Imagery rehearsal therapy is an evidence-based brief intervention shown in research to be highly effective in eliminating nightmares. It’s frequently used in treatment of PTSD, in conjunction with other approaches that focus more generally on reduction of posttraumatic symptoms.1

It involves written recollection of a targeted nightmare, followed by guided methods for cognitive rescripting that results in nightmare resolution.

1. https://www.behavioralsleep.org/index.php/sbsm/about-adult-sleep-disorders/nightmares