According to a new study by researchers at the University of Montreal, nightmares have greater emotional impact than bad dreams do, and fear is not always a factor. In fact, it is mostly absent in bad dreams and in a third of nightmares. What is felt, instead, is sadness, confusion, guilt, disgust, etc. For their analysis of 253 nightmares and 431 bad dreams, researchers obtained the narratives of nearly 10,000 dreams. “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,” write Geneviève Robert and Antonio Zadra, psychology researchers at the Université de Montréal, in the last issue of Sleep.