One of the things that helped me when I was having similar difficulties with nightmares was to fill my mind just prior to sleep time with relaxing, happy, thoughts or meditative type music, or both. I'd read books with happy messages or funny episodes that were non-violent in nature. Easy listening music that had nothing to do with Cryin', Lovin', or Leavin'!
That's the kind of thing that works for me.
“Life’s journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy ____…! What a ride!’” ~Hunter S. Thompson