Nightmares are a type of sleep disruption, or parasomnia, characterized by frightening psychological content. Nightmares provoke a feeling of imminent physical danger with a sensation of being trapped or suffocated. These frightening dreams occur during rapid eye movement sleep (REM), or dream-time sleep, and trigger a partial or full awakening. Nightmares are a universal human experience occurring throughout the lifespan. They are especially common in early childhood and involve activation of the limbic brain, particularly the area that mediates negative emotion.
Nightmares are greatly influenced by the particular stressors and anxieties present in the child's waking life. Typical childhood nightmares include dreams of abandonment ; of being lost; of falling; or being chased, bitten, or eaten by a monster or hostile animal. Dream researchers have observed a developmental progression in the content and frequency of children's nightmares. A two-year-old dreamer may recall a fearful dream, but be unable to give form to the source of the threat. By the age of five, the frightened young dreamer may identify the attacker as a monster or wild animal. Older children who have developed more of an understanding of real-life dangers report dreams of pursuit by mean or bad people.
Children gradually develop the ability to understand the difference between dreams and reality. Very young children have great difficulty believing that the dream is not real. By three to four years of age, however, most children can distinguish between the nightmare content and their waking reality.
When a child is awakened by a nightmare she will soon become fully alert and able to remember the scary dream in elaborate detail, expressing emotions appropriate to the dream content. The frightened child will resist returning to bed and often seek the comfort and reassurance of a parent or caretaker. Nightmares are different than the non-dream sleep disturbance known as a night terror, which causes only a partial arousal from deep sleep and occurs during the first period of sleep known as slow-wave sleep (SWS). A child experiencing a night terror will be difficult to awaken or comfort, will not recognize her parent or caretaker, and will usually have no memory of the terrifying emotions that caused the sleep disturbance.
Although infants spend most of their sleep time in the REM stage where dreams are known to occur, there is no reliable way to determine if dreaming actually takes place prior to the development of language and the reflective ability to think in images. Sleep researchers and developmental psychologists generally agree that nightmares first occur in children from 18 months to two years of age. By age three, more than half of all children will report having experienced a nightmare. The incidence of these frightening dreams increases considerably in elementary school children.
In a study of the dreams of four- to 12-year-old children published in the Journal of Clinical Child Psychology in 2000, researchers found that 67.7 percent of four to six year olds, 95.7 percent of seven to nine year olds, and 76.3 percent of ten to 12-year olds reported having had a nightmare experience. Nightmares are common throughout childhood, changing somewhat in content and frequency as children move through different developmental phases and acquire more skills to cope with the changing realities and stresses in their lives.
Causes and symptoms
Childhood nightmares are a normal maintenance function of the developing brain. They are a means of integrating recent and past learning and of establishing psychological equilibrium. Children who have not yet developed sufficient coping mechanisms to deal with many normal childhood fears and problems may feel overwhelmed and insecure. These distressing emotions provide the basis for nightmares. Common stressful events include moving to a different neighborhood or school, encountering a schoolyard bully, watching a horror movie or a violent television or video program, the birth of a sibling, ongoing conflict with siblings, parental marital problems, or any of numerous other stressful situations that may add to a child's sense of vulnerability or powerlessness.
Nightmares may increase and intensify following particularly traumatic events such as the death of a parent, a sibling, or other loved one; parental divorce or separation; an injury, illness, or other medical crises; or witnessing or being subjected to physical or verbal violence or sexual abuse. Children who have been traumatized may suffer ongoing post-traumatic stress and express it through recurring nightmares.
Certain medications used to treat asthma , allergies , and seizures can be a causal factor in the onset of sleep disturbances and nightmares. Abrupt withdrawal from drugs or medications, including barbiturates and benzodiazepines, can also induce these sleep disturbances. Illness with high fever may bring about delirium with frightening episodes of nighttime awakening. The following behaviors are usually present in a normal nightmare episode:
- Child awakens during the last third of her sleep period.
- Child is frightened and becomes fully alert.
- Child can describe the frightening dream in detail.
- Child seeks and responds to comfort and reassurance from a parent or caretaker.
- Child fears a recurrence of the frightful dream and may resist a return to bed.
