The Stress Acceleration Hypothesis of Nightmares

From single to multiple: the association of childhood trauma with frequent nightmares among youth

OBJECTIVE

Childhood trauma is a known risk factor for frequent nightmares in youth, but the effects of single and multiple traumas remain unclear. This cross-sectional study aimed to investigate the association between single and multiple childhood traumas and frequent nightmares.

METHODS

Youth aged 12-25 years completed online questionnaires on childhood trauma and nightmares. Cumulative scores and latent class analyses were used to identify multiple childhood traumas. Logistic regression was used to investigate the association between childhood trauma types and frequent nightmares.

RESULTS

Of the 6145 participants, 27.2 % (n = 1670) reported frequent nightmares during the past year. Adjusted analyses showed emotional abuse (OR: 1.45, 95 %CI: 1.23-1.87) and emotional neglect (OR: 1.19, 95 %CI: 1.03-1.37) significantly increased the risk of nightmares. The risk of frequent nightmares increased with the number of traumas: 26 % for one, 36 % for two, and 51 % for three or more, compared with none. The latent class analysis identified three multiple trauma patterns: "low abuse, low neglect" (n = 3837), "low abuse, high neglect" (n = 2089), and "high abuse, high neglect" (n = 219), with increased nightmares risks of 26 % and 47 % in the latter two, respectively, versus the first. However, no significant difference was observed between "low abuse, high neglect" and "high abuse, high neglect" (OR: 1.17, 95 % CI: 0.85-1.60).

CONCLUSIONS

Our findings enhance the understanding of the heterogeneity of childhood trauma and its association with nightmares. Prevention and treatment programs for nightmares should be tailored according to different patterns of childhood trauma.

Distressing dreams in trauma survivors: using a sleep diary mobile app to reveal distressing dream characteristics and their relationship to symptoms and suicidal ideation in trauma-exposed adults

Study Objectives

Trauma nightmares are a core feature of PTSD, with potentially devastating implications for mental health outcomes. Treatments remain unsatisfactory and nightmares are poorly understood, both biologically and phenomenologically; measurement methods are limited. The aims of the current analyses were to (1) characterize distressing dreams in trauma survivors, (2) examine the relationships of dream features to next-day symptoms and to suicidal ideation, and (3) validate sleep diary mobile app items for the measurement of clinically relevant dream characteristics.

Methods

Adult male and female veterans and nonveterans with a history of PTSD criterion trauma and at least 1 nightmare weekly were enrolled. Participants completed 3 weeks of sleep diary, including bedtime and morning surveys and weekly assessments. They also completed a Clinician-Administered PTSD Scale (CAPS)-5 PTSD assessment. Multivariable mixed models with repeated measures and standard regression were utilized to examine relationships between dream features and next-day symptoms and suicidal ideation.

Results

Dream features and dream distress independently predict clinically relevant outcomes; no single feature was sufficient for predicting all outcomes of interest. In particular, the replicative quality of trauma nightmares stood out in terms of associations with next-day symptoms, CAPS severity, and suicidal ideation. Subjective dream duration, extent of postdream arousal, and subjective distress severity also independently predicted daytime symptoms.

Conclusions

Results underscore the importance of examining dream characteristics to understand nightmare effects and associations with suicidal ideation. These findings also underscore the utility of mobile app technology for obtaining informative data with high temporal resolution in an appealing and user-friendly manner.

Nightmare experiences and perceived ethnic discrimination amongst female university students in the United Arab Emirates: a cross-sectional study

Perceived ethnic discrimination is known to be associated with anxiety and depression, and in turn, anxiety and depression are known to be associated with nightmare frequency and distress. This elicits a question: is perceived ethnic discrimination associated with nightmare frequency and distress? In this study, 179 female university students from the United Arab Emirates were assessed to answer that question. Results showed that while anxiety and depression were related to nightmare experiences, perceived ethnic discrimination was a stronger predictor of nightmare experiences. We posit two explanations for this finding: one based on psychoanalytical insights, and the other based on the Disposition-Stress model with neurobiological correlates. No significant differences were found across ethnicity when it comes to nightmare experiences or perceived ethnic discrimination. This is an encouraging sign of optimal societal integration in the United Arab Emirates.

The relationships between insomnia, nightmares, and dreams: A systematic review

Insomnia and nightmares are both prevalent and debilitating sleep difficulties. The present systematic review aims to document the relationships between insomnia and nightmares in individuals without a concomitant psychopathology. The relationships between insomnia and dreams are also addressed. PsycINFO and Medline were searched for papers published in English or French from 1970 to March 2023. Sixty-seven articles were included for review. Most results support positive relationships between insomnia variables and nightmare variables in individuals with insomnia, individuals with nightmares, the general population, students, children and older adults, and military personnel and veterans. These positive relationships were also apparent in the context of the COVID-19 pandemic. Some psychological interventions, such as Imagery Rehearsal Therapy, might be effective in alleviating both nightmares and insomnia symptoms. Regarding the relationships between insomnia and dreams, compared with controls, the dreams of individuals with insomnia are characterized by more negative contents and affects. The results show that insomnia and nightmares are connected and may be mutually aggravating. A model is proposed to explain how insomnia might increase the likelihood of experiencing nightmares, and how nightmares can in turn lead to sleep loss and nonrestorative sleep.

Altered parasympathetic activity during sleep and emotionally arousing wakefulness in frequent nightmare recallers

Nightmare disorder is characterized by dysfunctional emotion regulation and poor subjective sleep quality reflected in pathophysiological features such as abnormal arousal processes and sympathetic influences. Dysfunctional parasympathetic regulation, especially before and during rapid eye movement (REM) phases, is assumed to alter heart rate (HR) and its variability (HRV) of frequent nightmare recallers (NM). We hypothesized that cardiac variability is attenuated in NMs as opposed to healthy controls (CTL) during sleep, pre-sleep wakefulness and under an emotion-evoking picture-rating task. Based on the polysomnographic recordings of 24 NM and 30 CTL participants, we examined HRV during pre-REM, REM, post-REM and slow wave sleep, separately. Additionally, electrocardiographic recordings of resting state before sleep onset and under an emotionally challenging picture-rating task were also analyzed. Applying repeated measures analysis of variance (rmANOVA), a significant difference was found in the HR of NMs and CTLs during nocturnal segments but not during resting wakefulness, suggesting autonomic dysregulation, specifically during sleep in NMs. As opposed to the HR, the HRV values were not significantly different in the rmANOVA in the two groups, implying that the extent of parasympathetic dysregulation on a trait level might depend on the severeness of dysphoric dreaming. Nonetheless, in the group comparisons, the NM group showed increased HR and reduced HRV during the emotion-evoking picture-rating task, which aimed to model the nightmare experience in the daytime, indicating disrupted emotion regulation in NMs under acute distress. In conclusion, trait-like autonomic changes during sleep and state-like autonomic responses to emotion-evoking pictures indicate parasympathetic dysregulation in NMs.

