Why do I keep having this recurring nightmare?

Ok i've been having this dream since I was 6-8 then i thought it was over but now all these years later its come back just last night. The dream is me in my house with no lights on and all of a sudden all of these formless spirits knock on my windows and scream and yell to be let in. And each time i have it this one window in the house starts to crack even more. I don't ociate myself with witch craft or anything. But if this helps when i was little i played with pokemon cards during the time the dream would appear. And i just started to look at them again and the dream reappeared...Help! Thanks