I have had a lot of experience with nightmares. If you are suffering from nightmares here are some tips!!
When something happens that worries you and adds a scary image in your mind avoid having nightmares by grabbing a piece of paper and a pencil and writing or drawing your fears. Then rip, crunch, and throw the paper away forever so you will never see it again. Do the same thing in the morning if you had a nightmare.
TIP 2. Before you go to bed put on some relaxing music or hum a happy song. This will be your mind dreamcatcher.
TIP 3. Another way to help is to sing your nightmare out-loud to a classical tune or one of your own tunes.
Bonus Tip. Melatonin is a natural herb you can buy at a store. It helps calm your mind, and really helps me. A store you can buy melatonin at is WHOLE FOODS.