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Background Frequent nightmares show signs of hyperarousal in NREM sleep. Nevertheless, idiopathic nightmare disorder is considered a REM parasomnia, but the pathophysiology of REM sleep in relation to frequent nightmares is controversial. Cortical oscillatory activity in REM sleep is largely modulated by phasic and tonic REM periods and seems to be linked to different functions and dysfunctions of REM sleep. Here, we examined cortical activity and functional synchronization in frequent nightmare recallers and healthy controls, during phasic and tonic REM. Methods Frequent nightmare recallers (N = 22) and healthy controls (N = 22) matched for high dream recall spent two nights in the laboratory. Phasic and tonic REM periods from the second nights’ recordings were selected to examine differences in EEG spectral power and weighted phase lag index (WPLI) across groups and REM states. Results Phasic REM showed increased power and synchronization in delta and gamma frequency bands, whereas tonic REM featured increased power and synchronization in the alpha and beta bands. In the theta band, power was higher during tonic, and synchronization was higher during phasic REM sleep. No differences across nightmare and control participants or patterns representing interactions between the groups and REM microstates emerged. Conclusions Our findings do not support the idea that abnormal REM sleep power and synchronization play a role in the pathophysiology of frequent nightmares. Altered REM sleep in nightmare disorder could have been confounded with comorbid pathologies and increased dream recall, or might be linked to more specific state factors (nightmare episodes).

Imagery rescripting (IR) and imaginal exposure (IE) are two efficacious treatments for nightmare disorder, but their discrete underlying mechanism(s) remain largely unknown. We therefore examined mediators of the treatment effects of IR and IE in a randomized wait-list controlled trial (N = 104). Therapeutic outcomes were assessed at pre- and post-assessment, and mediator assessment took place in between treatment sessions to establish a temporal relationship between mediators and nightmare symptoms (i.e., frequency and distress). In line with the hypothesis, enhanced mastery (or self-efficacy) of the nightmare content mediated the therapeutic efficacy of IR. Furthermore, the treatment effects of IE were mediated by increased tolerability of the negative emotions elicited by nightmares. Even though IR and IE for nightmares seem to produce similar therapeutic effects, the results of this study suggest that IR and IE tap into different underlying processes.

Background: Sleep-disruption is commonly associated with psychotic experiences. Whilst sparse, the literature to date highlights nightmares and related distress as prominent risk factors for psychosis in students. We aimed to further explore the relationship between specific nightmare symptoms and psychotic experiences in university students whilst examining the mediating role of emotion dysregulation. Method: A sample (N=1273) of students respondents from UK Universities completed measures of psychotic experiences, nightmare disorder symptomology, and emotion dysregulation. Findings: Hierarchical linear regression analysis showed that psychotic experiences were significantly associated (Adjusted R2 = 32.4%) with perceived nightmare intensity, consequences and resulting awakenings, and with emotion regulation difficulties. Furthermore, multiple mediation analysis showed that the association between psychotic experiences and nightmare factors was mediated by emotion regulation difficulties. Interpretation: Adaptive regulation of dream content during rapid eye-movement sleep has previously been demonstrated to attenuate surges in affective arousal by controlling the intensity and variability of emotional content. Deficits in emotion regulation may partially explain the experience of more intense and disruptive nightmares amongst individuals with psychotic experiences. Emotion regulation may represent an important control mechanism that safeguards dream content and sleep quality. Funding Statement: The authors stated: "No funding received." Declaration of Interests: No conflicts of interest declared in relation to this paper. Ethics Approval Statement: The study was approved by the Sheffield Hallam University Research Ethics Committee, and all participants provided online informed consent.

This study presents a meta-analysis of the effectiveness of psychological treatments for chronic nightmares using imaginal confrontation with nightmare contents (ICNC) or imagery rescripting and rehearsal (IRR). Pre-post effect sizes (Hedges' g) were calculated for the outcome measures of nightmare frequency, nights per week with nightmares, sleep quality, depression, anxiety, and PTSD severity. Fixed-effects and random-effects models were applied. High effect sizes were found for nightmare frequency (g=1.04), nights per week with nightmares (g=0.99), and PTSD severity (g=0.92). Most of the effect sizes for the secondary outcomes were moderate. One objective was to clarify whether ICNC or IRR is more important for nightmare reduction. The results indicate that a higher duration of time for ICNC is associated with greater improvements: The minutes of applied ICNC moderate the effect sizes for nightmare frequency at follow-up 2 and for nights per week with nightmares at post and follow-up 1. The percentage of applied ICNC moderates the effect sizes for nightmare frequency and nights per week with nightmares at follow-up 1. Thus, dismantling studies are necessary to draw conclusions regarding whether ICNC or IRR is the most effective in the psychological treatment of chronic nightmares.

