How can I stop this and get over it?

I watched a bunch of scary movies.... Anyways, whenever I'm in my room at night ALONE, in the dark, I get scared and think of all the scary images from the movies, I'm 14, barley. And ya, when I'm sleeping by my lil bro I'm fine in the dark and stuff, but when I'm alone I flip. Rit now I'm alone...in my room with the lights on. I normally could sleep on my own, now I'm just freaked out...