Is it hallucinations? How can I prevent it from happening?

It could be possible that you were actually sleepwalking believe it or not! When you sleepwalk you are having a dream so intense that you're body moves accordingly. The reason why you were crying and screaming was that you woke up in the hallway and thought it was real. I can relate to this because something like this happened to me once. I once woke up one night and went to the living room. Then I saw my dads spirit come out of his . (yes his ) then i chased the spirit around and pushed it back into him with a pillow. Then I woke up but I actually thought it was real. I told my mom, who in the dream actually saw me do it, but she told me that I was just DREAMING (My mom found me wandering around so she took me back to bed [ I was like 5 or six back then]) I still remember that experience suprisingly. lol