Alexithymia is associated with insomnia in Chinese patients with schizophrenia

Background

Sleep disorders are prevalent among patients with schizophrenia and are associated with several negative consequences. Although, researchers have recently suggested that sleep disorders have a close correlation with alexithymia, and schizophrenia also has a strong correlation with alexithymia, there have been few studies on the relationships between schizophrenia, sleep disorders and alexithymia. Therefore, this study aimed to explore the relationships between psychiatric symptoms, alexithymia and sleep problems in patients with schizophrenia so as to provide a reference for the clinical treatment of this comorbidity.

Methods

In total, 977 patients with schizophrenia were recruited for this study. The Insomnia Severity Index (ISI) was used to assess sleep disorders, and the Positive and Negative Syndrome Scale (PANSS), Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Toronto Alexithymia Scale (TAS) were used to evaluate clinical symptoms, cognitive functions and the ability to express emotion, respectively.

Results

The results indicated that the PANSS subscales (G-subscore) and TAS group were risk factors for insomnia in schizophrenia patients (all p < 0.05). The mediation model showed the standardized path coefficients from schizophrenia to alexithymia (β = 0.104, p < 0.001) and from alexithymia to insomnia (β = 0.038, p < 0.001) were statistically significant.

Conclusion

The results of this study indicated that alexithymia is associated with sleep disturbance in patients with schizophrenia. These findings may provide a new avenue for the treatment of schizophrenia patients with sleep disorders.

Effects of Bullying on Anxiety, Depression, and Posttraumatic Stress Disorder Among Sexual Minority Youths: Network Analysis

BACKGROUND

Bullying victimization is highly prevalent among sexual minority youths, particularly in educational settings, negatively affecting their mental health. However, previous studies have scarcely explored the symptomatic relationships among anxiety, depression, and posttraumatic stress disorder (PTSD) among sexual minority youths who experienced bullying on college campuses.

OBJECTIVE

The objectives of our study were to (1) characterize the anxiety-depression-PTSD network structures of gay or lesbian, bisexuals, and other sexual minority youths previously bullied on college campuses; and (2) compare symptomatic associations in the anxiety-depression-PTSD networks among bullied sexual minority youths and heterosexual youths' groups.

METHODS

This cross-sectional study recruited college participants from Jilin Province, China. Data were analyzed using a subset of the data extracted after screening for sexual orientation and history of bullying victimization. Sexual minority youths were then divided into 3 subgroups: gay or lesbian (homosexual), bisexual, and other. Mental health symptom severity was assessed using scales: the 7-item Generalized Anxiety Disorder Scale measuring anxiety, the 9-item Patient Health Questionnaire measuring depression, and the 10-item Trauma Screening Questionnaire measuring PTSD symptoms. Combining the undirected and Bayesian network analyses, the anxiety-depression-PTSD networks were compared among sexual minority youths subgroups, and the difference between heterosexual youths and sexual minority youths was investigated. Chi-square tests were used to compare the difference in categorical variables, while independent-sample t tests were run on continuous variables.

RESULTS

In this large-scale sample of 89,342 participants, 12,249 identified as sexual minority youths, of which 1603 (13.1%, 95% CI 12.5%-13.7%) reported being bullied on college campuses in the past year. According to the expected influence (EI) and bridge expected influence (bEI) index, in the global network structure of anxiety, depression, and PTSD, sad mood (EI=1.078, bEI=0.635) and irritability (EI=1.077, bEI=0.954) were identified as central and bridge symptoms; emotional cue reactivity (EI=1.015) was a central symptom of PTSD in this global network. In the anxiety-depression-PTSD Bayesian network, anhedonia had the highest prediction priority for activating other symptoms; and feeling afraid linked symptoms from anxiety to the PTSD community. Compared to their heterosexual counterparts, sexual minority youths exhibited a stronger association between difficulty concentrating and appetite. The "sad mood-appetite" edge was strongest in the gay or lesbian network; the "irritability-exaggerated startle response" edge was strongest in the bisexual network.

CONCLUSIONS

For the first time, this study identified the most central and bridge symptoms (sad mood and irritability) within the depression-anxiety-PTSD network of sexual minority youths with past bullying-victim experiences on college campuses. Emotional cue reactivity, anhedonia, and feeling afraid were other vital symptoms in the comorbid network. Symptomatic relationships existed showing heterogeneity in bullied heterosexual youths and sexual minority youth networks, which also was present within the sexual minority youth subgroups. Consequently, refined targeted interventions are required to relieve anxiety, depression, and PTSD symptoms.

Vivid dreams are associated with a high percentage of REM sleep: a prospective study in veterans

STUDY OBJECTIVES

Vivid dreams are dreams that feel real or are associated with dream enactment behavior. They are prevalent in veterans, especially in those with psychiatric disorders such as post-traumatic stress disorders. Such psychiatric disorders have known association with abnormalities in rapid eye movement (REM) sleep. Vivid dreams are also described in neurological conditions, such Lewy body dementias, which are also associated with REM sleep abnormality. Although vivid dreams occur in neuropsychiatric disorders that have REM sleep abnormalities, there are no studies that have directly investigated an association between vivid dreams and REM sleep. We sought to study vivid dreams and REM sleep in veterans.

METHODS

Veterans undergoing polysomnography at our hospital were invited to enroll. Participants completed a dream-related questionnaire the morning after their polysomnography.

RESULTS

We prospectively enrolled 505 veterans. After a night in the sleep laboratory, 196 of 504 (39%) reported experiencing a dream, and, of those, 117 of 190 (62%) described their dream as vivid. Discrepancies in patient totals are secondary to missing questionnaire data. Our novel finding is that participants with a high percentage of REM sleep (above 25%) were more than twice likely to report a vivid dream than participants with a lower percentage of REM sleep (P < .0001). Nonvivid dreams were not associated with a high percentage of REM sleep.

CONCLUSIONS

Vivid dreams are associated with a high percentage of REM sleep. Further research into the role of REM sleep abnormalities in vivid dreams may help to advance understanding of neuropsychiatric disorders.