When to call the doctor
If a child's nightmares increase in frequency and intensity, it is important to consult a physician or pediatrician to determine if the sleep disruption is due to any injury, illness, or infection, or if it might be caused by the use of or change in medications. Disturbed sleeping patterns in children are also present in some cases of juvenile rheumatoid arthritis, autism , and fibromyalgia.
Nightmares usually diminish in frequency and intensity over time. Recurring nightmares may indicate an ongoing problem that the child is having difficulty resolving. A child who is losing sleep and whose fears persist during day-time hours may benefit from the help of a pediatric psychotherapist in developing coping strategies for the stress and anxiety expressed through the dreams.
Parental observation of the child's sleeping patterns and careful record-keeping of symptoms of any sleep disruption through use of a sleep journal will usually reveal any parasomnia patterns that may require professional assessment .
Parents or caretakers should take into account the age and developmental maturity of their child when responding to the fears and anxieties that a nightmare brings to the surface. The child's ability to understand that the nightmare is not real and that it is an event happening only within their own mind increases with age. The nightmare reflects real fears and stressful circumstances present in the child's waking life. A parent's willingness to listen to and sympathize with a child's fears provides a necessary validation of the child's experience and helps to calm the child's anxiety. Very young children who lack the verbal skills to describe the frightening dream may require more reassurances that they are safe and more time in the comforting presence of a parent or caretaker before they are ready to return to bed.
Anne Sayre Wiseman, writing in her book Nightmare Help: A Guide for Parents and Teachers, suggests that parents approach the nightmare as a dream story with a problem to be solved. Parents who act as dream guides can help their children to find their own solution to the dream problem. The parents' goal, Wiseman counsels, is to "encourage autonomy so the child learns to empower themselves at whatever level they can handle."
Alan Siegel and Kelly Bulkeley, writing in their book, Dreamcatching: Every Parent's Guide to Exploring and Understanding Children's Dreams and Nightmares, suggest four beneficial remedies to help a child cope with disturbing nightmares. "The Four R's" of nightmare relief are:
- Reassurance: Provide physical and emotional reassurance and a listening ear so the frightened child will feel safe enough to share the dream images.
- Rescripting: Discuss the dream images with the child and work together with the frightened dreamer to imagine changes in the outcome. Encourage the child to express the images through artwork, fantasy, drama, and writing.
- Rehearsal: Encourage the child to imagine how the various alternative dream endings might change and assist the child in working through the different outcomes to find those that restore a sense of control and safety.
- Resolution: Work with the child to help her discover and acknowledge the life problems and stressful circumstances that may be reflected in the nightmare.
Nightmares are a common childhood parasomnia and medication is rarely indicated. Other parasomnias, such as night terrors and night walking, may call for medication if other interventions and treatments fail to relieve seriously disruptive symptoms.
Teaching the child simple relaxation skills through guided imagery will provide a valuable self-help resource that may minimize bed-time anxiety. Older children can be encouraged to connect with an "inner guide" as a source of strength when they are awakened by frightening dreams. Inner guides may take the form of a loving voice within that the child can listen for during times of fear or a beloved animal that they may call upon as a companionable inner helper when dealing with problems presented in scary dreams.
|Have the child go to bed about the same time every day.|
|Avoid eating or exercising before bed.|
|Avoid scary books or movies before bed.|
|Put the child to sleep with a favorite stuffed toy or special blanket.|
|Keep a nightlight on in the child's room.|
|Keep the door to the child's room open.|
Nightmares are a sleep disturbance that is part of a normal adaptive mechanism of the developing child. They are usually not caused by a child's diet. However fatty foods or spicy meals that may bring about digestive distress at bedtime may trigger sleep disturbances and awaken a child out of an otherwise peaceful slumber.
Childhood nightmares are a normal process of coping with new challenges and integrating new life experiences into the child's understanding of the world. With guidance from a sensitive parent, a child's nightmares can provide an opportunity for parents and children to gain a deeper understanding of, and find solutions to childhood anxieties and insecurities.
Nightmares are part of the normal developmental process that literally provide a "wake-up" call to both parent and child to pay attention to strong feelings and problems that may require some resolution. Nightmares diminish as children feel more confidence and control in their lives. If nightmares persist and intensify they may indicate a situation in the child's life that needs to be changed rather than worked through with dream problem-solving.
