A psychophysiological study of nightmares

Association of nightmares with cardio-cerebrovascular disease, hypertension and hyperlipidemia in older adults: A population-based cross-sectional study

OBJECTIVE

This cross-sectional study investigated the relationship of nightmares with cardio-cerebrovascular disease (CVD), hypertension and hyperlipidemia which are major preceding diseases of CVD in older adults.

METHODS

Participants (n = 2824; mean age 63.6 ± 6.6 years, females 49.3%) completed the Disturbing Dream and Nightmare Severity Index (DDNSI), which was used to divide the sample into either the Nightmare or Non-Nightmare group (cut-off score ≥ 10). Demographic information, history of CVD (cerebrovascular disease, myocardial infarction, congestive heart failure, coronary artery disease, and arrhythmia), hypertension, hyperlipidemia, and self-report questionnaires about stress (Perceived Stress Scale), depression (Beck Depression Inventory), sleep quality (Pittsburgh Sleep Quality Index), and insomnia symptoms were also collected.

RESULTS

Among the sample, 379 participants (13.4%) reported experiencing nightmares more than once a year, and 73 participants (2.6%) were classified as having nightmare disorder based on DDNSI scores (≥10). 11.3% of participants (n = 319) reported having more than one CVD. Approximately half of the participants reported a history of hypertension (52.1%, n = 1471) and hyperlipidemia (47.7%, n = 1346). Logistic regression analysis indicated the Nightmare group was 2.04 times at higher risk for hyperlipidemia (OR = 2.04, 95% CI 1.22-3.40, p = .006) after controlling for covariates compared to the Non-Nightmare group. Although non-significant, there was a trend toward a higher risk of hypertension in the Nightmare group (OR = 1.67, 95% CI 0.99-2.84, p = .056).

CONCLUSIONS

Results of this study indicate frequent nightmares in older adults may be associated with hyperlipidemia, which are risk factors for CVD. Further studies are needed to explore nightmares' directionality and health consequences in an aging population.

Short-term stability and night-to-night variability of sleep parameters in nightmares comorbid with chronic insomnia Disorder across multiple nights of polysomnography

STUDY OBJECTIVES

The purpose of this study was to examine the degree of short-term stability of polysomnographic (PSG) measured sleep parameters and the overall differences between individuals with comorbid nightmares and insomnia compared to those with chronic insomnia disorder alone or good sleeping controls across four nights in the sleep lab.

METHODS

A total of 142 good sleeping controls, 126 chronic insomnia alone, and 24 comorbid insomnia/nightmare participants underwent four consecutive nights of 8-hour PSG recordings. Outcomes included sleep continuity, architecture, and REM-related parameters across nights one through four. Intraclass correlation coefficients with mixed-effect variances and repeated-measure analysis of covariance were used, respectively, to determine short-term stability as well as between-participants and time-by-group interaction effects.

RESULTS

Wake after sleep onset and stage 1 showed "poor stability" in the comorbid insomnia/nightmare group compared to "moderate stability" in the good sleeping controls and chronic insomnia alone group. Significant between-group effects (all ps < .05) showed that the comorbid insomnia/nightmare group took longer to fall asleep and had a greater first-night-effect in stage 1 compared to good sleeping controls and chronic insomnia alone group; in addition, the comorbid insomnia/nightmare and insomnia alone groups slept shorter, with fewer awakenings and REM periods, compared to the good sleeping controls.

CONCLUSIONS

Nightmares are associated with abnormal sleep above and beyond REM disruption, as sleep continuity was the primary aspect in which poor stability and group differences emerged. The greater inability to fall asleep and instability of sleep fragmentation in those with comorbid insomnia/nightmares compared to chronic insomnia alone may be attributed to the impact of presleep anticipatory anxiety and nightmare-related distress itself.

CLINICAL TRIAL INFORMATION

The data analyzed in this study does not come from any current or previous clinical trials. Therefore, there is no clinical trial information to report.

Cortical hyperarousal in individuals with frequent nightmares

Nightmares are common among the general population and psychiatric patients and have been associated with signs of nocturnal arousal such as increased heart rate or increased high-frequency electroencephalographic (EEG) activity. However, it is still unclear, whether these characteristics are more of a trait occurring in people with frequent nightmares or rather indicators of the nightmare state. We compared participants with frequent nightmares (NM group; n = 30) and healthy controls (controls; n = 27) who spent 4 nights in the sleep laboratory over the course of 8 weeks. The NM group received six sessions of imagery rehearsal therapy (IRT), the 'gold standard' of cognitive-behavioural therapy for nightmares, between the second and the third night. Sleep architecture and spectral power were compared between groups, and between nights of nightmare occurrence and nights without nightmare occurrence in the NM group. Additionally, changes before and after therapy were recorded. The NM group showed increased beta (16.25-31 Hz) and low gamma (31.25-35 Hz) power during the entire night compared to the controls, but not when comparing nights of nightmare occurrence to those without. Moreover, low gamma activity in rapid eye movement sleep was reduced after therapy in the NM group. Our findings indicate, cortical hyperarousal is more of a trait in people with frequent nightmares within a network of other symptoms, but also malleable by therapy. This is not only a new finding for IRT but could also lead to improved treatment options in the future that directly target high-frequency EEG activity.