CITATION

Fattal D, Platti N, Hester S, Wendt L. Vivid dreams are associated with a high percentage of REM sleep: a prospective study in veterans. J Clin Sleep Med. 2023;19(9):1661-1668.

Associations between frequent nightmares, nightmare distress and depressive symptoms in adolescent psychiatric patients

BACKGROUND

Nightmares are common in patients with psychiatric disorders. Patients with psychiatric disorders often experience depressive symptoms. Nightmares have been associated with depressive symptoms among adolescents. Previous studies have explored the mediating role of nightmare distress in the relationship between frequent nightmares and depressive symptoms in the general adolescent population. We aimed to explore the associations between frequent nightmares, nightmare distress, and depressive symptoms in Chinese adolescent patients with psychiatric disorders.

METHODS

A total of 408 adolescents participated in this study. A self-administered questionnaire was used to measure nightmare frequency, nightmare distress, depressive symptoms, and covariates. Linear regressions and mediation analyses were performed to examine the associations between nightmare frequency, nightmare distress, and depressive symptoms.

RESULTS

The mean age of participants was 15.31 ± 1.88 years, and 152 (37.3%) were boys. The prevalence of frequent nightmares in adolescent patients with psychosis was 49.3%. Girls reported more frequent nightmares and had significantly higher scores of depressive symptoms and nightmare distress. Patients with frequent nightmares had higher scores of nightmare distress and depressive symptoms. Frequent nightmares and nightmare distress were significantly associated with depressive symptoms. Nightmare distress had a full mediating effect on the correlation between frequent nightmares and depressive symptoms.

CONCLUSIONS

In Chinese adolescent patients with psychiatric disorders, frequent nightmares and nightmare distress were associated with depressive symptoms, whereas the association between frequent nightmares and depressive symptoms was mediated by nightmare distress. Interventions for nightmare distress may be more useful in reducing depressive symptoms in adolescent patients with psychiatric disorders.

Autonomic activity, posttraumatic and nontraumatic nightmares, and PTSD after trauma exposure

BACKGROUND

Nightmares are a hallmark symptom of posttraumatic stress disorder (PTSD). This strong association may reflect a shared pathophysiology in the form of altered autonomic activity and increased reactivity. Using an acoustic startle paradigm, we investigated the interrelationships of psychophysiological measures during wakefulness and PTSD diagnosis, posttraumatic nightmares, and nontraumatic nightmares.

METHODS

A community sample of 122 trauma survivors were presented with a series of brief loud tones, while heart rate (HRR), skin conductance (SCR), and orbicularis oculi electromyogram (EMGR) responses were measured. Prior to the tone presentations, resting heart rate variability (HRV) was assessed. Nightmares were measured using nightmare logs. Three dichotomous groupings of participants were compared: (1) current PTSD diagnosis (n = 59), no PTSD diagnosis (n = 63), (2) those with (n = 26) or without (n = 96) frequent posttraumatic nightmares, and (3) those with (n = 22) or without (n = 100) frequent nontraumatic nightmares.

RESULTS

PTSD diagnosis was associated with posttraumatic but not with nontraumatic nightmares. Both PTSD and posttraumatic nightmares were associated with a larger mean HRR to loud tones, whereas nontraumatic nightmare frequency was associated with a larger SCR. EMGR and resting HRV were not associated with PTSD diagnosis or nightmares.

CONCLUSIONS

Our findings suggest a shared pathophysiology between PTSD and posttraumatic nightmares in the form of increased HR reactivity to startling tones, which might reflect reduced parasympathetic tone. This shared pathophysiology could explain why PTSD is more strongly related to posttraumatic than nontraumatic nightmares, which could have important clinical implications.

Has the COVID-19 Pandemic Traumatized Us Collectively? The Impact of the COVID-19 Pandemic on Mental Health and Sleep Factors via Traumatization: A Multinational Survey

PURPOSE

The COVID-19 pandemic affects mental health and sleep, resulting in frequent nightmares. Therefore, identifying factors associated with nightmare frequency is important, as it can indicate mental health issues. The study aimed to investigate increases in nightmare frequency comparing the pre-pandemic and pandemic period, and identify its risk factors. Further, the mediating role of post-traumatic stress disorder symptoms between the pandemic and nightmares is explored.

PATIENTS AND METHODS

For this cross-sectional survey data were obtained via self-rating online survey (ICOSS: details in Partinen et al, 2021), which was open to anyone older than 18 years. The final volunteer sample consisted of 15,292 participants, divided according to their nightmare frequency (high: ≥1-2 nights/week; low: <1-2 nights/week). A total of 9100 participants were excluded if answers on variables of interest were missing or receiving rewards for participation. Chi-square tests identified changes of nightmare frequency. Predictors of high nightmare frequency were assessed using logistic regression and presented as Odds Ratios. Post-hoc mediation models were used to investigate the role of post-traumatic stress symptoms (PTSS).

RESULTS

The mean age was 41.63 (SD=16.55) with 64.05% females. High nightmare frequency increased significantly from 13.24% to 22.35% during the pandemic. Factors associated with it included self-reported PTSS (OR=2.11), other mental disorders and various sleep disorders or problems. Financial burden due to the pandemic, confinement, having had COVID-19, and work situation during the pandemic were associated with nightmare frequency, those relations were partly mediated through PTSS.

CONCLUSION

Our results display the pandemic influence on nightmare frequency, which in turn connects to multiple mental health and sleep factors. These relations were partly mediated through PTSS. The COVID-19 pandemic appears to have caused traumatization of a substantial proportion of society. Health care workers should consider nightmares in their screening routines, as it might indicate PTSS and/or other mental and sleep disorders.

Pharmacological Management of Nightmares Associated with Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) can be a chronic and disabling condition. Post-traumatic nightmares (PTNs) form a core component of PTSD and are highly prevalent in this patient population. Nightmares in PTSD have been associated with significant distress, functional impairment, poor health outcomes, and decreased quality of life. Nightmares in PTSD are also an independent risk factor for suicide. Nightmare cessation can lead to improved quality of life, fewer hospital admissions, lower healthcare costs, and reduced all-cause mortality. Effective treatment of nightmares is critical and often leads to improvement of other PTSD symptomatology. However, approved pharmacological agents for the treatment of PTSD have modest effects on sleep and nightmares, and may cause adverse effects. No pharmacological agent has been approved specifically for the treatment of PTNs, but multiple agents have been studied. This current narrative review aimed to critically appraise proven as well as novel pharmacological agents used in the treatment of PTNs. Evidence of varying quality exists for the use of prazosin, doxazosin, clonidine, tricyclic antidepressants, trazodone, mirtazapine, atypical antipsychotics (especially risperidone, olanzapine and quetiapine), gabapentin, topiramate, and cyproheptadine. Evidence does not support the use of venlafaxine, β-blockers, benzodiazepines, or sedative hypnotics. Novel agents such as ramelteon, cannabinoids, ketamine, psychedelic agents, and trihexyphenidyl have shown promising results. Large randomized controlled trials (RCTs) are needed to evaluate the use of these novel agents. Future research directions are identified to optimize the treatment of nightmares in patients with PTSD.

