This research, conducted at Université de Montréal in Quebec, involved 572 co-ed volunteers. They were told to keep records of dreams, whether good or bad, for a period between two and five weeks, according to Michael J. Breus, Ph.D., for Psychology Today.

“The reports included details about dreams’ narratives, the emotions present and their level of intensity, as well as the presence of sleep terrors -- brief, highly intense periods of fright during dreams, that are often accompanied by actual screaming or movement like sleepwalking. Researchers considered episodes of sleep terrors to be distinct from nightmares,” according to Breus.

Researchers were able to obtain almost 10,000 dream reports -- of which 431 were identified as bad dreams, and 253 were identified as nightmares.

“Researchers used the result of waking from the dream as the distinguishing characteristic between bad dreams and nightmares; nightmares resulted in awakenings, and bad dreams did not,” Breus says. 

Themes were picked in which volunteers could categorize their dreams, including physical aggression, being chased, interpersonal conflicts, accidents, failures and helplessness, evil presences, disasters and calamities, apprehension, worry and health concerns. “They also established emotional categories to further define dream content, including fear, anger, sadness, confusion, disgust, guilt, and frustration. Researchers used scales of both rationality and ‘everydayness’ to evaluate levels of bizarreness in disturbed dreams.” 

The findings were more than interesting. For starters, bad dreams were more common than nightmares. Nightmares comprised nearly 3 percent of the 9,796 dreams, and bad dreams accounted for 10.8 percent, according to Breus.