Clinical neurophysiology of REM parasomnias: Diagnostic aspects and insights into pathophysiology

Parasomnias are due to a transient unstable state dissociation during entry into sleep, within sleep, or during arousal from sleep, and manifest with abnormal sleep related behaviors, perceptions, emotions, dreams, and autonomic nervous system activity. Rapid eye movement (REM) parasomnias include REM sleep behavior disorder (RBD), isolated recurrent sleep paralysis and nightmare disorder. Neurophysiology is key for diagnosing these disorders and provides insights into their pathophysiology. RBD is very well characterized from a neurophysiological point of view, also thank to the fact that polysomnography is needed for the diagnosis. Diagnostic criteria are provided by the American Academy of Sleep Medicine and video-polysomnography guidelines for the diagnosis by the International REM Sleep Behavior Disorder Study Group. Differences between the two sets of criteria are presented and discussed. Availability of polysomnography in RBD provides data on sleep electroencephalography (EEG), electrooculography (EOG) and electromyography (EMG). Sleep EEG in RBD shows e.g. changes in delta and theta power, in sleep spindles and K complexes. EMG during REM sleep is essential for RBD diagnosis and is an important neurodegeneration biomarker. RBD patients present alterations also in wake EEG, autonomic function, evoked potentials, and transcranial magnetic stimulation. Clinical neurophysiological data on recurrent isolated sleep paralysis and nightmare disorder are scant. The few available data provide insights into the pathophysiology of these disorders, demonstrating a state dissociation in recurrent isolated sleep paralysis and suggesting alterations in sleep macro- and microstructure as well as autonomic changes in nightmare disorder.

The Nightmare Quality of Life Questionnaire

RATIONALE

Patient-centered outcomes are increasingly sought to evaluate social interactions and healthcare interventions in patients with sleep disorders. Yet, measures to assess quality of life (QoL) are lacking for those who experience nightmares.

OBJECTIVE

The aim of the study is to describe the development and validation of a new health-related quality of life (HRQoL) instrument for patients with nightmares.

METHODS

Attributes obtained from a focus group of patients (n = 113) with established nightmares were analyzed using exploratory factor analysis to elicit salient QoL themes for the new instrument. A validation cohort (n = 34) was used to determine the psychometric performance of the 16-item questionnaire including item-scaling, concurrent validity, and test-retest reliability tested four weeks apart.

RESULTS

Four factors (sleep health, emotional and psychological well-being, social interaction, and motivation) explained 53.9% of the total variance. The Nightmare Quality of Life (NQoL) showed good internal consistency (Cronbach's alpha 0.85) and test-retest reliability (ICC = 0.89). Concurrent validity was evidenced by a strong correlation with the Nightmare Distress Questionnaire (r = 0.87; p < .001) and more modest associations with the Nightmare Frequency Questionnaire (r = , 0.69; p < .001), SF-36 (r = -0.68; p < .001), and PSQI (r = 0.45; p = .007).

CONCLUSIONS

The NQoL has demonstrable construct validity and reliability and represents a promising multi-dimensional instrument to assess outcome measures for quality of life in patients with nightmares.

The Relationship between Nightmare Experience and Athletes' Personality Traits and Anxiety

OBJECTIVE

Frequent nightmare behavior or deep nightmare experiences may harm the physical and mental health and performance of athletes. This study explores the nightmare experiences of athletes, and includes non-athletes with similar experiences for comparison.

METHODS

The Nightmare Experience Questionnaire (NEQ); Zuckerman-Kuhlman-Aluja Personality Questionnaire, Shortened Form (ZKA-PQ/SF); and Self-Rating Anxiety Scale (SAS) were used. The subjects were 187 athletes (mean age = 20.44 years, SD = 0.85; 91 females, 96 males) and 90 non-athletes (mean age = 20.34 years, SD = 1.65; 52 females, 38 males) who reported having nightmares.

RESULTS

A total of 87 athletes (46.5%) reported having nightmare experiences. The athlete nightmare group scored significantly higher in neuroticism than the non-nightmare group, and their anxiety scores were significantly higher than those of non-athletes, who scored higher in aggressiveness, neuroticism, and sensation seeking. Moreover, anxiety, neuroticism, and sensation seeking positively predicted athletes' nightmare experiences.

CONCLUSIONS

Personality traits and anxiety levels can be effectively applied to predict athletes' nightmare experiences.

Adaptive Solutions to the Problem of Vulnerability During Sleep

Sleep is a behavioral state whose quantity and quality represent a trade-off between the costs and benefits this state provides versus the costs and benefits of wakefulness. Like many species, we humans are particularly vulnerable during sleep because of our reduced ability to monitor the external environment for nighttime predators and other environmental dangers. A number of variations in sleep characteristics may have evolved over the course of human history to reduce this vulnerability, at both the individual and group level. The goals of this interdisciplinary review paper are (1) to explore a number of biological/instinctual features of sleep that may have adaptive utility in terms of enhancing the detection of external threats, and (2) to consider relatively recent cultural developments that improve vigilance and reduce vulnerability during sleep and the nighttime. This paper will also discuss possible benefits of the proposed adaptations beyond vigilance, as well as the potential costs associated with each of these proposed adaptations. Finally, testable hypotheses will be presented to evaluate the validity of these proposed adaptations.

