This consensus paper provides an overview of the state of the art in research on the aetiology and treatment of nightmare disorder and outlines further perspectives on these issues. It presents a definition of nightmares and nightmare disorder followed by epidemiological findings, and then explains existing models of nightmare aetiology in traumatized and non‐traumatized individuals. Chronic nightmares develop through the interaction of elevated hyperarousal and impaired fear extinction. This interplay is assumed to be facilitated by trait affect distress elicited by traumatic experiences, early childhood adversity and trait susceptibility, as well as by elevated thought suppression and potentially sleep‐disordered breathing. Accordingly, different treatment options for nightmares focus on their meaning, on the chronic repetition of the nightmare or on maladaptive beliefs. Clinically, knowledge of healthcare providers about nightmare disorder and the delivery of evidence‐based interventions in the healthcare system is discussed. Based on these findings, we highlight some future perspectives and potential further developments of nightmare treatments and research into nightmare aetiology.

Nightmares are extremely dysphoric dreams. But nightmare distress, and not the mere frequency of nightmares, is associated with well-being and psychopathology. Nightmare distress has been conceptualized in different ways: (a) nightmare intensity, (b) nightmare effects, (c) nightmare related symptoms, and (d) the perception of nightmare distress. The Nightmare Distress Questionnaire (NDQ) is the most often used questionnaire to capture nightmare distress. However, there is insufficient information about its psychometric properties and it remains unclear what exactly it measures. In order to investigate the psychometric quality and factorial structure of this questionnaire, 213 men and women suffering from recurrent nightmares filled in the German version of the NDQ, as well as depression (Center for Epidemiologic Studies Depression Scale, CES-D) and sleep quality (Pittsburgh Sleep Quality Inventory, PSQI) measures. The reliability of the NDQ was good (␣ ϭ .80). We identified 3 subscales, which explained 52% of the total variance: (a) general nightmare distress, (b) impact on sleep, and (c) impact on daytime reality perception. We found moderate correlations between nightmare distress scores, nightmare frequency, depression, and sleep quality. The psychometric properties of the NDQ are good. The questionnaire captures the general perception whether nightmares are evaluated as distressing, as well as nightmare related symptoms.

Current sport-scientific studies mostly neglect the assessment of sleep architecture, although the distribution of different sleep stages is considered an essential component influencing an athlete's recovery and performance capabilities. A mobile, selfapplied tool like the SOMNOwatch plus EEG might serve as an economical and time-friendly alternative to activity-based devices. However, self-application of SOMNOwatch plus EEG has not been validated against conventional polysomnography (PSG) yet. For evaluation purposes, 25 participants (15 female, 10 male; M age = 22.92 ± 2.03 years) slept in a sleep laboratory on two consecutive nights wearing both, conventional PSG and SOMNOwatch plus EEG electrodes. Sleep parameters and sleep stages were compared using paired t-tests and Bland-Altman plots. No significant differences were found between the recordings for Sleep Onset Latency, stages N1 to N3 as well as Rapid Eye Movement stage. Significant differences (Bias [95%-confidence interval]) were present between Total Sleep Time (9.95 min [−29.18, 49.08], d = 0.14), Total Wake Time (−13.12 min [−47.25, 23.85], d = −0.28), Wake after Sleep Onset (−11.70 min [−47.25, 23.85], d = −0.34) and Sleep Efficiency (2.18% [−7.98, 12.34], d = 0.02) with small effect sizes. Overall, SOMNOwatch plus EEG can be considered a valid and practical self-applied method for the examination of sleep. In sport-scientific research, it is a promising tool to assess sleep architecture in athletes; nonetheless, it cannot replace in-lab PSG for all clinical or scientific purposes.

Background: Nightmares are extremely dysphoric dreams, which are prevalent and associated with psychological strain. This study investigated (a) the efficacy of an internet-based imagery rehearsal therapy (IRT), (b) the role of imagery rescription, and (c) the role of guidance during internet-based IRT. Methods: A total of 127 patients suffering from mainly idiopathic nightmares were randomly assigned to 1 of 2 IRT internet-based groups (guided IRT; unguided IRT) or to 1 of 2 active control groups (frequency control group; narrative control group). Results: IRT was more effective than a nightmare frequency control condition with respect to nightmare frequency and nightmare distress. Compared to the narrative control group, IRT was only superior in improving nightmare distress but not in nightmare frequency because the narrative control group also improved regarding nightmare frequency. Guidance by a nightmare coach did not affect efficacy, compliance, or dropout. Conclusion: Internet-based IRT seems to be an effective treatment even when offered with minimal guidance by a nightmare coach. Describing the nightmare narrative in detail already decreased nightmare frequency. However, with regard to inducing decreases in nightmare frequency and nightmare distress, IRT was superior to the narrative control group. The results are discussed with reference to the mastery hypothesis.

Zusammenfassung. Theoretischer Hintergrund: Die Pre-Sleep Arousal Scale (PSAS) gilt als Goldstandard zur Erfassung kognitiver und körperlicher Erregung in der Phase vor dem Einschlafen. Fragestellung: Bestimmung der Gütekriterien der deutschen Übersetzung. Methode: Die 16 übersetzten Items wurden 268 überwiegend studentischen Versuchspersonen vorgelegt, um dimensionale Struktur, Reliabilität und Validität des Fragebogens zu überprüfen. Ergebnisse: Die zweidimensionale Struktur der Originalversion konnte repliziert werden, allerdings empfiehlt es sich, Item 16 aus dem Itempool auszuschließen. Die interne Konsistenz ist gut bis sehr gut. Bezüglich der Validität eigneten sich beide Skalen zur Diskriminierung zwischen guten und schlechten Schläfern und waren beide erwartungsgemäß stärker mit Einschlaf- als mit Durchschlafproblemen assoziiert. Schlussfolgerung: Mit der deutschen Übersetzung der PSAS kann kognitive und körperliche Erregung ökonomisch, reliabel und valide erfasst werden.