Cauchemars et mauvais rêves : impact différentiel des méthodes de collecte et analyse descriptive de leur contenu
The overall goal of this thesis was to further our understanding on disturbed dreaming (bad dreams and nightmares) along two main lines of inquiry. First, we examined the methodological implications associated with the different instruments used to measure dream recall frequency (articles 1 and 2). Second, we investigated the actual content of disturbing dreams, a dimension for which empirical data remain surprisingly scarce (article 3).  Study 1 compared the frequency of nightmares and bad dreams obtained with retrospective methods and with two types of prospective instruments (narrative and checklist logs) in 411 participants. In addition to replicating findings showing that when compared to daily logs, retrospective self-reports underestimate current nightmare and bad dream frequency, we showed that these frequencies were not differentially affected by the type of prospective log. Our second study extended these findings by comparing the differential effects of narrative and checklist logs on general dream recall in 358 participants. The results indicate that checklist logs yield higher prospective dream recall frequency than narrative logs, and that prospectively measured dream recall frequency tends to peak at the beginning of the log and then remains stable over time. Thus, improved dream recall arising from subjects' increased attention towards their dreams is short-lived and the effect quickly offset by motivational factors. Our third article presents a comprehensive and comparative description of the content of 431 bad dreams and 253 nightmares collected prospectively from 331 participants. The results indicate that although nightmares and bad dreams share many content characteristics and features, they also differ along several dimensions: nightmares tend to involve physical threats whereas psychological threats predominate in bad dreams; nightmares are more likely than bad dreams to contain fear as their principal emotion as well as being significantly more emotionally intense; and when compared to bad dreams, nightmares are more bizarre and contain significantly more aggressions, failures, and unfortunate endings. Taken together these findings support the view that nightmares represent a more intense expression of the same basic phenomenon and that this intensity manifests itself along a number of content dimensions. These results are discussed in relation to different theories on the etiology and function of dreams.
Nightmares Bad dreams Dream content Dream recall Dream recall frequency