Nightmares are a common and serious problem in psychotherapeutic practice, although they are seldom considered as independent mental disorders. There are some promising approaches to the treatment of nightmares, notably Imagery Rehearsal Therapy, a cognitive-restructuring treatment. The core of this approach is the modification of the nightmare script and repeated imagination of the new script. However, most evaluation surveys have been conducted only with trauma patients, and thus far there is no standardized manual in the German language. 69 participants were examined using self-rating questionnaires. Participants belonged to three groups: 22 primarily nightmare sufferers, 21 patients with major depression and nightmares, 26 with PTSD and nightmares. 12 of the PTSD patients were randomly assigned to a control condition. Primary outcome measures were nightmare frequency and anxiety during nightmares. Overall, nightmare frequency and the anxiety they caused decreased following the treatment. Nightmare frequency and anxiety during the nightmares were highest in the PTSD group initially. Nightmare frequency decreased in all groups. Anxiety scores decreased least in PTSD patients, in depressive patients and primarily nightmare sufferers anxiety scores decreased during intervention. In primarily nightmare sufferers anxiety remained low up to the catamnesis period as well. Thus, those who suffered primarily from nightmares showed the strongest benefit from the nightmare treatment.

The American Academy of Sleep Medicine’s International Classification of Sleep Disorders (ICSD-II) defines parasomnias as “undesirable physical events or experiences that occur during entry into sleep, within sleep or during arousals from sleep.” Depending on their exact manifestations, frequency, and intensity, parasomnias can be considered normal sleep phenomena and may not significantly affect sleep quality or quantity or daytime functioning. In some cases, however, episodes can lead to self-injuries, psychological distress, and sleep disruption, thereby seriously affecting the patient as well as family members. Parasomnias are classified into 3 categories: (1) parasomnias associated with non–rapid eye movement (NREM) sleep (eg, sleepwalking and sleep terrors), (2) parasomnias associated with rapid eye movement (REM) sleep (eg, nightmare disorder and REM sleep behavior disorder [RBD]), and (3) other parasomnias (eg, sleep enuresis and sleep-related groaning). This article focuses on diagnostic considerations of 2 prototypic NREM sleep parasomnias, namely, sleepwalking (somnambulism) and sleep terrors. Together with confusional arousals, sleepwalking and sleep terrors are collectively termed disorders of arousal because of the autonomic and motor arousal that drives the patient toward a state of partial wakefulness fromsleep. A summary

Nightmares are a prevalent parasomnia associated with a range of psychiatric conditions and pathological symptoms. Current knowledge about how nightmares are produced is still influenced by neo-psychoanalytic speculations as well as by more recent personality, evolutionary and neurobiological models. A majority of these models stipulate some type of emotionally adaptive function for dreaming, e.g., image contextualization, affect desomatization, mood regulation or fear extinction. Nightmares are widely seen to be either an intensified expression of an emotionally adaptive function or, conversely, as evidence of its breakdown. Our recent, affective network dysfunction (AND) model, integrates the tenets of many prior models in proposing that nightmares reflect problems with the fear extinction function of dreaming. This new model accounts for a wide range of dysphoric dream imagery (bad dreams, idiopathic nightmares, post-traumatic nightmares) and incorporates recent findings in the areas of brain imaging, sleep physiology, PTSD, anxiety disorders and the consolidation and extinction of fear memories.

Sexual assault survivors with post-traumatic stress disorder (PTSD) were assessed for frequency of nightmares, measured retrospectively on the Nightmare Frequency Questionnaire (NFQ) and prospectively on nightmare dream logs (NLOG). Retrospective frequency was extremely high, averaging occurrences every other night and an estimated number of nightmares greater than five per week. Test-retest reliability data on the NFQ yielded weighted kappa coefficients of .85 (95% CI, .74-.95) for nights and .90 (95% CI, .83-.97) for nightmares. Correlations between retrospective and prospective nightmare frequencies ranged between .53 (P = .001) for nights and .63 (P = .001) for nightmares. Correlations between frequency and distress measures (anxiety, depression, post-traumatic stress) yielded coefficients ranging from (r = .28-.53). Compared with intrusive, cumbersome and time-consuming prospective measurements, the NFQ appears reliable, convenient, and equally useful in assessing nightmare frequency in a group of sexual assault survivors. Nightmare frequency, prevalence, distress and impairment are discussed.

