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A new study published in the Journal of Sleep Research seeks to determine the relationship between nightmares, fear of sleep, before sleep biological and cognitive arousal, daily stress, and quality of sleep. The 30-day longitudinal study of women with chronic nightmares revealed that participants who expressed greater fear of sleep and impaired sleep reported more nightmares.

However, unexpectedly, biological or cognitive arousal before sleep appeared to be unrelated to nightmares. In addition, there was significant variation among participants, leaving researchers to conclude that further research into potential subgroups of nightmare sufferers may result in a greater understanding of both the origins and consequences of nightmares.

Nightmares, usually a phenomenon of childhood, are frightening dreams that result in both awakening and memory of the dream. When nightmares are consistent and repetitive and continue into adulthood, they can affect the quality of life. Nightmares are also a common symptom for those who have PTSD.

Prior research has investigated the relationship a single factor may have with nightmares; for example, fear or sleep or pre-sleep arousal were found to be related to nightmares as an individual factor. Britta Dumser and colleagues hoped to design a study examining the interaction of multiple factors and their relationship to nightmares.

The research team, “investigated the dynamic interplay of nightmares with fear of sleep, pre-sleep arousal, daily stress, and aspects of sleep disturbances in a sample of regular nightmare sufferers. Intensive, long-term assessments were used, where participants reported nightmares and other factors every day for 30 days. This approach allowed us to estimate the within-person associations between the variables and to explore the proximate factors that have a unique effect on nightmares after controlling for the other factors.”

Participants for the study were found via flyers distributed on the University of Munich Campus. The flyers were provided to psychology students, and those who reported a mental illness or sleep disorder were excluded from participating. The resulting sample was 16 women with an average age of 23 years.

Subjects filled out assessments for insomnia, nightmares, PTSD, and depression. The study then moved to an at-home report system. For 30 days, participants were to report total sleep time, time in bed, nightmare occurrence, nightmare distress, fear of sleep, and pre-sleep arousal. Subjects also wore an actigraph (a device to objectively assess sleep quality) on their wrist every night for 30 days.

Statistical analysis of the collected data found the fear of sleep to be the strongest predictor of nightmare distress. “Our results suggest that fear of sleep paves
the way for higher nightmare distress. This association could be due to a self-fulfilling prophecy on both physiological and psychological levels,” the study authors wrote.

The research team felt that fear of sleep might be related to other maladaptive sleep behaviors like delaying sleep that may also contribute to the likelihood that a distressful nightmare may occur. Sleep quality was the next variable related to both cause and effect of nightmares. Pre-sleep arousal and daily stress appeared unrelated to the presence of nightmares.

The research team acknowledged that the study has some limitations. The first is the small, homogenous sample size. Sixteen women in their early 20s may not represent the experiences of many. Second, the daily assessments of the variables of interest were short to encourage compliance. This may have limited the amount of relevant information collected.

These limitations do not diminish the benefit of the longitudinal nature of the study; earlier research had not collected as much post-sleep data. The collected data over 30 days revealed the individual variation in the antecedents and consequences of nightmares. The research team felt this was a valuable finding for future research.

Dumser and team concluded, “We therefore encourage future within-person research on more specific samples (i.e., patients with diagnosed PTSD vs. insomnia vs. depression vs. non-clinical samples, thus incorporating information on idiographic vs. posttraumatic nightmares) to disentangle these individual differences, identifying possible moderators and subgroups suffering from nightmare distress and fear of sleep.”

The study, “Symptom dynamics among nightmare sufferers: An intensive longitudinal study“, was authored by Britta Dumser, Gabriela G. Werner, Thomas Ehring, and Keisuke Takano.

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