In poetic myth, the Nightmare is actually a “small nettlesome mare, not more than thirteen hands high, of the breed familiar with the Elgin marbles: cream-colored, clean-limbed, with a long head, bluish eye, flowing mane and tail.” Her nests, called mares’ nests, “when one comes across them in dreams, lodged in rock-clefs or the branches of enormous hollow yews, are built of carefully chosen twigs lined with white horse-hair and the plumage of prophetic birds and littered with the jaw-bones and entrails of poets.”

Thus, in a pagan world of myth and blood sacrifice, the Nightmare was a cruel, fearful creature. Our modern word nightmare derives from the Middle English nihtmare (from niht, night, and mare, demon), an evil spirit believed to haunt and suffocate sleeping people. And so, in today’s world, when we speak of a nightmare we mean a frightening dream accompanied by a sensation of oppression and helplessness.

The blood-thirsty aspect of the mythic Nightmare, however, can give a good clue about nightmares in general, for in psychodynamic terms nightmares are graphic depictions of raw, primitive emotions such as aggression and rage that have not been incorporated into the conscious psyche. Thus we tend to encounter these “ugly” aspects of our unconscious lives as terrifying dream images in whose presence we feel completely helpless.

Nightmares are quite common in childhood because this is a time of our emotional development when we all have to come to terms with, well, raw, primitive emotions such as aggression and rage.

Traumatic nightmares can also occur as one of the many symptoms of posttraumatic stress disorder (PTSD). Repetitive, intrusive nightmares following a trauma often contain symbolic themes that mirror the original trauma and relate to threat to life, threat of abandonment or death, or loss of identity.

Therefore, traumatic nightmares need to be treated differently than other dreams. It’s not enough just to “know” intellectually the psychological reasons why you have these nightmares. An event is traumatic because it disrupts your previously secure—and illusory—sense of “self.” And so, to heal from a trauma, you must take the initiative to make conscious changes in your life to accommodate the traumatic shattering of your illusions about life and identity.

Some believe that nightmares have a physiological nature as well. Edgar Cayce believed that Nightmares, which bring with them an inability to move or cry out, usually indicate the wrong diet. To end the nightmarish dreams change your diet.

We found a technique online that can help people who suffer from recurrent nightmares. It is not meant to be a cure-all. It is just a suggested treatment to deal with frightening nightmares. The idea is to use this therapy every night until the nightmare has been resolved. It is called Imagery Rehearsal Therapy.

Here are the steps of Imagery Rehearsal Therapy:

Write out the text of the nightmare. Tell the story, no matter how frightening, in as much detail as you can remember.
Create a new ending for the nightmare story and write it out. Be careful, however, to make the new ending peaceful. Remember that the nightmare is grounded in emotions such as raw anger that have been provoked by a trauma. The point of a new ending is to “tame” the emotions, not merely vent them in violence and revenge.
Rehearse the new version of the story in your imagination each night just before going to sleep. Do this as close as possible to your falling asleep without any other activity between the rehearsal and sleep.
Perform a relaxation exercise. Do this immediately after the rehearsal, as a way to fall asleep peacefully. You may use any technique with which you are familiar. This could be meditation, yoga, or breathing exercises.

The “cousin” of nightmares is disturbing dreams with unpleasant images.