You have to know who you are, if you don't you have nightmares.
Some nightmares are fairly normal for young children and often originate from fears, anxiety, and misunderstanding. Usually these are fairly typical and are sometimes caused by immature and inadequate processing and understanding of what is and has gone on in the child’s life. Sometimes nightmares arise from trauma or more significant anxiety or stressors. In these cases, responsible adults need to do what they can to reduce the turmoil causing this, and likely other problems for the child. Sometimes the nightmares arise from the viewing of inappropriate entertainment. This viewing, even on an occasional basis can cause behavioral and psychological problems beyond the nightmare or even night terror. Terminate the viewing or even hearing of these types of entertainment completely. That usually means that when the child is in the house, you don’t watch it either because you don’t know what the child may hear or if the child may get up for some reason and you certainly don’t want to be punitive of your child for getting up in the night on an irregular basis for brief periods of time because they feel they need you.
When there is trauma in the life of the child, even if only witnessed, eliminating the trauma and processing through play therapy can be very beneficial.
For simple, common nightmares, helping your child to reframe the nightmare into an empowering process through lucid dreaming can be very helpful.
As soon as the child has the nightmare, have them tell you about it and then ask them if they could change something about the dream to make it more pleasant, such as imagining the scary wolf to be a small friendly puppy. When my oldest was about five, she was having bad dreams about dark shadowy ghosts. We talked about it and since she had seen cartoons of Casper the Friendly Ghost, I asked if she could imagine the ghosts in her dream looked like Casper. She matter of factly responded and said “no” they are pink. That was the end of the problem.
Nightmares and Night Terrors in Children
Nightmares: Children’s WebMD
How to stop nightmares in children
Nightmare Remedies: Helping Your Child Tame the Demons of the Night
Stress HELPING YOUR CHILDREN (and you) THROUGH TIMES OF STRESS
Autism, Anxiety and Nightmares
LDS Parent: Taming Nightmares