Case Study of Cognitive Behavioral Therapy for Nightmares in Children With and Without Trauma History

These case examples depict the adaptation of Exposure, Relaxation, and Rescripting Therapy (ERRT) for use with children. ERRT was developed for trauma-related nightmares in adults. The current study modified ERRT to be developmentally appropriate for children, incorporating child appropriate language, interactive activities, and parent coaching. The modified treatment, called cognitive-behavioral therapy for nightmares in children (CBT-NC), added additional stress-management components to further adapt the treatment for children with anxiety-related nightmares and no trauma history. These case studies describe the course of treatment for two girls whose nightmares had different etiologies—one experiencing trauma-related nightmares and the other experiencing idiopathic anxiety-related nightmares. This was the first application of CBT-NC for idiopathic nightmares. Both children responded positively to treatment, and treatment gains were maintained at 3- and 6-month follow-up. Improvements were seen not only for nightmare frequency and distress, but overall sleep also improved. Findings demonstrate that this adapted nightmare treatment for children is feasible and promising for nightmares in children, regardless of nightmare etiology.

The Oneiric Activity during and after the COVID-19 Total Lockdown in Italy: A Longitudinal Study

A growing body of evidence highlights that the COVID-19 pandemic affected oneiric activity. However, only a few studies have assessed the longitudinal changes in dream phenomenology during different phases of the pandemic, often focused on a limited number of dream variables. The aim of the present study was to provide an exhaustive assessment of dream features during total lockdown (TL) and a post-lockdown (PL) period characterized by eased restrictive measures in Italy. We performed a longitudinal study using a web-based survey to collect demographic, COVID-19 related, clinical, sleep, and dream data at TL and PL. Our final sample included 108 participants. The high frequency of poor sleep quality, anxiety, and depressive symptoms observed during TL remained stable at PL, while sleep latency (t = −4.09; p < 0.001) and PTSD-related disruptive nocturnal behaviors (t = −5.68; p < 0.001) exhibited a reduction at PL. A PL decrease in time spent with digital media was observed (t = −2.77; p = 0.007). We found a strong PL reduction in dream frequency (t = −5.49; p < 0.001), emotional load (t = −2.71; p = 0.008), vividness (t = −4.90; p < 0.001), bizarreness (t = −4.05; p < 0.001), length (t = −4.67; p < 0.001), and lucid dream frequency (t = −2.40; p = 0.018). Fear was the most frequently reported emotion in dreams at TL (26.9%) and PL (22.2%). Only the frequency of specific lockdown-related dream contents exhibited a reduction at PL. These findings highlight that the end of the home confinement had a strong impact on the oneiric activity, in the direction of reduced dream frequency, intensity, and lockdown-related contents. The co-occurrence of such changes with a decline in nocturnal PTSD-related symptoms, sleep latency, and time with digital media suggests an influence of post-traumatic stress levels, lifestyle modifications, and sleep pattern on dream changes during different phases of the pandemic. The stable prevalence of fear in dreams and the large frequency of poor sleep quality, depressive symptoms, and anxiety are probably related to the persistence of many negative consequences of the pandemic. Overall, these results are consistent with the continuity hypothesis of dreams.

Sleep Complaints Among School Children

Sleep complaints are common among children. These include both night-time and daytime symptoms, such as trouble falling asleep, problems in maintaining sleep, snoring, and unusual events during sleep and daytime functioning impairment. However, sleep complaints in children are often overlooked and undertreated in clinical practice. Untreated sleep problems may further impact on children's development and will persist into adulthood in some cases. This review summarizes the common sleep complaints and disorders in school children, and provides an overview of the epidemiology, clinical features, consequences, and treatment of the sleep problems.

Dissociated Effects of Age and Recent Troubling Experiences on Nightmares, Threats and Negative Emotions in Dreams

Several studies have highlighted associations between adverse life events and the dysphoric character of dream experiences. This degree of continuity between waking-life and dream content seems partly attributed to the emotional and personal attachment linked to the incorporated waking experiences. Numerous changes in the processing of emotion-related stimuli are also reported across different human developmental stages. Therefore, we were interested in testing whether age would modulate the impact of recent troubling experiences on dream characteristics. Two hundred sixty participants, evenly distributed in five developmental stages, matched for gender and their exposure to a troubling experience, were selected from a large sample collected for a previous normative study of dreams of Canadians. Participants completed a dream questionnaire from which independent judges subsequently scored the dreams. We observed no interactions between the experience of troubling events and age. However, individuals who experienced a recent troubling event reported a higher frequency of nightmares and their dreams were more emotionally negative. Participants who experienced a moderately severe troubling event were also more likely to experience a dream whose maximal threat severity was of moderate intensity. Adolescents and young adults had dreams with a higher level of oneiric threats compared to older adults (>40 years old). Young adults also reported a higher frequency of nightmares compared to older adults. Our findings have implications for modern dream theories. They also suggest that dysphoric dreams might serve as potential proxies of mental health status and developmental stages. Future studies are now needed to explore the implications of these findings for psychological adaptation.

Can You Sleep? - Effect of Retrospective Recall of Child Maltreatment on Sleep Parameters and the Mediating Role of Psychological Distress Among Students of Two German Universities

PURPOSE

Child maltreatment may be linked with long-term sleeping disorders and limited coping with stress. Yet, the potential relationships are only marginally studied.

PATIENTS AND METHODS

Based on a sample of young adults (n = 312) this study aims at exploring the effects of child maltreatment and the experience of threat to personal safety and life in childhood on sleep disturbances in early adulthood. Data were collected at the two study sites, Ulm University and Bielefeld University, by an online survey. For both risk factors, child maltreatment and the experience of threat to personal safety and life in childhood, a direct impact on sleep disturbances and an indirect path via psychological distress were tested using Structural Equation Modelling (SEM).

