or scream or do anything. But the weird part about the dream was I thought that I was awake and actually saw it. I read somewhere that I actually was awake and hallucinated the woman coming into my room, but I kind of don't believe it. Can anyone tell me if this is true or not? Thank you :)