What about dreams? State of the art and open questions

Several studies have tried to identify the neurobiological bases of dream experiences, nevertheless some questions are still at the centre of the debate. Here, we summarise the main open issues concerning the neuroscientific study of dreaming. After overcoming the rapid eye movement (REM) ‐ non‐REM (NREM) sleep dichotomy, investigations have focussed on the specific functional or structural brain features predicting dream experience. On the one hand, some results underlined that specific trait‐like factors are associated with higher dream recall frequency. On the other hand, the electrophysiological milieu preceding dream report upon awakening is a crucial state‐like factor influencing the subsequent recall. Furthermore, dreaming is strictly related to waking experiences. Based on the continuity hypothesis, some findings reveal that dreaming could be modulated through visual, olfactory, or somatosensory stimulations. Also, it should be considered that the indirect access to dreaming remains an intrinsic limitation. Recent findings have revealed a greater concordance between parasomnia‐like events and dream contents. This means that parasomnia episodes might be an expression of the ongoing mental sleep activity and could represent a viable direct access to dream experience. Finally, we provide a picture on nightmares and emphasise the possible role of oneiric activity in psychotherapy. Overall, further efforts in dream science are needed (a) to develop a uniform protocol to study dream experience, (b) to introduce and integrate advanced techniques to better understand whether dreaming can be manipulated, (c) to clarify the relationship between parasomnia events and dreaming, and (d) to determine the clinical valence of dreams.

The Parasomnias and Sleep Related Movement Disorders—A Look Back at Six Decades of Scientific Studies

The objective of this article is to provide a comprehensive personal survey of all the major parasomnias with coverage of their clinical presentation, investigation, physiopathogenesis and treatment. These include the four major members of the slow-wave sleep arousal parasomnias which are enuresis nocturna (bedwetting), somnambulism (sleepwalking), sleep terrors (pavor nocturnus in children, incubus attacks in adults) and confusional arousals (sleep drunkenness). Other parasomnias covered are sleep-related aggression, hypnagogic and hypnopompic terrifying hallucinations, REM sleep terrifying dreams, nocturnal anxiety attacks, sleep paralysis, sleep talking (somniloquy), sexsomnia, REM sleep behavior disorder (RBD), nocturnal paroxysmal dystonia, sleep starts (hypnic jerks), jactatio capitis nocturna (head and total body rocking), periodic limb movement disorder (PLMs), hypnagogic foot tremor, restless leg syndrome (Ekbom syndrome), exploding head syndrome, excessive fragmentary myoclonus, nocturnal cramps, and sleep-related epileptic seizures. There is interest in the possibility of relationships between sleep/wake states and creativity.

Nightmares in Children with Foetal Alcohol Spectrum Disorders, Autism Spectrum Disorders, and Their Typically Developing Peers

Children with Foetal Alcohol Spectrum Disorders (FASD) and Autism Spectrum Disorders (ASD) experience significantly higher rates of sleep disturbances than their typically developing (TD) peers. Pre-sleep anxiety and waking emotional content is known to affect the content and frequency of nightmares, which can be distressing to children and caregivers. This is the first study to analyse nightmare frequency and content in FASD, and to assess its association with psychometric outcomes. Using online caregiver questionnaires, we assessed reports from 277 caregivers of children with ASD (n = 61), FASD (n = 112), and TD children (n = 104) using the Children's Sleep Habits Questionnaire (CSHQ), the Child Behaviour Checklist (CBCL), the Spence Children's Anxiety Scale (SCAS), and the Behaviour Rating Inventory for Executive Functioning (BRIEF). Within the ASD group, 40.3% of caregivers reported their children had nightmares. Within the FASD group, 73.62% of caregivers reported their children had nightmares, and within the TD group, 21.36% of caregivers reported their children had nightmares. Correlation analysis revealed significant associations between anxiety and nightmares, maladaptive behaviour and nightmares, and executive functioning and nightmares in the TD and FASD groups, but not ASD group. This paper adds to the emerging body of work supporting the need for sleep interventions as part of clinical practice with regard to children with ASD and FASD. As a relatively niche but important area of study, this warrants much needed further research.

Nightmare content during the COVID-19 pandemic: Influence of COVID-related stress and sleep disruption in the United States

Nightmares are often associated with psychiatric disorders and acute stress. This study explores how the COVID-19 pandemic may have influenced the content of nightmares. A sample of N = 419 US adults completed online surveys about sleep and COVID-19 experiences. Participants were asked about the degree to which they agreed with statements linking greater general stress, worse overall sleep and more middle-of-the-night insomnia with the COVID-19 pandemic. They were also asked if, during the pandemic, they experienced nightmares related to various themes. Logistic regression analyses examined each nightmare content as outcome and increased stress, worse sleep and more middle-of-the-night insomnia as predictors, adjusted for age, sex and race/ethnicity. Those who reported greater general COVID-related stress were more likely to have nightmares about confinement, failure, helplessness, anxiety, war, separation, totalitarianism, sickness, death, COVID and an apocalypse. Those who reported worsened sleep were more likely to have nightmares about confinement, oppression, failure, helplessness, disaster, anxiety, evil forces, war, domestic abuse, separation, totalitarianism, sickness, death, COVID and an apocalypse. Those who reported worsened middle-of-the-night insomnia were more likely to have nightmares about confinement, oppression, failure, helplessness, disaster, anxiety, war, domestic abuse, separation, totalitarianism, sickness, death, COVID and an apocalypse. These results suggest that increased pandemic-related stress may induce negatively-toned dreams of specific themes. Future investigation might determine whether (and when) this symptom indicates an emotion regulation mechanism at play, or the failure of such a mechanism.