Establishing a regular bedtime schedule and routine, including a calming-down period prior to sleep, will help reduce the number of sleep disruptions. Eliminating the stimulation of television or video games at bedtime, particularly violent television shows, movies, and games may reduce the nightmares brought about by these unnecessary and sometimes disturbing stimulations.
Sleep disruptions throughout childhood also cause disruptions for the entire family , particularly parents who must attend to the frightened child and soothe the child back to sleep. Childhood sleep disruptions that persist over time may interfere with the normal sleep-wake cycle of the caregivers. Loss of sleep has a cumulative impact on the well being of both children and adults. Parents may become anxious in sympathy with the child and lie awake in worry long after the frightened dreamer has returned to sleep. There are many good books available to help a parent understand the normal sleep-wake cycles of children and the common parasomnias that all children experience. This knowledge can bring much needed peace of mind and help the parent determine when professional assessment and assistance is appropriate.
Limbic system —A group of structures in the brain that includes the hypothalamus, amygdala, olfactory bulbs, and hippocampus. The limbic system plays an important part in regulation of human moods and emotions. Many psychiatric disorders are related to malfunctioning of the limbic system.
Parasomnia —A type of sleep disorder characterized by abnormal changes in behavior or body functions during sleep, specific stages of sleep, or the transition from sleeping to waking.
Rapid eye movement (REM) sleep —A phase of sleep during which the person's eyes move rapidly beneath the lids. It accounts for 20–25% of sleep time. Dreaming occurs during REM sleep.
Slow-wave sleep (SWS) —Stage of deepest sleep characterized by absence of eye movements, decreased body temperature, and involuntary body movements. Night terrors and sleepwalking occur during this stage of sleep.
Hobson, J. Allan. Dreaming: An Introduction to the Science of Sleep. Oxford: Oxford University Press, 2002.
Moorcroft, William H. Understanding Sleep and Dreaming. New York: Kluwer Academic/Plenum Publishers, 2003.
Schroeder, Carolyn S., and Betty N. Gordon. Assessment and Treatment of Childhood Problems, 2nd ed. New York: Guildford Press, 2002.
Muris, P., et al. "Fears, Worries, and Scary Dreams in 4 to 12 Year Old Children: Their Content, Developmental Pattern, and Origins." Journal of Clinical Child Psychology 29, no. 1 (2000): 43–52. Available online at <www.leaonline.com/doi/abs/10.1207/S15374424jccp2901_5> (accessed August 2, 2004).
National Sleep Foundation. 1522 K Street, NW, Suite 500, Washington, DC 20005. Web site: <www.livingwithillness.com/id174.htm> .
Driver, Helen. "Parasomnias." Canadian Sleep Society. Available online at <www.css.to/sleep/disorders/parasomnia.htm> (accessed October 6, 2004).
Harvie, Jeni. "Disorders: A Wake-up Call for Parents." Sydney Morning Herald, January 29, 2004. Available online at <www.smh.com.au/articles/2004/01/29/10750881124899.html> (accessed October 7, 2004).
National Sleep Foundation. "Sleep Matters." Sleep Problems in Children, Winter 2004. Available online at <www.sleepfoundation.org/features/children_sleep_problems.cfm> (accessed October 6, 2004).
"Nightmares and Night Terrors." Cincinnati Children's Hospital Medical Center. Available online at <www.cincinnatichildrens.org/health/info/growth/diagnose/nightmares.htm> (accessed October 6, 2004).
"Nightmares and Night Terrors in Children." American Academy of Family Physicians. Available online at <www.aafp.org/afp/20000401/2044ph.html> (accessed October 7, 2004).
Siegel, Alan. Nightmare Remedies: Helping Your Child Tame the Demons of the Night. Available online at <www.dreamwisdom.info/library/nightmare_remedies_children_print.htm> (accessed October 6, 2004).
"Sleep Behavior Problems (Parasomnias)." Kids Health for Parents. Available online at <www.kidshealth.org/parent/general/sleep/parasomnia.html> (accessed October 6, 2004).
