Why do some people experience frequent nightmares while others rarely do? A new study suggests that specific psychological traits, particularly thin mental boundaries and a predisposition called nightmare proneness, play a significant role. These findings, published in the journal Dreaming, provide a clearer picture of the psychological factors contributing to disturbing dreams.
Frequent nightmares are strongly linked to some mental health issues. For instance, research indicates that 50%–70% of individuals with post-traumatic stress disorder (PTSD) experience frequent nightmares, as these distressing dreams are a defining symptom of the condition. Similarly, nightmares are notably more common in people with anxiety disorders, depression, and other mood-related conditions, often reflecting heightened emotional distress and dysregulation.
However, nightmares are not limited to those with mental health challenges; they are also prevalent in the general population. Studies suggest that about 4% of individuals experience nightmares frequently, while approximately 40% report occasional nightmares.
“Nightmares are experienced, at least occasionally, by a relatively large number of individuals with and without mental health concerns. Yet, their causes remain mysterious. We have been attempting to understand what the key psychological dispositions are that seem to influence having nightmares,” said study author William Kelly, an associate professor at the University of the Incarnate Word.
The study involved 116 undergraduate psychology students from a university in the United States. Most participants were young adults, with an average age of 20.6 years. The majority identified as Latino (78.4%), while smaller groups identified as Asian, White, or other ethnicities. Participants completed an online survey that included several validated measures related to nightmares and personality traits.
The researchers examined the relationships between nightmare frequency and four dispositions: neuroticism, nightmare proneness, thin psychological boundaries, and sensory processing sensitivity. After accounting for sociodemographic factors, dream recall frequency, and the overlap among the traits, they found that only nightmare proneness and thin psychological boundaries were significant independent predictors of how often participants experienced nightmares.
Nightmare proneness encompasses psychological factors like emotional instability, mood dysregulation, and heightened sensitivity to stress. The researchers suggested that people with high nightmare proneness might experience a process called “concretization,” in which unclear or abstract mental experiences take on more tangible forms, such as vivid and distressing dream imagery. This makes them more likely to transform waking emotional struggles into disturbing dreams. The study reinforced that nightmare proneness is distinct from other traits like neuroticism and thin boundaries, as it remained a significant predictor even when controlling for these factors.
Individuals with thinner boundaries, on the other hand, are characterized by a greater interconnectedness between their emotions, thoughts, and external stimuli. People with thin boundaries might have a heightened susceptibility to experiencing disturbing imagery and emotions during sleep, as they are less able to compartmentalize or filter out these influences. This finding supports the idea that thinner boundaries create a psychological environment where negative mental content can more easily surface as vivid and unsettling dreams.
“It is not ‘abnormal’ to have nightmares,” Kelly told PsyPost. “There do seem to be some dispositions that influence them. In our study, individuals who had nightmares more often also seemed more likely to have thinner divides between various mental experiences, on top of a tendency to more easily have negative emotions and experience them in various forms. It’s as if there is a tendency for an unpleasant mental event to spread across the mind in certain people, like a storm stirring disturbing imagery and emotions in dreams.”
Contrary to expectations, neuroticism—a personality trait often linked to a tendency to experience negative emotions and stress—did not significantly predict nightmare frequency. While neuroticism has been associated with frequent nightmares in prior studies, this relationship appears less robust when other factors like thin boundaries and nightmare proneness are taken into account.
Sensory processing sensitivity, a trait describing heightened responsiveness to internal and external stimuli, also did not independently predict nightmare frequency. Although previous studies have found links between sensory sensitivity and distressing dreams, this study did not replicate those results. The researchers proposed that the brief measure used in the study may have overlooked critical subcomponents of sensory sensitivity, such as low sensory thresholds, which have shown stronger connections to nightmares in past research.
“We were surprised that sensory processing sensitivity did not relate to nightmares as it did in previous studies, and it would seem to fit well with thin mental boundaries,” Kelly said. “We don’t understand this finding as yet.”
As with all research, there are some limitations. First, the sample consisted primarily of young college students, which may limit the generalizability of the findings to other age groups or populations. Second, the measures used to assess psychological boundaries and sensory processing sensitivity were relatively brief. Longer, more nuanced measures might provide a deeper understanding of how these traits influence nightmares.
Despite these limitations, the study contributes to a growing body of research exploring the psychological traits that predispose individuals to nightmares. By identifying thin psychological boundaries and nightmare proneness as significant predictors, the findings offer valuable insights into the mental processes that shape our dream experiences.
The researchers hope to build on this work by investigating how these traits interact with other mental functions and by examining their impact on different populations. Ultimately, this line of research could inform strategies to reduce nightmare frequency and improve sleep quality for individuals prone to distressing dreams.
“We want to extend these findings and better understand how thinner mental boundaries and the broad nightmare proneness variables are connected to nightmares,” Kelly said. “We are planning additional studies to untangle this.”
“These findings fit into a series of studies we have done to understand how mental functions and traits influence or allow the occurrence of nightmares among individuals who don’t necessarily have serious mental health concerns,” he added. “For instance, nightmares are related more to trait-like dispositions than temporary states and to ego functions, which are the ways the mind regulates itself.”
The study, “An Empirical Comparison of Some Nightmare Dispositions: Neuroticism, Nightmare Proneness, Thin Psychological Boundaries, and Sensory Processing Sensitivity,” was authored by William E. Kelly and John R. Mathe.
