Content of Nightmares and Bad Dreams Identified in New Study

"I'm in a closet. A strip of white cloth is forcing me to crouch. Instead of clothes hanging, there are large and grotesquely shaped stuffed animals like cats and dogs with grimacing teeth and bulging eyes. They're hanging and wiggling towards me. I feel trapped and frightened."

The above account of a nightmare was one of many recorded by sleep researchers for a new study on the content of nightmares versus bad dreams published in the journal Sleep.

A bad dream and a nightmare can both be unpleasant sleep experiences, but their similarities may end there, according to researchers from the University of Montreal, who differentiated between and studied 253 nightmares and 431 bad dreams out of an analysis that included 10,000 dream records compiled by more than 500 respondents over a two-week period.

The study revealed that while nightmares have a greater emotional impact on a person than a bad dream, fear is not always a factor in nightmares. The researchers contend that fear is mostly absent from bad dreams and not present in two-thirds of nightmares.

"Physical aggression is the most frequently reported theme in nightmares. Moreover, nightmares become so intense they will wake you up. Bad dreams, on the other hand, are especially haunted by interpersonal conflicts," the study authors, Geneviève Robert and Antonio Zadra, psychology researchers at the University of Montreal, said in a joint statement.

"Death, health concerns and threats are common themes in nightmares," Robert said. "But it would be wrong to think that they characterize all nightmares. Sometimes, it is the feeling of a threat or a ominous atmosphere that causes the person to awaken. I'm thinking of one narrative, in which the person saw an owl on a branch and was absolutely terrified."

Robert and Zadra also found that men were more likely than women to have nightmares featuring natural disasters and war. Women were more likely to have nightmares involving themes of interpersonal conflict.

"Nightmares are not a disease in themselves but can be a problem for the individual who anticipates them or who is greatly distressed by their nightmares. People who have frequent nightmares may fear falling asleep - and being plunged into their worst dreams," Zadra said. "Some nightmares are repeated every night. People who are awakened by their nightmares cannot get back to sleep, which creates artificial insomnia."

When asked what we can understand by studying dreams, Zadra said "almost everything," adding that their research further asserts that bad dreams and nightmares are part of the same emotional and neurocognitive process.