Hanrahan, Clare. "Nightmares." Gale Encyclopedia of Children's Health: Infancy through Adolescence. 2006. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1G2-3447200403.html
Hanrahan, Clare. "Nightmares." Gale Encyclopedia of Children's Health: Infancy through Adolescence. 2006. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3447200403.html
Possibly deriving from the Old English night and mara, a specter, indicating a terrifying dream. It is said to be caused by a disorder of the digestive functions during sleep, inducing the temporary belief that some animal or demon is sitting on the chest. Among primitive people it was thought that the affliction proceeded from the attentions of an evil spirit.
Johann Georg Keysler, in his work Antiquitates selectae Septentrionales et Celticae (1720), collected interesting particulars concerning the nightmare. Nactmar, he stated, is from Mair, an old woman, because the specter which appears to press upon the breast and impede the action of the lungs is generally in that form. The English and Dutch words coincide with the German. The French cochemar is Mulier incumbens or incubus. The Swedes use Mara alone, according to the Historia de omnibus Gothorum Sueonumque Regibus of J. Magnus (1554), where he stated that Valender, the son of Suercher, succeeded to the throne of his father, who was suffocated by a demon in his sleep, of that kind which by the scribes is called Mara.
Others "we suppose Germans," continued Keysler, "call it Hanon Tramp. " The French peasantry called it Dianus which is a corruption either of Diana or of Daezmonium Meridianum for it seems there is a belief which Keysler thought might not improbably be derived from a false interpretation of an expression in the 91st Psalm ("the destruction that wasteth at noonday") that persons are most exposed to such attacks at that time and therefore women in childbed are then never left alone.
But though the Daezmonium Meridianum is often used for the Ephialtes, nevertheless it is more correctly any sudden and violent attack which is deprives the patient of his senses.
In some parts of Germany, the name given to this disorder is das Alpdructen, either from the "mass" which appears to press on the sufferer or from Alp or Alf (elf). In Franconia it is die Drud or das Druddructern, from the Druid or Weird Women, and there is a belief that it may not only be chased away, but be made to appear on the morrow in a human shape, and lend something required of it by the following charm: "Druid tomorrow / So will I borrow."
These Druids, it seems were not only in the habit of riding men, but also horses, and in order to keep them out of the stables, the salutary pentalpha (which bears the name of Drudenfuss (Druids foot) should be written on the stable doors, in consecrated chalk on the night of St. Walburgh. It should also be mentioned that the English familiar appellation "Trot" as traced to "Druid," "a decrepit old woman such as the Sagas might be," and the same might perhaps be said of a Scottish Saint, Triduana or Tredwin.
In the Glossarium Suiogothicum of Johann Ihre (1769), a somewhat different account of the Mara is given. Here again, we find the "witch-riding" of horses, against which a stone amulet was suggested by the antiquarian John Aubrey, similar to one described below.
Among the incantations by which the nightmare may be chased away, Reginald Scot recorded the following in his Discovery of Witchcraft (1584):
St. George, St. George, or lady's knight, He walked by day so did he by night: Until such times as he her found, He her beat and he her bound, Until her troth to him plight, He would not come to her that night.
"Item," continued this author, "hand a stone over the afflicted person's bed, which stone hath naturally such a hole in it, as wherein a string may be put through it, and so be hanged over the diseased or bewitched party, be it man, woman, or horse."
Readers of these lines may be reminded of the similar charm which Shakespeare put into the mouth of Edgar as Mad Tom in King Lear:
Saint Withold footed thrice the wold: He met the night-mare and her ninefold Bid her alight, And her troth plight And aroint thee, witch, aroint thee.
Another charm of earlier date occurs in Chaucer's Miller's Tale. When the simple Carpenter discovers the crafty Nicholas in his feigned abstraction, he thinks he may perhaps be hagridden, and address him thus:
I crouch from the Elves and fro wikid wightes And there with the night-spell he seide arightes, On four halvis of the house about, And on the dreshfold of the dore without, 'Jesus Christ, and seint Benedight, Blesse this house from evrey wikid wight, Fro the night's mare, the wite paternoster, Where wennist thou Seint Peter's sister.
A later author has pointed to some other formularies, and has noticed the Asmodeus was the fiend of most evil repute on these occasions. In the Otia Imperiala of Gervase of Tilbury, some other protecting charms are said to exist.
