Nightmares are intense, emotionally negative mental experiences that usually occur during late-night sleep and result in abrupt awakenings. Questionnaire-based studies have shown that nightmares are related to impaired sleep quality; however, the polysomnographic profile of nightmare subjects has been only scarcely investigated. We investigated the sleep architecture of 17 individuals with frequent nightmares and 23 control subjects based on polysomnographic recordings of a second night spent in the laboratory after an adaptation night. Nightmare subjects in comparison with control subjects were characterized by impaired sleep architecture, as reflected by reduced sleep efficiency, increased wakefulness, a reduced amount of slow wave sleep, and increased nocturnal awakenings, especially from Stage 2 sleep. While these differences were independent of the effects of waking psychopathology, nightmare subjects also exhibited longer durations of REM sleep that was mediated by heightened negative affect. Our results support that nightmares are related to altered sleep architecture, showing impaired sleep continuity and emotion-related increase in REM propensity.
[Show abstract][Hide abstract] ABSTRACT: Aim: In dream content analysis, the use of retrospective questionnaires introduces biases resulting from subjects’memories. The use of rating scales and coding systems can reduce reliability due to evaluator bias and requires the use of judges. We therefore propose the use of a new self-report instrument for evaluating the threatening content of dreams, which is composed of two subscales.
Materials and method: One dream per subject was used from a sample composed of 154 women (mean age = 29.1, SD = 9.1) and 65 men (mean age = 30.7, SD = 9.1). Subjects were volunteers whose first language was Spanish. Weights were calculated for the Social Threats (ST) and Terrifying Threats (TT) subscales, as well as percentiles for their evaluation, and reliability and validity coefficients.
Results: In terms of validity, both STs and TTs had a significant relationship with the anxiety of subjects at the time when they awoke. For this criterion, the Spearman’s Rho correlation was .31 (p<.001) for STs and .26 for TTs (p<.001). Reliability exceeded or approached .80 for both subscales and the two coefficients calculated.
Conclusions: The Dream Content Evaluation Questionnaire (CECS) composed of the ST and TT subscales is a valid and reliable self-report instrument for evaluating the threatening content of dreams.
[Show abstract][Hide abstract] ABSTRACT: Nightmares are disturbing mental experiences during sleep that usually result in abrupt awakenings. Frequent nightmares are associated with poor subjective sleep quality, and recent polysomnographic data suggest that nightmare sufferers exhibit impaired sleep continuity during nonrapid eye movement (NREM) sleep. Because disrupted sleep might be related to abnormal arousal processes, the goal of this study was to examine polysomnographic arousal-related activities in a group of nightmare sufferers and a healthy control group.
Sleep microstructure analysis was carried out by scoring the cyclic alternating pattern (CAP) in NREM sleep and the arousal index in rapid eye movement (REM) sleep on the second night of the polysomnographic examination.
Hospital-based sleep research laboratory.
There were 17 in the nightmare (NMs) group and 23 in the healthy control (CTLs) group.
The NMs group exhibited reduced amounts of CAP A1 subtype and increased CAP A2 and A3 subtypes, as well as longer duration of CAP A phases in comparison with CTLs. Moreover, these differences remained significant after controlling for the confounding factors of anxious and depressive symptoms. The absolute number and frequency of REM arousals did not differ significantly between the two groups.
The results of our study indicate that NREM sleep microstructure is altered during nonsymptomatic nights of nightmares. Disrupted sleep in the NMs group seems to be related to abnormal arousal processes, specifically an imbalance in sleep-promoting and arousing mechanisms during sleep. CITATION: Simor P; Bódizs R; Horváth K; Ferri R. Disturbed dreaming and the instability of sleep: altered nonrapid eye movement sleep microstructure in individuals with frequent nightmares as revealed by the cyclic alternating pattern. 2013;36(3):413-419.
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