In the middle of a pleasant dream, something lurks in the shadows. Soon, the nonsensical reverie takes a dark turn and something starts stalking you. What is it? You wake, heart racing, breathing rapidly. That nightmare felt horrible, but was the terrible creature haunting your dream a masked killer or just your mom criticizing your clothing?
The answer depends on your gender.
Geneviève Robert and Antonio Zadra, researchers from the University of Montreal, asked more than 550 subjects to keep dream journals for two to five consecutive weeks, resulting in the records of a total of 9796 dreams. The researchers then analyzed the dreams, finding that of the almost 10,000 dreams, there were 431 bad dreams—which cause some unpleasant feelings—and 253 nightmares, which include an emotion so disagreeable that it wakes people from sleep. Subjects said that nightmares felt more “emotionally intense” than bad dreams.
“[N]ightmares were more bizarre and contained substantially more aggressions, failures, and unfortunate endings,” the study says. Only 331 of the participants experienced unpleasant dreams. They found that 35 percent of nightmares and 55 percent of bad dreams involved emotions other than fear.
After looking at the nightmares for general content, the researchers looked at more specific themes and found the stuff of nightmares varied by gender. Women had nightmares that focused on interpersonal strife—a fight with a partner, a disagreement with a mother-in-law, a conflict with a willful child. The emotions involved in those nightmares included feelings of humiliation, inadequacy, and frustration.
Men, on the other hand, tended to have nightmares about natural disasters (floods, earthquakes, fires and volcanoes), chases, and bugs. The women’s nightmares frequently involved a friend or family member trying to navigate the scary situation with them, while the men worked alone in their nightmares. On average, they found that women experienced more nightmares than men.
“The results have important implications on how nightmares are conceptualized and defined," the researchers wrote, "and support the view that, when compared to bad dreams, nightmares represent a somewhat rarer—and more severe—expression of the same basic phenomenon.”