Edited sentence: Although there is no scientific exploration for what causes nightmares, it is commonly believed that anything that gives fear to any person in their lifetime will increase the chances of a nightmare to happen.The actual purpose of nightmares is still very unknown but some people believe there is an actual meaning for what this type of dream means, it is like a hidden message that can not be opened.The causes can be caused by things like bullying, domestic abuse, phobias, anything horror related and even death.The nightmares can be just reminders of things that have happened in the past, other dreams may be fears that need to be conquered and there are those that can never be explained