Altered sleep behavior in a genetic mouse model of impaired fear extinction

Sleep disturbances are a common complaint of anxiety patients and constitute a hallmark feature of post-traumatic stress disorder (PTSD). Emerging evidence suggests that poor sleep is not only a secondary symptom of anxiety- and trauma-related disorders but represents a risk factor in their development, for example by interfering with emotional memory processing. Fear extinction is a critical mechanism for the attenuation of fearful and traumatic memories and multiple studies suggest that healthy sleep is crucial for the formation of extinction memories. However, fear extinction is often impaired in anxiety- and trauma-related disorders-an endophenotype that is perfectly modelled in the 129S1/SvImJ inbred mouse strain. To investigate whether these mice exhibit altered sleep at baseline that could predispose them towards maladaptive fear processing, we compared their circadian sleep/wake patterns to those of typically extinction-competent C57BL/6 mice. We found significant differences regarding diurnal distribution of sleep and wakefulness, but also sleep architecture, spectral features and sleep spindle events. With regard to sleep disturbances reported by anxiety- and PTSD patients, our findings strengthen the 129S1/SvImJ mouse models' face validity and highlight it as a platform to investigate novel, sleep-focused diagnostic and therapeutic strategies. Whether the identified alterations causally contribute to its pathological anxiety/PTSD-like phenotype will, however, have to be addressed in future studies.

Effects of nightmares on the cortisol awakening response: An ambulatory assessment pilot study

Previous studies have reported an association between sleep-related factors such as sleep duration, sleep quality and time of awakening with the cortisol awakening response (CAR). Preliminary evidence suggests that frequent nightmares are associated with a blunted CAR. In the present pilot study we investigated the effect of acute nightmares on the CAR and the cortisol profile of the subsequent day using a within-subject ambulatory assessment study design. Thirty healthy volunteers who reported frequent nightmares enrolled in the study. Over a period of 14 days, salivary samples in addition to sleep-related and state variables were collected at home over the day. Salivary profiles of free cortisol and alpha amylase for up to two days following a nightmare were compared to those following a neutral dream. Overall, mood and health were decreased and the CAR was elevated following nightmares compared to neutral dreams. No differences were found for alpha amylase and for all variables over the remaining part of the day. Results suggest that sleep-related factors such as the occurrence of nightmares account for a certain amount of variance observed in the CAR. This has important methodological implications for CAR studies in general and might have even more relevance for studies in clinical populations suffering from chronic sleep disturbances.

Dream engineering: Simulating worlds through sensory stimulation

We explore the application of a wide range of sensory stimulation technologies to the area of sleep and dream engineering. We begin by emphasizing the causal role of the body in dream generation, and describe a circuitry between the sleeping body and the dreaming mind. We suggest that nearly any sensory stimuli has potential for modulating experience in sleep. Considering other areas that might afford tools for engineering sensory content in simulated worlds, we turn to Virtual Reality (VR). We outline a collection of relevant VR technologies, including devices engineered to stimulate haptic, temperature, vestibular, olfactory, and auditory sensations. We believe these technologies, which have been developed for high mobility and low cost, can be translated to the field of dream engineering. We close by discussing possible future directions in this field and the ethics of a world in which targeted dream direction and sleep manipulation are feasible.

Sleep disturbance in PTSD and other anxiety-related disorders: an updated review of clinical features, physiological characteristics, and psychological and neurobiological mechanisms

The current report provides an updated review of sleep disturbance in posttraumatic stress disorder and anxiety-related disorders. First, this review provides a summary description of the unique and overlapping clinical characteristics and physiological features of sleep disturbance in specific DSM anxiety-related disorders. Second, this review presents evidence of a bidirectional relationship between sleep disturbance and anxiety-related disorders, and provides a model to explain this relationship by integrating research on psychological and neurocognitive processes with a current understanding of neurobiological pathways. A heuristic neurobiological framework for understanding the bidirectional relationship between abnormalities in sleep and anxiety-related brain pathways is presented. Directions for future research are suggested.

Cortical hyperarousal in NREM sleep normalizes from pre- to post- REM periods in individuals with frequent nightmares

Study Objectives

Frequent nightmares have a high prevalence and constitute a risk factor for psychiatric conditions, but their pathophysiology is poorly understood. Our aim was to examine sleep architecture and electroencephalographic markers—with a specific focus on state transitions—related to sleep regulation and hyperarousal in participants with frequent nightmares (NM participants) versus healthy controls.

Methods

Healthy controls and NM participants spent two consecutive nights in the sleep laboratory. Second night spectral power during NREM to REM sleep (pre-REM) and REM to NREM (post-REM) transitions as well as during NREM and REM periods were evaluated for 22 NM participants compared to 22 healthy controls with a similar distribution of age, gender, and dream recall frequency.

Results

We found significant differences between the groups in the pre-REM to post-REM changes in low- and high-frequency domains. NM participants experienced a lower amount of slow-wave sleep and showed increased beta and gamma power during NREM and pre-REM periods. No difference was present during REM and post-REM phases. Furthermore, while increased pre-REM high-frequency power seems to be mainly driven by post-traumatic stress disorder (PTSD) symptom intensity, decreased low-frequency activity occurred regardless of PTSD symptom severity.

Conclusion

Our findings indicate that NM participants had increased high-frequency spectral power during NREM and pre-REM periods, as well as relatively reduced slow frequency and increased fast frequency spectral power across pre-and post-REM periods. This combination of reduced sleep-protective activity and increased hyperarousal suggests an imbalance between sleep regulatory and wake-promoting systems in NM participants.

Trauma Associated Sleep Disorder: Clinical Developments 5 Years After Discovery

PURPOSE OF REVIEW

We review recent and growing evidence that provides support for a novel parasomnia, trauma associated sleep disorder (TASD). Based on these findings, we further develop the clinical and polysomnographic (PSG) characteristics of TASD. We also address factors that precipitate TASD, develop a differential diagnosis, discuss therapy, and propose future directions for research.

