Repetitive Nightmare Solutions
I am of the opinion that nightmares are the brain's way of waking a person up if they are dangerously hot or cold, so that something can be done about it. Nightmares are often repetitive, you get the same one over and over. To prevent a nightmare repeating itself, all you have to do is go through in your mind the whole nightmare as vividly as possible and then give the nightmare a happy ending. Next time you repeat the nightmare you will dream the happy ending you have created and not wake up. So, for example, if you are being chased through a forest by a monster, you visualize turning round, getting an axe out of your belt and using it on the monster. And the nightmare is vanquished too.
In order to prevent getting too hot or cold in the first place a few adjustments of the bedroom will be needed in order to make a more comfortable temperature for sleep, so that your brain does not need to wake you up.