I found this fascinating article about using artificial dreams to deal with PTSD nightmares. I know that I've got some readers with PTSD so I figured that sharing this might be helpful. The basic concept involves 3D images of family members being supportive. Looking at the technique, I suspect one could try a kitchen-sink version at home by creating a plain 2D video of whatever one finds comforting and cheering, to watch as needed. When I was little, I dealt with nightmares by getting out of bed and reading a favorite book, deliberately shifting my thoughts in a calmer direction; that kind of redirection works tolerably well. PTSD is basically a pattern-burn problem, so catching it when it triggers and rerouting the mind toward something more positive should help at least somewhat.