Black people, women and younger adults experience trauma-based nightmares more often than other groups, according to a new epidemiological analysis.

The study, published April 29 in Sleep Medicine, fills a gap in prevalence data on disturbing dreams, which are understood to be common but haven't been broadly analyzed outside of clinical, treatment-seeking populations, said Courtney B. Worley, a researcher and psychologist with the University of Alabama and the study's lead and corresponding author. 

"In my clinical work, I treat survivors of trauma, and I see so many of them struggling with dreams that mess up their functioning," she told The Academic Times. "It creates a lot of distress. And we know that people don't report their dreams to health care providers, because they don't think anything can be done about disturbing dreams." 

The findings are based on a sample of more than 20,000 U.S. adults who participated in the Collaborative Psychiatric Epidemiology Surveys, a series of large epidemiological surveys conducted between 2001 and 2003, with a special emphasis on minority groups. Given the lack of prevalence data on disturbing dreams in the U.S. population, the surveys' highly representative sampling and the "robustness of the dataset [were] too good to pass up," despite the data being nearly two decades old, Worley said. 

The researchers sorted the disturbing dreams into three categories — dreams of the worst event, dreams of trauma and dreams of separation from a loved one. Participants who reported experiencing a traumatic event were asked several follow-up questions, including whether they were having dreams of "the worst event."

"The worst event is what we call the index trauma — the event that bothers them the most, that comes up the most often when they don't want to think about it," Worley said. "This worst dream is the one that would fall most closely under our DSM criteria for trauma." Dreams of trauma, on the other hand, are defined in the study as dreams relating to secondary traumas — in other words, based on traumas separate from the index trauma. 

About 7.2% of the study's respondents reported repeatedly experiencing disturbing dreams of their worst event, with about 2% reporting dreams of trauma and about 1.7% reporting dreams of separation. These experiences could present as "historical dreams" that more or less replay the event like a movie, or symbolic dreams that may not visually represent the event at all. 

"They often have the same theme or emotion and may incorporate other aspects of the person's life," Worley said of symbolic dreams. "Somebody who has combat trauma may replay that firefight in a historical dream, whereas the same firefight exposure in somebody else might result in a symbolic dream, where they have the same feelings of loss of control or fear, but it just plays out a little bit differently." 

The analysis also shows that women suffer from disturbing dreams more frequently than men — roughly 8.5% versus 4.3% — and that such dreams are more prevalent among younger adults than older ones. Both findings confirm existing literature, but with a more diverse sample. "We were surprised that middle-age adults also had a higher prevalence of disturbing dreams than older adults," Worley said. "They still happen in older adulthood, but they seem to be more common in younger and middle-age adults as we reflect on this sample." 

The apparent difference between sexes in frequency of disturbing dreams narrows with age, she added, but the discrepancy is significant in younger people. "It could be that more young women are exposed to trauma," she said. 

Worley speculated as to why younger people are more susceptible to disturbing dreams, emphasizing that she and her colleagues did not test a specific hypothesis. "It could be that younger adults and middle-aged adults are closer to their trauma exposures, or that older adults have learned to adapt and have had more opportunities to resolve those trauma-based dreams," she said. 

The researchers also found that 11.2% of Black respondents reported dreams of the worst event, aligning with higher rates of PTSD among Black people than have been observed in separate studies. People of Filipino, Vietnamese or Chinese descent reported the lowest rates of disturbing dreams. "Maybe there's something different about the individual or cultural factors that influence how these disturbing dreams are experienced and reported," Worley said. "There's a lot more research that needs to be done in order to understand why these differences exist." 

Worley believes the highest value of her research is highlighting that disturbing dreams occur across a broad swath of American adults. She hopes that people suffering from nightmares will realize they are a common phenomenon — and will overcome stigma and embarrassment to talk to their health care providers about evidence-based treatments, such as cognitive processing, exposure and image-rehearsal therapies. 

"My experience with people coming in for treatment is that in four to six sessions we can really make some change in the frequency and intensity of their nightmares and help people sleep better," she said.

The study, "Epidemiology of disturbing dreams in a diverse U.S. sample," published April 29 in Sleep Medicine, was authored by Courtney B. Worley, University of Alabama; Courtney J. Bolstad, Mississippi State University; and Michael R. Nadorff, Mississippi State University and Baylor College of Medicine.