RECENT FINDINGS

Nightmares, classically a REM phenomenon, are prevalent and underreported, even in individuals with trauma exposure. When specifically queried, trauma-related nightmares (TRN) are frequently associated with disruptive nocturnal behaviors (DNB), consistent with TASD. Capture of DNB in the lab is rare but ambulatory monitoring reveals dynamic autonomic concomitants associated with disturbed dreaming. TRN may be reported in NREM as well as REM sleep, though associated respiratory events may confound this finding. Further, dream content is more distressing in REM. Therapy for this complex disorder likely requires addressing not only the specific TASD components of TRN and DNB but comorbid sleep disorders. TASD is a unique parasomnia developing after trauma. Trauma-exposed individuals should be specifically asked about their sleep and if they have nightmares with or without DNB. Patients who report TRN warrant in-lab PSG as part of their evaluation.

An Ambulatory Polysomnography Study of the Post-traumatic Nightmares of Post-traumatic Stress Disorder

Study Objectives

This study used ambulatory polysomnography (PSG) to investigate post-traumatic nightmares of post-traumatic stress disorder (PTSD). The key research question was whether post-traumatic nightmares occur in both rapid eye movement (REM) and non-REM sleep, and if so, whether nightmares in each sleep stage differed in content, phenomenology, and heart rate response. Underlying sleep disorders were investigated in an exploratory way.

Methods

Thirty-five treatment-seeking veterans, current serving military members, and emergency service personnel undertook full PSG using the Compumedics (Melbourne, Australia) SomtePSG V1 system, during an inpatient psychiatric admission. The PSG recording included an event button to be pressed when a nightmare occurred, allowing us to determine the stage of sleep, changes in heart rate, and associated sleep events. The content and phenomenological features of participants' nightmares were recorded.

Results

Of the 35 participants, 29 reported a nightmare during their sleep study, but only 21 pressed the event button and could recall the content of one or more nightmare. This yielded sleep and nightmare data for 24 nightmares. Of the 24, 10 nightmares arose from REM sleep and 14 from non-REM (stages N1 and N2). Seven were accurate trauma replays and 17 were non-replay or a mixture of replay and non-replay. Most nightmares were associated with respiratory or leg movement events and increase in heart rate on awakening.

Conclusions

Post-traumatic nightmares of PTSD occur in both REM and non-REM sleep and are commonly associated with other sleep disturbances. These findings have important treatment implications.

Relations among Nightmare Frequency and Ego Strength, Death Anxiety, and Sex of College Students

The present study was designed to investigate empirically the relationship between self-reports of nightmare frequency and ego strength and death anxiety in both men and women. In addition, the interrelations among these variables were assessed. 20 undergraduates with high frequencies of nightmares and 20 with low frequencies (10 men and 10 women per group) were administered the Barron Ego Strength Scale and a death anxiety scale. Significant differences were found between nightmare groups on the Barron scale for men and women but none on the death anxiety scale either by nightmare frequency or sex. A significant negative correlation of -.47 between death anxiety and ego strength was found for women and in one high frequency group. Women with high frequencies of nightmares showed the highest correlation, -.83. These data suggest that nightmare frequency may be a mediating factor in the relationship between ego strength, death anxiety, and sex of subject.

Clinical neurophysiology of NREM parasomnias

The nonrapid eye movement (NREM) parasomnias range from age-related developmental phenomena in children to aggressive and injurious motor behaviors in all age groups. These parasomnias are commonly referred to as disorders of arousal and are an important cause of sleep-related injury. Genetic predisposition plays a role in the disorders of arousal, most evident in sleepwalking. Important concepts guiding our current understanding of the pathophysiology of the NREM parasomnias include sleep state instability (a propensity for arousal during NREM sleep), sleep inertia (incomplete awakening from NREM sleep), state dissociation (an ability to simultaneously straddle both NREM sleep and wakefulness), and activation of central pattern generators (permitting expression of subcortically determined motor behaviors without conscious higher cortical input). Management is multifaceted with an emphasis on education and nonpharmacologic measures. The purpose of this chapter is to review wake and NREM neurobiology and update our current understanding of NREM parasomnia pathophysiology, epidemiology, genetics, clinical features, precipitating factors, neurophysiologic evaluation, diagnosis, and clinical management.

Differences in rapid eye movement (REM) sleep abnormalities between posttraumatic stress disorder (PTSD) and major depressive disorder patients: REM interruption correlated with nightmare complaints in PTSD

OBJECTIVE

The presence of repeated nightmares in posttraumatic stress disorder (PTSD) has been hypothesized as a dysfunction of rapid eye movement (REM) sleep, but there has been remarkably little agreement about the pathophysiology. This presents a deterrent to more effective treatments. REM sleep abnormalities including elevated REM density also have been replicated in major depressive disorder (MDD). The purpose of this study was to clarify the difference of REM sleep abnormalities between the two disorders for understanding the pathophysiology of sleep disturbances in PTSD.

METHODS

Polysomnographic measures were compared among 14 PTSD patients (aged 23.7 ± 5.5 years) and 14 MDD patients (aged 27.9 ± 10.1 years) under drug-naive or drug-free conditions. We defined REM interruption by summing the intrusive wake times during the REM period and adding the subsequent wake times to the last epoch of REM period. The significant polysomnographic measures were correlated with PTSD symptoms within the PTSD group.

RESULTS

REM interruption was significantly increased in the PTSD group compared with the MDD group (12.2 vs 2.1 min, p = 0.001). REM density was also significantly increased in the PTSD group compared with the MDD group (30.5 vs 23.1%, p = 0.019). Within the PTSD group, we found significant correlations between the severity of trauma-related nightmare complaints and the percentage of REM interruption (R = 0.62, p = 0.017), but not REM density.