RESULTS

In these models, the direct path to sleep disturbances turned out to be significant for the experience of threat to personal safety and life (Path C: b = 0.18, p = 0.013), but not for child maltreatment (Path C: b = 0.05, p = 0.491). However, the current level of psychological distress was found to have a mediating effect on sleep disturbances for both risk factors, thereby confirming indirect significant effects.

CONCLUSION

Considering that the etiological pathway of child maltreatment on sleeping disturbances is mediated via psychological distress, this provides a venue to test in future research whether stress reduction interventions can reduce the negative consequences of child maltreatment on sleep disorders.

A clinical approach to nightmares and bad dreams in cognitive–behavioural therapy

Clinicians trained in cognitive–behavioural therapy (CBT) are frequently not trained to work with dreams. Given the high prevalence and impact of nightmares and bad dreams, empowering CBT therapists to effectively work with these sleep phenomena is crucial to improve therapeutic outcomes. This article briefly outlines a cognitive–behavioural model of dreams and reviews some clinical guidelines for directly and indirectly addressing nightmares and bad dreams in CBT practice.

What goes around comes around: Nightmares and daily stress are bidirectionally associated in nurses

Nurses may experience frequent nightmares due to stressful work environments. Nightmares may also exacerbate stress among nurses, although this has yet to be tested empirically. We examined daily bidirectional associations between stress severity and nightmares, and moderation by post-traumatic stress disorder (PTSD) symptoms. 392 nurses (92% female; 78% White) completed 14 days of sleep diaries to assess previous-day stress severity and nightmare occurrence and severity. PTSD symptoms were assessed at baseline. Multilevel models were used to examine bidirectional, within-person associations between daily stress and nightmares, and cross-level moderation by baseline PTSD symptoms. 47.2% of nurses reported at least one nightmare across the two weeks. Days with greater stress were associated with higher odds of experiencing a nightmare (OR = 1.22, p = 0.001), as well as greater nightmare severity (b = 0.09, p = 0.033). Nightmare occurrence was associated with greater next-day stress severity (b = 0.15, p < 0.001). Daily stress and nightmare associations were similar for those with and without PTSD symptoms. Nightmares and stress may occur in a bidirectional fashion. Nurses face intense occupational demands and frequent exposure to potentially traumatic events. Studies should explore whether targeting nightmares and stress may improve nurses' health and well-being.

Gender Differences in Childhood Maltreatment: A Comparative Study of Nightmare Sufferers and Non-sufferers

Child maltreatment has been identified as a significant problem, both within India and outside. According to UNICEF, over the last decade, there has been a growing recognition about this, but the problem has remained unresolved largely due to being underreported and undocumented. Previous research in this area has reported inconsistent gender differences across the world. Besides, there are shreds of evidence to suggest that childhood maltreatment would be associated with nightmares later in life, but a handful of studies exist in this context. Moreover, there is a paucity of research concerning the interaction effect of gender and group (nightmare sufferer vs non-sufferer) on childhood maltreatment. Owing to the insufficient research and inconsistent findings, the present study aimed to investigate gender differences in childhood maltreatment among nightmare sufferers as compared to non-sufferers. A total of 120 participants were selected from New Delhi. The results of two-way ANOVA suggest that the nightmares later in life would be associated with the abuse and neglect experienced during childhood as nightmare sufferer group reported having higher rates of child abuse and neglect than non-sufferers. It also suggests that male participants in general experience childhood maltreatment more than females; however, emotional abuse was experienced by males only if they belonged to the nightmare sufferer group.

Stuck in a lockdown: Dreams, bad dreams, nightmares, and their relationship to stress, depression and anxiety during the COVID-19 pandemic

BACKGROUND

An upsurge in dream and nightmare frequency has been noted since the beginning of the COVID-19 pandemic and research shows increases in levels of stress, depression and anxiety during this time. Growing evidence suggests that dream content has a bi-directional relationship with psychopathology, and that dreams react to new, personally significant and emotional experiences. The first lockdown experience was an acute event, characterized by a combination of several unprecedent factors (new pandemic, threat of disease, global uncertainty, the experience of social isolation and exposure to stressful information) that resulted in a large-scale disruption of life routines. This study aimed at investigating changes in dream, bad dream and nightmare recall; most prevalent dream themes; and the relationship between dreams, bad dreams, nightmares and symptoms of stress, depression and anxiety during the first COVID-19 lockdown (April-May 2020) through a national online survey.

METHODS

968 participants completed an online survey. Dream themes were measured using the Typical Dreams Questionnaire; stress levels were measured by the Cohen's Perceived Stress Scale; symptoms of anxiety were assessed by Generalized Anxiety Disorder (GAD-7) scale; and symptoms of depression were assessed using the Quick Inventory of Depressive Symptomatology.

RESULTS

34% (328) of participants reported increased dream recall during the lockdown. The most common dream themes were centered around the topics of 1) inefficacy (e.g., trying again and again, arriving late), 2) human threat (e.g., being chased, attacked); 3) death; and 4) pandemic imagery (e.g., being separated from loved ones, being sick). Dream, bad dream and nightmare frequency was highest in individuals with moderate to severe stress levels. Frequency of bad dreams, nightmares, and dreams about the pandemic, inefficacy, and death were associated with higher levels of stress, as well as with greater symptoms of depression and anxiety.

CONCLUSIONS

Results support theories of dream formation, environmental susceptibility and stress reactivity. Dream content during the lockdown broadly reflected existential concerns and was associated with increased symptoms of mental health indices.

Dream Recall/Affect and the Hypothalamic-Pituitary-Adrenal Axis

In this concise review, we present an overview of research on dream recall/affect and of the hypothalamic–pituitary–adrenal (HPA) axis, discussing caveats regarding the action of hormones of the HPA axis (mainly cortisol and its free form, cortisol-binding globulin and glucocorticoid receptors). We present results of studies regarding dream recall/affect and the HPA axis under physiological (such as waking) or pathological conditions (such as in Cushing’s syndrome or stressful situations). Finally, we try to integrate the effect of the current COVID-19 situation with dream recall/affect vis-à-vis the HPA axis.

Frequent nightmares and its associations with psychological and sleep disturbances in hospitalized patients with cardiovascular diseases

AIMS

Frequent nightmares can pose a serious clinical problem, especially in association with sleep and psychological disturbances, in the general population. However, this association has not been investigated in inpatients with cardiovascular (CV) diseases. Furthermore, whether CV medications could induce iatrogenic nightmares remains unknown. In a cross-sectional designed study, we evaluated the prevalence and determinants of frequent nightmares and its association with sleep and psychological disturbances among hospitalized CV patients.