To turn the medical history of the incubus, Pliny recommended two remedies for this complaint, one of which was the herbal remedy wild peony seed. Another, which it would not be easy to discover in any modern pharmacopoeia, was a decoction in wine and oil of the tongue, eyes, liver, and bowels of a dragon, wherewith, after it has been left to cool all night in the open air, the patient should be anointed every morning and evening.
Dr. Bond, a physician, who stated that he himself was much afflicted with the nightmare, published an Essay on the Incubus in 1753. At the time at which he wrote, medical attention appears to have been very little called to the disease, and some of the opinions hazarded were sufficiently wild and inconclusive. Thus, a certain Dr. Willis said it was owing to some incongruous matter which is mixed with the nervous fluid in the cerebellum (de Anima Brutorum ), while Bellini thought it imaginary and to be attributed to the idea of some demon which existed in the mind the day before.
Both of these writers might have known better if they would have turned to Fuchsius (with whom Dr. Bond appeared to be equally acquainted), who in his work de Curandi Ratione, published as early as 1548, had an excellent chapter (I, 31) on the causes, symptoms, and cure of nightmare, in which he attributed it to repletion and indigestion, and recommends the customary discipline.
Much of Gothic literature has been ascribed to dreams and nightmares. Horace Walpole's famous story The Castle of Otranto (1764) derived from a dream in which Walpole saw upon the uppermost banister of a great staircase a vision of a gigantic hand in armor.
In 1816, Mary Shelley had a gruesome and vivid nightmare which was the basis for her story Frankenstein.
Nearly seventy years later, novelist Robert Louis Stevenson had a nightmare that inspired his famous story The Strange Case of Dr. Jekyll and Mr. Hyde, which he completed in only three days.
Bram Stoker's immortal creation of Dracula (1897) was claimed to be the result of a nightmare after a supper of dressed crab, although clearly many of the elements in the story had been germinating in the author's mind much earlier. Many horror stories have also been inspired nightmares.
(See also fiction ; Succubus )
"Nightmare." Encyclopedia of Occultism and Parapsychology. 2001. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1G2-3403803300.html
"Nightmare." Encyclopedia of Occultism and Parapsychology. 2001. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3403803300.html
Nightmares are dreams whose contents are unpleasant or anxiety provoking and which, depending on their intensity, can awaken the sleeper. Also known as anxiety dreams, nightmares attracted the interest of Sigmund Freud, who refers to them for the first time in The Interpretation of Dreams. There, he shows how nightmares are not an exception to dream theory and, more specifically, that they are consistent with the theory that dreams are the fulfillment of a wish. The anxiety experienced during the nightmare can only be apparently explained by its content. Although intrinsically linked to its accompanying representations, the anxiety arises from a different source. In this sense the anxiety of the dream is identical to the anxiety experienced during neurosis.
Based on this analogy, Freud claims that nightmares are dreams with a sexual content whose libido is transformed into anxiety. The content is generally exempt from any form of distortion and represents the unveiled realization of a repressed desire that has shown itself to be stronger than censorship. The anxiety that accompanies the dream then takes the place of the censorship.
Nightmares can awaken the dreamer, and sleep can be interrupted before the dream's repressed desire has, faced with the censorship, reached its complete realization. In this case there is a failure to form the compromise that constitutes the dream, which then fails to fulfill its function as the guardian of sleep.
Although Freud did not change his dream theory, he updated it in Beyond the Pleasure Principle (1920). The repetitive anxiety dreams observed in people suffering from traumatic neuroses cannot be explained by the fulfillment of a repressed desire. In these nightmares a profoundly unpleasant and anxiety provoking event is repeated. To explain this, Freud introduces the hypothesis that the dream serves to bind the instinctual excitation to avoid overwhelming the psychic apparatus with traumatic material. In traumatic neurosis this binding function is disturbed.
Ernest Jones, in his book On the Nightmare, interpreted anxiety dreams as the fulfillment of a repressed wish associated with infantile sexuality. More recently, French authors, relying on experimental findings that reveal that through the different paradoxical sleep cycles the same dream matter becomes increasingly less comfortable as dreaming progresses, have hypothesized that this phenomenon may be the reflection of the dream's work of organization, integration, or binding. This would result in the gradual development of the most archaic signifiers, increasing their complexity, combining them, and dramatizing them in primary fantasies that have been relegated to secondary importance. According to this assumption, nightmares are the reflection of the failure of these binding processes, whereby anxiety occurs through the inability to repress archaic signifiers.
