What can be some reasons?

I have been having so many bad dreams and I'm not sure why. They always seem to wake me up but some I remember some i don't. I haven't been watching any scary movies or anything so I don't know why this will be happening. The dreams I remember usually consist of demons, ghost, me dying, someone staring in my window, me getting chased, me drowning just different things almost every day. When I wake up it feels so real. What can be reasons of why this is happening?