A nightmare is frequently defined as a long, frightening dream that awakens the sleeper. The assumption underlying the use of the waking criterion in defining nightmares is that sleepers awaken from a nightmare because of the extreme intensity of the emotions experienced within it. If the magnitude of negative emotions in a dream is not great enough to awaken the sleeper, then the dream is not sufficiently disturbing to be classified as a nightmare. Although a causal link between emotional intensity and awakening from a dream is a plausible hypothesis, there is no empirical evidence to support this view. On the contrary, evidence exists to support the idea that even the most unpleasant of dreams do not necessarily awaken the sleeper. Based on data from more recent studies, some researchers have suggested that disturbing dreams which awaken the sleeper should be called “nightmares” whereas disturbing dreams which do not awaken the sleeper should be called “bad dreams.”

Several reports have also shown that although fear is the most common emotion in disturbing dreams, these dreams can also contain a variety of other unpleasant emotions such as anger, sadness, and frustration. A nightmare is thus defined as a disturbing dream in which the unpleasant visual imagery and/or emotions awaken the sleeper. A bad dream is a disturbing dream which, though being unpleasant, does not cause the dreamer to wake up.

Nightmares Versus Sleep Terrors

Traditionally, the term “nightmare” has been used to refer to two distinct types of sleep phenomena, actual nightmares and what are known as sleep terrors. However, nightmares and night terrors can be differentiated both biologically and psychologically. For example, nightmares are characterized by the presence of vivid visual imagery (frequently situations in which the dreamer is in danger) and strong negative affect (e.g., intense fear, anxiety, or guilt). These dreams are usually remembered in detail, typically end with the subject’s waking up (in a non-confused state), and occur largely in REM sleep during the second half of the night. By contrast, sleep terrors (sometimes called pavor nucturnus in children and incubus attack in adults) are marked by a sense of confusion upon awakening, the usual absence of recall of elaborate dream imagery, and the presence of intense autonomic activation. They typically occur in slow-wave sleep (stage 3-4 sleep) during the first hours of sleep, and amnesia for the entire episode is typical upon awakening in the morning.

Prevalence of Nightmares

Approximately 5% to 7% of adults report a current problem with nightmares. Two surveys have assessed the incidence of complaints of nightmares, rather than the general rate of nightmare occurrence, in the general public. Together, these two surveys indicate that 5% to 8% of the general population report a current problem with nightmares, with about 6% reporting a previous complaint. In a national survey of over 4000 physicians, 4% of patients reported nightmares as one of their complaints in the course of the interviews. More recent studies indicate that the prevalence of nightmares may be considerably higher. Among clinical populations, approximately 24% of non-psychotic patients seen in psychiatric emergency services report nightmares. Similarly, approximately 25% of both chronic male alcoholics and female alcohol and drug users report having nightmares every few nights. Although nightmares can occur in “normal” individuals, they have been documented to occur as a concomitant of numerous traumatic experiences. For example, the occurrence of nightmares has been reported in subjects with post-traumatic stress disorder; combat veterans; survivors of the Holocaust ; Latin American survivors of torture; prisoners of war; survivors of natural disasters; young victims of kidnapping; the sexually abused; refugees.

Nightmares and Psychopathology

Much of the previous nightmare research had been dedicated to investigating the possible association between nightmare frequency and psychopathology. Though most studies have found a relationship, others have not. Taken together, these studies indicate that in at least some people who report nightmares there exists a relationship between nightmare frequency and psychopathology. The nature of this relationship, however, remains unclear. Moreover, no single measure or pattern of psychopathology has been exclusively or consistently associated with nightmare frequency.

Theories of Nightmares

– Early Views

Early views on nightmares centered around the idea that nightmares involved the visitations of monsters, demons, ghosts, or other evil spirits. In his work On the Nightmare, Ernest Jones (1931) examined the extent to which dreams influenced the development of various beliefs about the soul. He argued that nightmares contributed to the rise of superstitious beliefs in incubi, vampires, werewolves, devils and witchcraft. Jones also cites mythologists who suggested that the belief in all kinds of spirits could be traced to the experiences of the nightmare. For instance, he quotes from Golther (1895) who writes that “The belief in the soul rests in great part on the conception of torturing and oppressing spirits. Only as a gradual extension of this did the belief arise in spirits that displayed other activities than torturing and oppressing. In the first place, however, the belief in spirits took its origin in the Nightmare”.

– Freud
Though Freud was a certainly a prolific writer (his collected publications amount to twenty-four volumes and he wrote extensively about dreams in twenty-six different articles or books) he had surprisingly little to say about nightmares. Nightmares, which awaken the dreamer, are counterexamples to Freud’s theory which emphasizes that dreams are ‘the guardians of sleep.’ Freud (1920) included nightmares in his wish-fulfillment theory of dreams by suggesting that nightmares represented wishes for punishment emanating from the superego. By 1925, Freud had included aggression as a primary drive in his drive theory, and posited that nightmares were “an expression of immoral, incestuous and perverse impulses or of murderous and sadistic lusts”. Freud apparently became dissatisfied with this initial explanation of nightmares and recognized that his theory did not adequately explain recurrent (traumatic) nightmares. He later tried to account for recurrent nightmares by suggesting that they represented a “repetition compulsion” ó a primitive and regressive tendency to recreate unpleasant experiences (Freud, 1955). However, several psychoanalysts have continued to argue that recurrent nightmares, no matter how disturbing the dream content, represent the fulfillment of disguised unconscious wishes.

– Jung
Jung believed that nightmares, like most other types of dreams, serve a compensatory function. If people became too flippant or perfunctory in their conscious attitude, then a dream could enhance the situation and compensate for that waking state in a way that produced a nightmare. Similarly, nightmares could “shock” a dreamer in order to impart messages difficult for that person to accept. Traumatic nightmares, however, are not viewed in Jungian dream theory as being compensatory because they are largely unrelated to the dreamer’s conscious attitude and “conscious assimilation of the fragment [of the psyche] reproduced by the dream does not . . . put an end to the disturbance which determined the dreams”.