See also: Annihilation anxiety; Anxiety dream; Cinema and psychoanalysis; "From the History of an Infantile Neurosis" (Wolf Man); Garma, Angel; Pasche, Francis Léopold Philippe; Phobias in children; Secrets of a Soul ; Traumatic neurosis; War neurosis.
Freud, Sigmund (1900a). The interpretation of dreams. SE, 4-5.
——. (1920g). Beyond the pleasure principle. SE, 15: 273-338.
Golse, Bernard. (1992). Cauchemars, rêves et processus de pensée. Psychiatrie de l'Enfant, 37, 2, 395-413.
Houzel, Didier. (1980). Rêve et psychopathologie de l'enfant. Neuropsychiatrie de l'Enfance et de l'Adolescence, 28, 155-164.
Jones, Ernest. (1949). On the nightmare. London: Hogarth Press and the Institute of Psycho-Analysis.
Metello, Philippe. "Nightmare." International Dictionary of Psychoanalysis. 2005. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1G2-3435300984.html
Metello, Philippe. "Nightmare." International Dictionary of Psychoanalysis. 2005. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3435300984.html
A frightening dream that occurs during REM (rapid eye movement) sleep.
Nightmares—frightening dreams—are experienced by most everyone at one time or another. Nightmares are thought to be caused by a central nervous system response, and are related to other parasomnias such as sleepwalking.
In children, nightmares begin between the ages of 18 months and three years and increase in frequency and intensity around the ages of four and five years. Children this age have an exceptionally vivid fantasy life that carries over into their sleep . Their nightmares are typically characterized by feelings of danger and helplessness and often involve fleeing from monsters or wild animals. It is not unusual for a normal child this age to have nightmares as often as once or twice a week. The increase in nightmares among preschoolers reflects not only their capacity for vivid fantasy but also the fact that as they become increasingly active, their daily lives hold more opportunities for frightening experiences, and growing interaction with peers and siblings produces added potential for conflict and tension. Separation anxiety and exposure to frightening programs on television are additional sources of emotional turbulence.
The American Psychiatric Association's Diagnostic and Statistical Manual (DSM-IV) recognizes an anxiety disorder characterized by persistent, severe nightmares (nightmare disorder, formerly dream anxiety disorder). Generally, nightmare disorder is found only in children who have experienced severe psychological stress .
Adults also occasionally experience nightmares. The average college student has between four and eight nightmares per year, and this figure generally drops to one or two in adults. Adults who experience excessive nightmares may be dealing with other issues, and may benefit from professional counseling.
"Nightmares." Gale Encyclopedia of Psychology. 2001. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1G2-3406000459.html
"Nightmares." Gale Encyclopedia of Psychology. 2001. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3406000459.html
night·mare / ˈnītˌme(ə)r/ • n. a frightening or unpleasant dream: I had nightmares after watching the horror movie. ∎ a terrifying or very unpleasant experience or prospect: the nightmare of racial hatred | an astronaut's worst nightmare is getting detached during an extravehicle activity. ∎ a person, thing, or situation that is very difficult to deal with: buying wine can be a nightmare if you don't know enough about it. DERIVATIVES: night·mar·ish adj. night·mar·ish·ly adv.
"nightmare." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1O999-nightmare.html
"nightmare." The Oxford Pocket Dictionary of Current English. 2009. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-nightmare.html
T. F. HOAD. "nightmare." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1O27-nightmare.html
T. F. HOAD. "nightmare." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-nightmare.html
ELIZABETH KNOWLES. "nightmare." The Oxford Dictionary of Phrase and Fable. 2006. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1O214-nightmare.html
ELIZABETH KNOWLES. "nightmare." The Oxford Dictionary of Phrase and Fable. 2006. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O214-nightmare.html
"nightmare." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (June 30, 2016). http://www.encyclopedia.com/doc/1O233-nightmare.html
"nightmare." Oxford Dictionary of Rhymes. 2007. Retrieved June 30, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-nightmare.html