Take whatever I say with a grain of salt, but I feel intentions(not to be confused with intentionality) help a lot here. They play a distinctive role in the etiology of attention(and the subsequent process of resilience building), one of the fundamental aspect of dealing with psychological issues. For eg, Whenever you become aware of these nightmares, try to observe the casual chain, eventually your mind will be inured to these episodes and will become much better at threat detection. Something like a mindfulness(Vipassana) retreat can help with this a lot.

My experience has been that most of the psychological issues can be resolved to a great extent by employing the "redundancy of potential command a.k.a Self-Organization"(See McCulloch). Meditation does this by asking you to bring back the wandering mind again and again. But you can also do this voluntarily by repeatedly observing the stress inducing conditions such as nightmare(in your case), which can help your brain better adjust and detect patterns.