Psychiatrists have identified several common causes of unpleasant dreams.
Oxford researchers surveyed 846 people and concluded that nightmares are associated not only with general level of anxiety, but also with the duration of sleep. Those who sleep for more than nine hours straight are more likely to experience terrible dreams. Alcohol consumption and physical activity, on the contrary, turned out to be "innocent."
According to the authors of the work, nightmares are most often studied as a symptom of post-traumatic stress disorder - a condition that occurs after severe traumatic situations. It is often diagnosed in war veterans or in people with long-term illnesses.
The new work is devoted to the study of the characteristics of nightmares in the general population.
The research was conducted in the form of an online survey. Scientists have developed a "scale of severity of nightmares" (Nightmare Severity Scale). It included questions about the frequency of nightmares over the past two weeks, how frightening the dreams were, and how much they interfered with the person's focus on daytime activities. The survey also used the existing DASS scale for depression, anxiety and stress. In addition, all survey participants completed a questionnaire identifying the presence of post-traumatic stress disorder.
The aim of the study was to identify the most common causes of nightmares. The final test included questions about how often people have experienced stress recently and with what types of events it was associated. Participants were also asked about their level of anxiety in various situations, about the average duration of sleep, the incidence of insomnia, experience of hallucinations or depersonalization (self-perception disorders). Separate questions were devoted to physical activity and alcohol consumption.
Scientists concluded that most often nightmares are accompanied by a high level of anxiety, as well as depersonalization and hallucinations. The link between nightmares and longer sleep was surprising. This relationship persisted regardless of the level of stress in life and the presence of post-traumatic stress disorder. According to the authors of the article, long sleep implies an increase in the number and duration of REM sleep cycles. It is believed that the most memorable dreams we see during the last cycles of this phase.
The authors believe that further research on sleep patterns in the general population is needed. According to them, the study had a number of serious limitations. For example, the very format of the online survey on dreams and nightmares could have attracted mainly those with sleep problems.
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The research is published in the journal Social Psychiatry and Psychiatric Epidemiology.
Natalia Pelezneva
