I used to get nightmares every night. I could limit them a bit by what I exposed myself to in the media. Other than that the only thing that has worked has been working on the trauma itself. The nightmares are purely a way of your mind telling you its still wounded.

I know this isn't much comfort and I know what nightmares and the horrible feeling all day the day after is like. The only thing to relieve it at the time was my therapist suggested I buy a cuddly toy. It worked and I still sleep with it. It give comfort after but does nothing to stop them.