depends on what type of nightmare. If it is just a normal run of the mill type nightmare. I do nothing because it most likely won't happen with the same exact nightmare content and so on. But if it is what I call a feel true come true type nightmare and I have it more than once I know that the nightmare is part of my "memory cycle" (new memorys coming into my conscious awareness level). for those type of nightmares I know what whatever the nightmare is, is something that I actually experienced. Each of them what I do for them varies. and basically what I do is journalling, art work and crafts and so on to trigger more memories about it.Most times they start out with my not knowing anything but when I wake up in panic I grab my journal and write what is going on, my feelings and so on. Once I have something to go on I use what ever triggers that I know that will match it to push it into moving forwards. then I journal, make shoe box versions of it (diaramas) and so on until I remember the whole thing. when I can remember the whole nightmare and the situation it is about the nightmare goes away.