How do you get over a bad dream?

My dreams have taken a turn for the worse lately [possibly because of stress from school], and the really bad ones haunt me for days on end. Since school stress isn’t going to go away any time soon, I’m hoping to at least cope better with my strange nightmares [the latest one was a secret society + cannibalism + plagiarism + timed exams. Bizarre!]

So what do you guys do when you need to forget a bad dream…?