CONCLUSIONS

REM sleep abnormalities are different between PTSD and MDD. Increased REM interruption may be a biological marker correlated with nightmare complaints in PTSD patients. Treatments including pharmacotherapy that reduces REM interruption might ameliorate nightmares in PTSD.

The Stress Acceleration Hypothesis of Nightmares

Adverse childhood experiences can deleteriously affect future physical and mental health, increasing risk for many illnesses, including psychiatric problems, sleep disorders, and, according to the present hypothesis, idiopathic nightmares. Much like post-traumatic nightmares, which are triggered by trauma and lead to recurrent emotional dreaming about the trauma, idiopathic nightmares are hypothesized to originate in early adverse experiences that lead in later life to the expression of early memories and emotions in dream content. Accordingly, the objectives of this paper are to (1) review existing literature on sleep, dreaming and nightmares in relation to early adverse experiences, drawing upon both empirical studies of dreaming and nightmares and books and chapters by recognized nightmare experts and (2) propose a new approach to explaining nightmares that is based upon the Stress Acceleration Hypothesis of mental illness. The latter stipulates that susceptibility to mental illness is increased by adversity occurring during a developmentally sensitive window for emotional maturation—the infantile amnesia period—that ends around age 3½. Early adversity accelerates the neural and behavioral maturation of emotional systems governing the expression, learning, and extinction of fear memories and may afford short-term adaptive value. But it also engenders long-term dysfunctional consequences including an increased risk for nightmares. Two mechanisms are proposed: (1) disruption of infantile amnesia allows normally forgotten early childhood memories to influence later emotions, cognitions and behavior, including the common expression of threats in nightmares; (2) alterations of normal emotion regulation processes of both waking and sleep lead to increased fear sensitivity and less effective fear extinction. These changes influence an affect network previously hypothesized to regulate fear extinction during REM sleep, disruption of which leads to nightmares. This network consists of a fear circuit that includes amygdala, hippocampus, and medial prefrontal cortex and whose substantial overlap with the stress acceleration findings allows the latter to be incorporated into a wider, more developmentally coherent framework.

Trauma associated sleep disorder: A parasomnia induced by trauma

Nightmares and disruptive nocturnal behaviors that develop after traumatic experiences have long been recognized as having different clinical characteristics that overlap with other established parasomnia diagnoses. The inciting experience is typically in the setting of extreme traumatic stress coupled with periods of sleep disruption and/or deprivation. The limited number of laboratory documented cases and symptomatic overlap with rapid eye movement sleep behavior disorder (RBD) and posttraumatic stress disorder (PTSD) have contributed to difficulties in identifying what is a unique parasomnia. Trauma associated sleep disorder (TSD) incorporates the inciting traumatic experience and clinical features of trauma related nightmares and disruptive nocturnal behaviors as a novel parasomnia. The aims of this theoretical review are to 1) summarize the known cases and clinical findings supporting TSD, 2) differentiate TSD from clinical disorders with which it has overlapping features, 3) propose criteria for the diagnosis of TSD, and 4) present a hypothetical neurobiological model for the pathophysiology of TSD. Hyperarousal, as opposed to neurodegenerative changes in RBD, is a component of TSD that likely contributes to overriding atonia during REM sleep and the comorbid diagnosis of insomnia. Lastly, a way forward to further establish TSD as an accepted sleep disorder is proposed.

Nightmares affect the experience of sleep quality but not sleep architecture: an ambulatory polysomnographic study

BACKGROUND

Nightmares and bad dreams are common in people with emotional disturbances. For example, nightmares are a core symptom in posttraumatic stress disorder and about 50% of borderline personality disorder patients suffer from frequent nightmares. Independent of mental disorders, nightmares are often associated with sleep problems such as prolonged sleep latencies, poorer sleep quality, and daytime sleepiness. It has not been well documented whether this is reflected in objectively quantifiable physiological indices of sleep quality.

METHODS

Questionnaires regarding subjective sleep quality and ambulatory polysomnographic recordings of objective sleep parameters were collected during three consecutive nights in 17 individuals with frequent nightmares (NM) and 17 healthy control participants (HC).

RESULTS

NM participants reported worse sleep quality, more waking problems and more severe insomnia compared to HC group. However, sleep measures obtained by ambulatory polysomnographic recordings revealed no group differences in (a) overall sleep architecture, (b) sleep cycle duration as well as REM density and REM duration in each cycle and (c) sleep architecture when only nights with nightmares were analyzed.

CONCLUSIONS

Our findings support the observation that nightmares result in significant impairment which is independent from disturbed sleep architecture. Thus, these specific problems require specific attention and appropriate treatment.

Objective and subjective components of the first-night effect in young nightmare sufferers and healthy participants

The first-night effect--marked differences between the first- and the second-night sleep spent in a laboratory--is a widely known phenomenon that accounts for the common practice of excluding the first-night sleep from any polysomnographic analysis. The extent to which the first-night effect is present in a participant, as well as its duration (1 or more nights), might have diagnostic value and should account for different protocols used for distinct patient groups. This study investigated the first-night effect on nightmare sufferers (NM; N = 12) and healthy controls (N = 15) using both objective (2-night-long polysomnography) and subjective (Groningen Sleep Quality Scale for the 2 nights spent in the laboratory and 1 regular night spent at home) methods. Differences were found in both the objective (sleep efficiency, wakefulness after sleep onset, sleep latency, Stage-1 duration, Stage-2 duration, slow-wave sleep duration, and REM duration) and subjective (self-rating) variables between the 2 nights and the 2 groups, with a more pronounced first-night effect in the case of the NM group. Furthermore, subjective sleep quality was strongly related to polysomnographic variables and did not differ among 1 regular night spent at home and the second night spent in the laboratory. The importance of these results is discussed from a diagnostic point of view.