METHODS AND RESULTS

A total of 1233 patients (mean age, 64 ± 15 years; 25.1% female) hospitalized for various CV diseases in a single university hospital were enrolled. We assessed nightmares and sleep characteristics using the Pittsburgh Sleep Quality Index (PSQI), sleep-disordered breathing (SDB) using nocturnal pulse oximetry, and psychological disturbances using Hospital Anxiety and Depression Scale (HADS). Overall, 14.8% and 3.6% of the patients had at least one nightmare per month and per week (frequent nightmares), respectively. In this cohort, 45.9% had insomnia (modified PSQI > 5), 28.0% had SDB (3% oxygen desaturation index > 15), 18.5% had depression (HADS-depression ≥ 8), and 16.9% had anxiety (HADS-anxiety ≥ 8). Frequent nightmares were not associated with CV medications and SDB but were associated with depression [odds ratio (OR) = 4.61, 95% confidence interval (CI) = 2.03-10.48], anxiety (OR = 5.32, 95% CI = 2.36-12.01), and insomnia (OR = 7.15, 95% CI = 2.41-21.22).

CONCLUSIONS

Frequent nightmares were not uncommon in patients hospitalized for CV diseases. Although the cause-effect relationship is unclear, frequent nightmares were associated with psychological disturbances and insomnia, but not iatrogenic factors, among hospitalized CV patients. Cardiologists should be more conscientious to nightmare complaints with respect to screening for psychological disturbances and insomnia.

Centrally acting anticholinergic drug trihexyphenidyl is highly effective in reducing nightmares associated with post-traumatic stress disorder

INTRODUCTION

Following a case study on scopolamine butyl bromide, an anticholinergic drug, we studied the effect of a central anticholinergic drug on post-traumatic stress disorder (PTSD)-related flashbacks and nightmares.

METHODS

We administered trihexyphenidyl (TP) to 34 patients with refractory PTSD-related nightmares and flashbacks (open-label trial [n = 22]; single-blind trial [n = 12]), who had previously received psychiatric treatment for approximately 2-15 years, without therapeutic benefits. The effect of TP was determined using the Clinician-Administered PTSD Scale (CAPS) and the Impact of Event Scale-Revised (IES-R).

RESULTS

Overall, most patients reported an improvement to none or mild on the CAPS for nightmares (88%) and flashbacks (79%).

CONCLUSION

This study is the first to demonstrate the potential efficacy of TP in the treatment of refractory PTSD-related nightmares and flashbacks. Further double-blind, randomized control trials are needed to explore the potential clinical benefits of TP in PTSD.

Prevalence and Detailed Experience of Nightmare and Nightmare Disorder in Chinese University Students

Nightmares influence the mental health of university students, but the prevalence of nightmare and nightmare disorder requires additional documentation. The data of detailed nightmare experience of nightmare disorder and related depressive mood in this population are also scarce. First, a total of 1,451 students in a comprehensive Chinese university were invited to report their nightmare frequency. Sixty-eight patients with nightmare disorder were diagnosed using a semi-structured clinical interview according to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013). Second, 60 patients with nightmare disorder (8 of 68 patients were dismissed due to data incompletion) and 124 gender-matched, healthy students were invited to answer the Nightmare Experience Questionnaire (NEQ) and the Plutchik-van Praag Depression Inventory (PVP). Of 1,451 students, 923 reported nightmares (its annual prevalence was 63.61%), and 68 were diagnosed with nightmare disorder (its prevalence was 4.69%), with a female preponderance. The mean PVP and four NEQ scale scores in patients were higher than those in healthy students. The PVP scores were correlated with NEQ Physical Effect in patients, and with Negative Emotion in healthy students. This is the first report regarding nightmare disorder prevalence and detailed nightmare experience in university students. The findings of a high prevalence of nightmare disorder in women and elevated scores of nightmare experience among patients in the university population might help address the mechanisms and the management of patients with nightmare disorder.

Cognitive Processing Therapy for Posttraumatic Stress Disorder Is Associated with Negligible Change in Subjective and Objective Sleep

Background: Patients receiving Cognitive Processing Therapy (CPT), an evidence based therapy for posttraumatic stress disorder (PTSD), report improved sleep quality. However, the majority of studies have examined residual sleep disturbance via self-report surveys or separate items on PTSD measures. This study examined whether CPT delivered to veterans in a VA setting improved sleep indices using state-of-the-art objective and subjective insomnia measures. Participants: Participants were war veterans with a current PTSD diagnosis scheduled to begin outpatient individual or group CPT at two Veteran's Affairs (VA) locations (n = 37). Methods: Sleep symptom severity was assessed using the recommended research consensus insomnia assessment, the consensus daily sleep diary and actigraphy. PTSD symptomatology pre- and post-treatment were assessed using the Clinician Administered PTSD Scale. Results: A small to moderate benefit was observed for the change in PTSD symptoms across treatment (ES_RMC = .43). Effect sizes for changes on daily sleep diary and actigraphy variables after CPT were found to be negligible (Range ES_RMC = - .16 to .17). Sleep indices remained at symptomatic clinical levels post-treatment. Discussion: These findings support previous research demonstrating a need for independent clinical attention to address insomnia either before, during, or after PTSD treatment.

Disturbing Dreams and Psychosocial Maladjustment in Children: A Prospective Study of the Moderating Role of Early Negative Emotionality

Although frequent disturbing dreams, including bad dreams and nightmares, have been repeatedly associated with poor psychological well-being in adults, considerably less information exists on their psychosocial correlates in children. Recent empirical and theoretical contributions suggest that the association between disturbing dream frequency and psychosocial adaptation in children may differ as a function of children's negative emotionality. The current study assessed the moderating effect of very early negative emotionality (17 months of age) in the relation between disturbing dream frequency and psychosocial maladjustment (i.e., externalizing + internalizing behaviors) in a sample of 173 11-year-old children. Mixed-model analyses revealed that disturbing dream frequency was associated with some internalizing behaviors but that the association between disturbing dream frequency and most externalizing behaviors was moderated by early negative emotionality. The latter result indicates that the relation between disturbing dream frequency and externalizing behaviors was significant in 11-year-old children showing moderate negative emotionality early in life, but particularly strong in those children with high early negative emotionality. Whereas, a moderating effect of early negative emotionality was not found between disturbing dream frequency and internalizing behaviors, the findings highlight the more specific role of early emotional negativity as a developmental moderator for the link between disturbing dreams and externalizing behaviors in children. The results are discussed in light of recent models of disturbed dreaming production.

