Nightmares

Nightmares have been reported to occur in a large percentage of the population following an intensely frightening or highly emotional experience (Hefez et al., 1987; Ross et al., 1989).

They may also exist as recurrent episodes, and certain subgroups have been investigated thoroughly (concentration camp survivors, Viet Nam war veterans, bus or airplane hijack victims, etc.) (Grinker et al., 1945; Ross et al., 1989).

Studies have suggested that, depending on their frequency and on the psychological profile of the subject, nightmares may have a negative disturbing impact on the subject's daytime behavior and on his/her relations with the surrounding environment, and could be the basis of a neuropsychiatric syndrome (Levin et al., 1991; Hudson et al., 1991).

METHODS

We questioned the prevalence of nightmares and investigated the possible association with psychopathology and altered daytime functioning for subjects with insomnia as part of a large general population survey concerning sleep disorders.

We hypothesized that insomnia nightmare sufferers experienced more difficulties in daytime functioning and were more likely to have psychiatric disorders than insomnia subjects without nightmares.

A representative sample of 5622 subjects, between 15 and 96 years of age, from the non-institutionalized general population of France, were interviewed by telephone concerning their sleeping habits and sleep disorders.

The interviews were conducted using the Sleep-EVAL System.

Questions investigated nightmares, based on the DSM-IV definition, psychopathological traits, and included 12 other groups of information, including sociodemographics, sleep/wake schedule, daytime functioning, psychiatric and medical history, and drug intake.

The data from 1049 subjects suffering from insomnia were considered for this analysis.

Bivariate analyses, logistic regression analysis using the method of indicator contrasts for the investigation of independent variables, and calculation of significant odds ratios were performed.

RESULTS

Nightmares were reported in 18.3% of the surveyed insomniac population and were two times higher in women than in men.

The following factors were found to be significantly associated with nightmares:

• Sleep with many awakenings,
• abnormally long sleep onset,
• daytime memory impairment following poor nocturnal sleep,
• daytime anxiety following poor nocturnal sleep, and
• being a woman.

There was a strong association between the report of nightmares in women and the presence of either a Depressive Disorder, Anxiety Disorder or both disorders together.

When the effects of major psychiatric disorders were controlled for, nightmares were significantly associated with being a woman, feeling depressed after a poor night's sleep and complaining of a long sleep latency.

Nightmares can lead to a negative conditioning toward sleep and to chronic sleep complaints.

Considering the frequency of nightmares in an adult insomniac population, and the significant relationship between nightmares and certain subgroups, nightmares should receive more attention in patients, especially women complaining of disrupted sleep as high rates of psychiatric disorders were found in this specific group.

REFERENCES