Bullying and parasomnias: a longitudinal cohort study

BACKGROUND AND OBJECTIVES

Environmental factors such as serious trauma or abuse and related stress can lead to nightmares or night terrors. Being bullied can be very distressing for children, and victims display long-term social, psychological, and health consequences. Unknown is whether being bullied by peers may increase the risk for experiencing parasomnias such as nightmares, night terrors, or sleepwalking.

METHODS

A total of 6796 children of the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort were interviewed at elementary school age (8 and 10 years) about bullying experiences with a previously validated bullying interview and at secondary school age (12.9 years) about parasomnias such as nightmares, night terrors and sleepwalking by trained postgraduate psychologists.

RESULTS

Even after adjusting for pre-existing factors related to bullying and parasomnias, being bullied predicted having nightmares (8 years odds ratio [OR], 1.23; 95% confidence interval [CI], 1.05-1.44; 10 years OR, 1.62; 95% CI, 1.35-1.94) or night terrors (8 years OR, 1.39; 95% CI, 1.10-1.75; 10 years OR, 1.53; 95% CI, 1.18-1.98) at age 12 to 13 years. Especially being a chronic victim was associated with both nightmares (OR, 1.82; 95% CI, 1.46-2.27) and night terrors (OR, 2.01; 95% CI, 1.48-2.74). Being a bully/victim also increased the risk for any parasomnia at ages 8 or 10 years (8 years OR, 1.42; 95% CI, 1.08-1.88; 10 years OR, 1.75; 95% CI, 1.30-2.36). In contrast, bullies had no increased risk for any parasomnias.

CONCLUSIONS

Being bullied increases the risk for having parasomnias. Hence, parents, teachers, school counselors, and clinicians may consider asking about bullying experiences if a child is having parasomnias.

Sleep disorders and depression: brief review of the literature, case report, and nonpharmacologic interventions for depression

Sleep disorders are so frequently associated with depression that, in the absence of sleep complaints, a diagnosis of depression should be made with caution. Insomnia, in particular, may occur in 60%-80% of depressed patients. Depressive symptoms are important risk factors for insomnia, and depression is considered an important comorbid condition in patients with chronic insomnia of any etiology. In addition, some drugs commonly prescribed for the treatment of depression may worsen insomnia and impair full recovery from the illness. The aim of this paper is to review briefly and discuss the following topics: common sleep disturbances during depression (in particular pavor nocturnus, nightmares, hypersomnia, and insomnia); circadian sleep disturbances; and treatment of depression by manipulation of the sleep-wake rhythm (chronotherapy, light therapy, cycles of sleep, and manipulation of the sleep-wake rhythm itself). Finally, we present a case report of a 65-year-old Caucasian woman suffering from insomnia associated with depression who was successfully treated with sleep deprivation.

Nightmares in the bedroom of science: mapping of a neglected sleep disorder

Nightmares are intense and unpleasant dream experiences that characterize approximately 4 percent of the adult population at least on a weekly basis. Nightmare frequency is often co-morbid with other mental complaints; however, recent results indicate that nightmare disorder is independent from waking mental dysfunctions. Nightmare disorder is intimately related to poor subjective sleep quality, and according to polysomnographic studies nightmare subjects’ sleep is characterized by increased sleep fragmentation and hyper-arousal. These findings suggest that instead of the psychopathological perspective nightmare disorder should be viewed as a specific sleep disorder that requires targeted treatment. Nevertheless, in order to choose the adequate treatment procedure clinicians should examine the co-morbid mental disorders as well taking into consideration the severity of nightmare distress, the latter supposed to be the mediator between nightmare frequency and waking mental dysfunctions. Orv. Hetil., 2013, 154, 497–502.

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

STUDY OBJECTIVES

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.

DESIGN

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.

SETTING

Hospital-based sleep research laboratory.

PARTICIPANTS

There were 17 in the nightmare (NMs) group and 23 in the healthy control (CTLs) group.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

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.

CONCLUSIONS

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. SLEEP 2013;36(3):413-419.

Disturbed dreaming and sleep quality: altered sleep architecture in subjects with frequent nightmares

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.

Classification of sleep disorders

The classification of sleep disorders is necessary to discriminate between disorders and to facilitate an understanding of symptoms, etiology, and pathophysiology that allows for appropriate treatment. The earliest classification systems, largely organized according to major symptoms (insomnia, excessive sleepiness, and abnormal events that occur during sleep), were unable to be based on pathophysiology because the cause of most sleep disorders was unknown. These 3 symptom-based categories are easily understood by physicians and are therefore useful for developing a differential diagnosis. The International Classification of Sleep Disorders, version 2, published in 2005 and currently undergoing revision, combines a symptomatic presentation (e.g., insomnia) with 1 organized in part on pathophysiology (e.g., circadian rhythms) and in part on body systems (e.g., breathing disorders). This organization of sleep disorders is necessary because of the varied nature and because the pathophysiology for many of the disorders is still unknown. The International Classification of Sleep Disorders, version 2 provides relevant diagnostic and epidemiological information on sleep disorders to more easily differentiate between the disorders.

Changes in cardiac variability after REM sleep deprivation in recurrent nightmares

STUDY OBJECTIVES

To assess whether dysfunctional autonomic regulation during REM sleep as indexed by heart rate variability (HRV) is a pathophysiological factor in frequent nightmares (NMs).