Stability of nightmare frequency and its relation to neuroticism: A longitudinal study

Models of nightmare aetiology postulate an interaction between trait and state factors. However, most of the studies that support these models have been cross-sectional and longitudinal studies are scarce. The present data were obtained from N = 888 participants completing two online dream studies carried out independently with the same online panel 2 years apart. Nightmare frequency declined over the 2-year period and these changes were related to changes in neuroticism. The effect of current psychopathology (state aspect) on nightmare frequency was significant but much smaller compared to the effect of previously measured nightmare frequency (trait aspect) and, thus, the study provided empirical evidence for diathesis-stress models. Future longitudinal studies should take a closer look at life events and other factors that increase and/or decrease nightmare frequencies.

Fear in dreams and in wakefulness: Evidence for day/night affective homeostasis

Recent neuroscientific theories have proposed that emotions experienced in dreams contribute to the resolution of emotional distress and preparation for future affective reactions. We addressed one emerging prediction, namely that experiencing fear in dreams is associated with more adapted responses to threatening signals during wakefulness. Using a stepwise approach across two studies, we identified brain regions activated when experiencing fear in dreams and showed that frightening dreams modulated the response of these same regions to threatening stimuli during wakefulness. Specifically, in Study 1, we performed serial awakenings in 18 participants recorded throughout the night with high‐density electroencephalography (EEG) and asked them whether they experienced any fear in their dreams. Insula and midcingulate cortex activity increased for dreams containing fear. In Study 2, we tested 89 participants and found that those reporting higher incidence of fear in their dreams showed reduced emotional arousal and fMRI response to fear‐eliciting stimuli in the insula, amygdala and midcingulate cortex, while awake. Consistent with better emotion regulation processes, the same participants displayed increased medial prefrontal cortex activity. These findings support that emotions in dreams and wakefulness engage similar neural substrates, and substantiate a link between emotional processes occurring during sleep and emotional brain functions during wakefulness.

Predicting the affective tone of everyday dreams: A prospective study of state and trait variables

Although emotions are reported in a large majority of dreams, little is known about the factors that account for night-to-night and person-to-person variations in people’s experience of dream affect. We investigated the relationship between waking trait and state variables and dream affect by testing multilevel models intended to predict the affective valence of people’s everyday dreams. Participants from the general population completed measures of personality and trauma history followed by a three-week daily journal in which they noted dream recall, valence of dreamed emotions and level of perceived stress for the day as well as prior to sleep onset. Within-subject effects accounted for most of the explained variance in the reported valence of dream affect. Trait anxiety was the only variable that significantly predicted dream emotional valence at the between-subjects level. In addition to highlighting the need for more fine-grained measures in this area of research, our results point to methodological limitations and biases associated with retrospective estimates of general dream affect and bring into focus state variables that may best explain observed within-subject variance in emotions experienced in everyday dreams.

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.

Nightmares and Stress: A Longitudinal Study

STUDY OBJECTIVES

In nightmare etiology, trait and state factors play important roles. However, the interaction of state and trait factors has never been studied in a longitudinal design.

METHODS

The current sample included 406 pregnant women who were followed up approximately 6 months after giving birth (n = 375) and 4 years later (n = 302). A nightmare frequency scale and several stress-related questionnaires were presented at three measurement points.

RESULTS

Despite the major life events in this sample, nightmare frequency was very stable over this time period and decreased slightly. In line with previous findings, cross-sectional analyses showed that stressors were associated with current nightmare frequency but longitudinal analyses indicated that previously measured nightmare frequency showed even stronger effects on current nightmare frequency.

CONCLUSIONS

Because the nightmare frequencies were very stable, it would be desirable to carry out intervention studies treating nightmares as early as possible-even in childhood-and study whether nightmare occurrence is lower even years after the intervention.

CITATION

Schredl M, Gilles M, Wolf I, Peus V, Scharnholz B, Sütterlin M, Bardtke S, Send TS, Samaras A, Deuschle M. Nightmares and stress: a longitudinal study. J Clin Sleep Med. 2019;15(9):1209-1215.

Nightmare Severity Is Inversely Related to Frontal Brain Activity During Waking State Picture Viewing

STUDY OBJECTIVES

Growing evidence suggests that nightmares have considerable adverse effects on waking behavior, possibly by increasing post-sleep negative emotions. Dysphoric reactions to nightmares are one component of nightmare severity for which the neural correlates are unknown. Here, we investigate possible neural correlates of nightmare severity in a sample of individuals who frequently recall nightmares.

METHODS

Our principal measure of nightmare severity is nightmare distress as indexed by the Nightmare Distress Questionnaire (NDQ), and secondary measures are retrospective and prospective estimates of frequency of recalling dysphoric dreams (DD). We used high-resolution technetium 99m ethyl cysteinate dimer single photon emission computed tomography to assess regional cerebral blood flow (rCBF) while 18 individuals who were frequent nightmare recallers viewed negative and neutral pictures from the International Affective Picture System. We correlated rCBF with NDQ scores and DD recall frequency estimates.

RESULTS

Negative correlations were observed between NDQ scores and rCBF during negative picture viewing in bilateral insula and anterior cingulate, right medial frontal gyrus, bilateral superior temporal gyrus, right inferior frontal and precentral gyri, and bilateral putamen. Retrospective DD recall correlated with rCBF activity primarily in regions overlapping those related to NDQ scores. Prospective DD recall was only weakly related to rCBF. Results for the neutral condition overlapped partially with those for the negative condition; in particular, NDQ and retrospective DD recall were related to rCBF in medial prefrontal and anterior cingulate gyri.

CONCLUSIONS

Results point to a possible overlap in brain mechanisms involved in nightmare dysphoria (during sleep) and distress (during wakefulness) among individuals who frequently recall nightmares. They provide partial support for a neurocognitive model of nightmares.

COMMENTARY

A commentary on this article appears in this issue on page 179.

Aetiology and treatment of nightmare disorder: State of the art and future perspectives

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.