Objectives Nightmares are intense and highly unpleasant mental experiences that occur usually – but not exclusively – during late-night Rapid Eye Movement (REM) sleep and often provoke abrupt awakenings.The underlying mechanism of nightmare disorder was only scarcely investigated and remains poorly understood. The most influential model of nightmare disorder that provided a common framework fortrauma-related and non-traumatic (idiopathic) nightmares was introduced by Levin and Nielsen (2007). One of the main assumptions of the model is that nightmares reflect unsuccessful fear-extinction processes during (REM) sleep due to a dysfunctional brain network comprising fronto-limbic structures. Consequently, amygdalar over-activation and inefficient (prefrontal) inhibition lead to the emotional intensification of dreaming and hyperarousal during sleep. Nevertheless, sleep quality and emotional regulation in nightmare sufferers was mainly examined by questionnaire-based studies. Methods We have performed a series of quantitative EEG analyses based on the polysomnographic data of young (non-ptsd) nightmare sufferers and matched controls. Moreover, in a subsequent study we investigated emotional habituation to arousing images after a night of polysomnographically monitored sleep in a group of nightmare sufferers and matched controls. Emotional reactivity was quantified by subjective evaluations and psychophysiological measures (HRV, SCR). Results In line with questionnaire-based findings, we found that nightmare sufferers are characterized by fragmented sleep, reduced Slow Wave Sleep (SWS), enhanced microarousals during NREM sleep and heightened wake-like oscillations during REM sleep. Furthermore, arousal-related cortical activity coupled with attenuated parasympathetic regulation were evidenced in nightmare sufferers specifically during NREM to REM transitions. Discussion Given that the neural network underlying emotional memory processing is highly active during REM periods, and REM sleep seems to be intimately related to fear memory processing, our findings might indirectly support Levin and Nielsen’s assumption of disrupted REM-dependent fear-extinction in nightmare disorder. Nevertheless, the association between impaired emotional regulation and altered sleep physiology remains to be investigated. Conclusions In our experiments we aimed to directly test Levin and Nielsen’s fear-extintion model of nightmare disorder and to relate impaired emotional regulation to specific sleep EEG features. We conclude that examining nightmare disorder by such integrative approach would shed more light on the enigma of REM sleep and emotional memory processing. Significance Our research could shed more light on the mechanism of nightmare formation, propagate the professional knowledge of nightmare disorder, and facilitate the development of effective, evidence-based treatment procedures.

Background: Nightmares are rare in the sleep laboratory, even in patients with posttraumatic stress disorder for whom nightmare complaints are diagnostic. Nevertheless, it is possible that laboratory conditions do not preclude the observation of telltales—nightmare-related modifications of tonic sleep—given sufficiently large samples. Methods: Sixty-three unmedicated, nonapneic Vietnam combat veterans undergoing inpatient treatment for posttraumatic stress disorder underwent polysomnographic testing and assessment of nightmare complaint. Results: Trauma-related nightmare complaint, but not non–trauma-related complaint, was associated with increased wake-after-sleep-onset in the sleep laboratory. No relationships between nightmare complaint and rapid eye movement sleep architecture were observed. Conclusions: Increased wake-after-sleep-onset was specifically associated with trauma-related nightmare complaint, confirming data from other quarters suggesting they are both phenomenologically and functionally distinct from normal dreaming.

The effectiveness of systematic desensitization in ameliorating nightmares was evaluated in a controlled study. Twenty-nine subjects were assigned to either systematic desensitization, a nightmare discussion placebo, or continuous self-recording. The placebo treatment did not differ from desensitization in terms of rated logicalness and potential effectiveness. However, the desensitization group showed a significantly greater reduction in the frequency of nightmares as well as a decrease in rated intensity. Moreover the desensitization subjects also had a significantly greater decrease in reported fear and state anxiety. Related research on nightmares is noted and future research needs are discussed.

Following an historical and theoretical overview and introduction, reports on the direct psychological treatments of nightmares are reviewed. The majority of the reviewed reports are case studies, although there are several controlled and group studies. Many techniques, including desensitization, operant procedures, hypnosis, analysis, story line alteration, and “face and conquer” approaches were all noted as helpful for some subjects. Advantages and limitations of the different methods, as well as the ways the therapies impact on the anxiety, uncontrollability, perceived importance, or realism of the nightmares, are discussed. The article concludes with suggestions far both the clearer reporting of case studies are for further research.