DESIGN

Monitoring with polysomnography (PSG) and electrocardiography (ECG) for 3 consecutive nights: Night 1 (N1), adaptation night; N2, administration of partial REM sleep deprivation; N3, recovery night. Differences between NM and control (CTL) groups assessed for ECG measures drawn from wakefulness, REM sleep, and Stage 2 sleep on both N1 and N3.

SETTING

Hospital-based sleep laboratory.

PARTICIPANTS

Sixteen subjects with frequent NMs (> or = 1 NM/week; mean age = 26.1 +/- 8.7 years) but no other medical or psychiatric disorders and 11 healthy comparison subjects ( < 1 NM/month; mean age = 27.1+/- 5.6 years).

RESULTS

NM and CTL groups differed on 2 REM sleep measures only on N1; the NM group had longer REM latencies and REM/NREM cycle durations than did the CTL group. No differences were found on time domain and absolute frequency domain ECG measures for either N1 or N3. However, altered HRV for the NM group was suggested by significantly higher LFnu, lower HFnu, and higher LF/HF ratio than for the CTL group.

CONCLUSIONS

Results are consistent with a higher than normal sympathetic drive among NM subjects which is unmasked by high REM sleep propensity. Results also support a growing literature linking anxiety disorders of several types (panic disorder, posttraumatic stress disorder (PTSD), generalized anxiety disorder) to altered HR variability.

REM sleep characteristics of nightmare sufferers before and after REM sleep deprivation

OBJECTIVES

To examine whether disrupted regulation of REM sleep propensity is implicated in nightmare (NM) pathophysiology.

BACKGROUND

Heightened REM propensity induced by REM sleep deprivation is belied by increases in REM %, REM density and the dream-like quality of dream mentation during post-deprivation recovery sleep. Compromised regulation of REM sleep propensity may be a contributing factor in the pathophysiology of frequent NMs.

METHODS

A preliminary study of 14 subjects with frequent NMs (> or = 1 NM/week; 27.6+/-9.9 years) and 11 healthy control subjects (<1 NM/month; 24.3+/-5.3 years) was undertaken. Subjects completed home sleep/dream logs and underwent three nights of polysomnographic recording with REM sleep deprivation on night 2. Group differences were assessed for a battery of REM sleep and dream measures on nights 1 and 3.

RESULTS

Several measures, including #skipped early-night REM periods, REM latency, REM/NREM cycle length, early/late REM density, REM rebound, late-night REM% and dream vividness, suggested that REM sleep propensity was abnormally low for the frequent NM group throughout the 3-day study.

CONCLUSIONS

Findings raise the possibility that REM anomalies recorded from NM sufferers sleeping in the laboratory environment reflect a disruption of one or more endogenous regulators of REM sleep propensity.

Correlates and Treatments of Nightmares in Adults

Nightmares, distressing dreams that primarily arise from REM sleep, are prevalent among the general population and even more so among clinical populations. The frequency of nightmares and related nightmare distress are linked to both sleep disturbance and waking psychopathology. Based on the extant evidence, nightmares appear to be particularly relevant to posttraumatic stress disorder, and may even be implicated in its pathophysiology. Significant advances in treatment have occurred in recent years, with effective pharmacological and psychosocial interventions now available. Despite the progress that has been made, however, more consistent assessment methods and more rigorous study designs are needed to fully understand the causes and consequences of nightmares.

The relationship between disturbed dreaming and somatic distress: a prospective investigation

Despite an abundant literature on disturbed dreaming (DD) incidence and psychopathology, little is known about the pathogenesis of these dream disturbances. Recent work strongly suggests that DD distress may be the primary determinant of the relationship between DD and waking psychological impairment. This is the first empirical investigation of the possible role of somatic distress as a crucial pathway in this relationship. A total of 313 college undergraduates completed 3 measures of somatic distress (SCL-90-R Somatization scale, Somatic Interpretations Questionnaire and the Anxiety Sensitivity Index) and then monitored their DD incidence and distress for 21 consecutive days. It was predicted that high levels of somatic distress would be associated with heightened levels of both DD incidence and distress. Although the results were somewhat mixed, individuals who reported more incidents of both bad dreams and nightmares did indeed report higher levels of somatic distress. The results were largely consistent with our predictions and the findings are discussed with regard to recent modeling by in identifying key cognitive diatheses for the development of DD.

Sleep findings in young adult patients with posttraumatic stress disorder

BACKGROUND

Laboratory sleep studies in posttraumatic stress disorder (PTSD) have not provided consistent evidence of sleep disturbance, despite apparent sleep complaints. Most of these studies have investigated middle-aged chronic PTSD subjects with a high prevalence of comorbidities such as substance dependence and/or personality disorder.

METHODS

Ten young adult PTSD patients (aged 23.4 +/- 6.1 years) without comorbidities of substance dependence and/or personality disorder underwent 2-night polysomnographic recordings. These sleep measures were compared with those of normal control subjects and were correlated with PTSD symptoms.

RESULTS

Posttraumatic stress disorder patients demonstrated significantly poorer sleep, reduced sleep efficiency caused by increased wake time after sleep onset, and increased awakening from rapid eye movement (REM) sleep (REM interruption). We found significant positive correlations between the severity of trauma-related nightmare complaints and the percentage of REM interruption, as well as wake time after sleep onset.

CONCLUSIONS

The results indicate that trauma-related nightmares are an important factor resulting in increased REM interruptions and wake time after sleep onset in PTSD.

Nightmares: A new neurocognitive model

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.