Management of Post-Traumatic Nightmares: a Review of Pharmacologic and Nonpharmacologic Treatments Since 2013

PURPOSE OF REVIEW

Post-traumatic nightmares (PTN) are a common and enduring problem for individuals with post-traumatic stress disorder (PTSD) and other clinical presentations. PTN cause significant distress, are associated with large costs, and are an independent risk factor for suicide. Pharmacological and non-pharmacological treatment options for PTN exist. A previous review in this journal demonstrated that Prazosin, an alpha blocker, was a preferred pharmacological treatment for PTN and imagery rescripting therapy (IRT) was a preferred non-pharmacological treatment. Since that time, new and important research findings create the need for an updated review.

RECENT FINDINGS

Based on the results of a recent study in the New England Journal of Medicine, Prazosin has been downgraded by both the American Academy of Sleep Medicine (AASM) and the Veterans Health Administration/Department of Defense (VA/DoD) for PTN. In Canada, Nabilone, a synthetic cannabinoid, appears to be promising. Few recent studies have been published on non-pharmacological interventions for PTN; however, recent data is available with regard to using IRT on an inpatient setting, with German combat veterans, and through the use of virtual technology. Recent evidence supports the use of exposure, relaxation, and rescripting therapy (ERRT) with children and individuals with comorbid bipolar disorder and PTN. Prazosin is no longer considered a first-line pharmacological intervention for PTN by AASM and VA/DoD. However, in the absence of a suitable alternative, it will likely remain the preferred option of prescribers. IRT and ERRT remain preferred non-pharmacological treatments of PTN. Combining cognitive behavior therapy for insomnia (CBT-I) with IRT or ERRT may lead to improved outcomes.

Sleep spindles are altered in early- but not late-onset nightmare recallers

Nightmares are a common sleep disorder, defined as highly disturbing mentation which usually awakens the individual from rapid eye movement (REM) sleep. While nightmares are mainly a REM sleep phenomenon, Picard-Deland et al., (2017) recently showed an association between nightmare recall and sleep spindles, which are a non-rapid eye movement (NREM) oscillatory feature. Their results pointed to fewer slow spindles and a higher oscillatory frequency for fast spindles among frequent nightmare recallers compared with controls. To test the suggestion that nightmares stem from changes to emotional neural circuits arising in early childhood (Nielsen, 2017), including early changes in sleep spindles (Scholle et al., 2007), we investigated if the spindle features of early-onset nightmare recallers (ie, recalling nightmares since childhood) (N = 22), differed from those of late-onset nightmare recallers (ie, since adolescence or adulthood) (N = 11), or from those of controls (N = 23). A retrospective analysis of the sleep spindles of 56 participants who had undergone a polysomnographically-recorded morning nap revealed that Early starters uniquely exhibited lower slow spindle densities in five of six derivations (all p < 0.045) and higher fast spindle frequencies in all six derivations (all p < 0.015). These results add precision to previously reported findings for Nightmare recallers: spindle differences are shown to hold only for Early starters. The lifelong occurrence of nightmares may be closely tied to disruptions in the normal development of spindle generation processes occurring early in development.

Spotlight on dream recall: the ages of dreams

Brain and sleep maturation covary across different stages of life. At the same time, dream generation and dream recall are intrinsically dependent on the development of neural systems. The aim of this paper is to review the existing studies about dreaming in infancy, adulthood, and the elderly stage of life, assessing whether dream mentation may reflect changes of the underlying cerebral activity and cognitive processes. It should be mentioned that some evidence from childhood investigations, albeit still weak and contrasting, revealed a certain correlation between cognitive skills and specific features of dream reports. In this respect, infantile amnesia, confabulatory reports, dream-reality discerning, and limitation in language production and emotional comprehension should be considered as important confounding factors. Differently, growing evidence in adults suggests that the neurophysiological mechanisms underlying the encoding and retrieval of episodic memories may remain the same across different states of consciousness. More directly, some studies on adults point to shared neural mechanisms between waking cognition and corresponding dream features. A general decline in the dream recall frequency is commonly reported in the elderly, and it is explained in terms of a diminished interest in dreaming and in its emotional salience. Although empirical evidence is not yet available, an alternative hypothesis associates this reduction to an age-related cognitive decline. The state of the art of the existing knowledge is partially due to the variety of methods used to investigate dream experience. Very few studies in elderly and no investigations in childhood have been performed to understand whether dream recall is related to specific electrophysiological pattern at different ages. Most of all, the lack of longitudinal psychophysiological studies seems to be the main issue. As a main message, we suggest that future longitudinal studies should collect dream reports upon awakening from different sleep states and include neurobiological measures with cognitive performances.

Relationships between sleep paralysis and sleep quality: current insights

Sleep paralysis is the unusual experience of waking up in the night without the ability to move. Currently little is known about the experience, despite the fact that the vast majority of episodes are associated with extreme fear and in a minority of cases can lead to clinically significant levels of distress. The aim of this work was to review the existing literature pertaining to the relationship sleep paralysis has to sleep more generally, measured both with subjective questionnaires and objective laboratory recordings. In terms of subjective sleep variables, worse sleep quality has been found in multiple studies to be associated with increased odds of sleep paralysis occurrence. In addition, insomnia symptoms (but not a diagnosed insomnia disorder) have also been found to predict sleep paralysis. Associations between sleep paralysis and other unusual and/or threatening sleep experiences such as nightmares, exploding head syndrome, and lucid dreaming have been reported. In terms of objective measurements, the limited literature to date shows sleep paralysis to be a "mixed" state of consciousness, combining elements of rapid eye movement sleep with elements of wakefulness. Future research needs to focus on longitudinal designs to disentangle the direction of effects and more typically employ a broader assessment of sleep paralysis that better captures associated features such as hallucinations, fear, and distress.

REM Sleep Theta Changes in Frequent Nightmare Recallers

Study Objectives

To replicate and expand upon past research by evaluating sleep and wake electroencephalographic spectral activity in samples of frequent nightmare (NM) recallers and healthy controls.

Methods

Computation of spectral activity for sleep (non-REM and REM) and wake electroencephalogram recordings from 18 frequent NM recallers and 15 control participants.

Results

There was higher "slow-theta" (2-5 Hz) for NM recallers than for controls during wake, non-REM sleep and REM sleep. Differences were clearest for frontal and central derivations and for REM sleep cycles 2-4. There was also higher beta activity during NREM sleep for NM recallers. Findings partially replicate past research by demonstrating higher relative "slow-theta" (3-4Hz) for NM recallers than for controls.

Conclusions

Findings are consistent with a neurocognitive model of nightmares that stipulates cross-state anomalies in emotion processing in NM-prone individuals.