Sleep and REM sleep disturbance in the pathophysiology of PTSD: the role of extinction memory

Enhancing post-traumatic stress disorder patient assessment: leveraging natural language processing for research of domain criteria identification using electronic medical records

BACKGROUND

Extracting research of domain criteria (RDoC) from high-risk populations like those with post-traumatic stress disorder (PTSD) is crucial for positive mental health improvements and policy enhancements. The intricacies of collecting, integrating, and effectively leveraging clinical notes for this purpose introduce complexities.

METHODS

In our study, we created a natural language processing (NLP) workflow to analyze electronic medical record (EMR) data and identify and extract research of domain criteria using a pre-trained transformer-based natural language model, all-mpnet-base-v2. We subsequently built dictionaries from 100,000 clinical notes and analyzed 5.67 million clinical notes from 38,807 PTSD patients from the University of Pittsburgh Medical Center. Subsequently, we showcased the significance of our approach by extracting and visualizing RDoC information in two use cases: (i) across multiple patient populations and (ii) throughout various disease trajectories.

RESULTS

The sentence transformer model demonstrated high F1 macro scores across all RDoC domains, achieving the highest performance with a cosine similarity threshold value of 0.3. This ensured an F1 score of at least 80% across all RDoC domains. The study revealed consistent reductions in all six RDoC domains among PTSD patients after psychotherapy. We found that 60.6% of PTSD women have at least one abnormal instance of the six RDoC domains as compared to PTSD men (51.3%), with 45.1% of PTSD women with higher levels of sensorimotor disturbances compared to men (41.3%). We also found that 57.3% of PTSD patients have at least one abnormal instance of the six RDoC domains based on our records. Also, veterans had the higher abnormalities of negative and positive valence systems (60% and 51.9% of veterans respectively) compared to non-veterans (59.1% and 49.2% respectively). The domains following first diagnoses of PTSD were associated with heightened cue reactivity to trauma, suicide, alcohol, and substance consumption.

CONCLUSIONS

The findings provide initial insights into RDoC functioning in different populations and disease trajectories. Natural language processing proves valuable for capturing real-time, context dependent RDoC instances from extensive clinical notes.

Infralimbic activity during REM sleep facilitates fear extinction memory

Rapid eye movement (REM) sleep is known to facilitate fear extinction and play a protective role against fearful memories.1,2 Consequently, disruption of REM sleep after a traumatic event may increase the risk for developing PTSD.3,4 However, the underlying mechanisms by which REM sleep promotes extinction of aversive memories remain largely unknown. The infralimbic cortex (IL) is a key brain structure for the consolidation of extinction memory.5 Using calcium imaging, we found in mice that most IL pyramidal neurons are intensively activated during REM sleep. Optogenetically suppressing the IL specifically during REM sleep within a 4-h window after auditory-cued fear conditioning impaired extinction memory consolidation. In contrast, REM-specific IL inhibition after extinction learning did not affect the extinction memory. Whole-cell patch-clamp recordings demonstrated that inactivating IL neurons during REM sleep depresses their excitability. Together, our findings suggest that REM sleep after fear conditioning facilitates fear extinction by enhancing IL excitability and highlight the importance of REM sleep in the aftermath of traumatic events for protecting against traumatic memories.

REM disruption and REM Vagal Activity Predict Extinction Recall in Trauma-Exposed Individuals

Accumulating evidence suggests that rapid eye movement sleep (REM) supports the consolidation of extinction memory. REM is disrupted in PTSD, and REM abnormalities after traumatic events increase the risk of developing PTSD. Therefore, it was hypothesized that abnormal REM in trauma-exposed individuals may pave the way for PTSD by interfering with the processing of extinction memory. In addition, PTSD patients display reduced vagal activity. Vagal activity contributes to the strengthening of memories, including fear extinction memory, and recent studies show that the role of vagus in memory processing extends to memory consolidation during sleep. Therefore, it is plausible that reduced vagal activity during sleep in trauma-exposed individuals may be an additional mechanism that impairs extinction memory consolidation. However, to date, the contribution of sleep vagal activity to the consolidation of extinction memory or any emotional memory has not been investigated. To test these hypotheses, we examined the association of extinction memory with REM characteristics and REM vagal activity (indexed as heart rate variability) in a large sample of trauma-exposed individuals (n=113). Consistent with our hypotheses, REM disruption was associated with poorer physiological and explicit extinction memory. Furthermore, higher vagal activity during REM was associated with better explicit extinction memory, and physiological extinction memory in males. These findings support the notion that abnormal REM may contribute to PTSD by impairing the consolidation of extinction memory and indicate the potential utility of interventions that target REM sleep characteristics and REM vagal activity in fear-related disorders.

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.

A phase 3, randomized, placebo-controlled, trial to evaluate the efficacy and safety of bedtime sublingual cyclobenzaprine (TNX-102 SL) in military-related posttraumatic stress disorder

Sleep disturbances in posttraumatic stress disorder (PTSD) are a potential target for improving PTSD severity with pharmacotherapy. TNX-102 SL is a bedtime sublingual formulation of cyclobenzaprine with potent binding and antagonist activity at 5-HT2A, α1-adrenergic, H1 histaminergic, and M1 muscarinic receptors, which play roles in the pharmacological management of sleep disturbances. This Phase 3 trial evaluated the efficacy and safety of TNX-102 SL in patients with military-related PTSD. Early and sustained improvements in sleep were associated with TNX-102 SL treatment by PROMIS Sleep Disturbance scale and Clinician Administered PTSD Scale (CAPS-5) "sleep disturbance" item, establishing a sleep quality benefit. Primary analysis comparing change from baseline in CAPS-5 total severity between TNX-102 SL and placebo at week 12 was not significant; however, week 4 was associated with an improvement. Secondary analyses showed TNX-102 SL treatment was associated with benefits on the Clinician Global Impression of Improvement at week 4 and the Patient Global Impression of Change at week 12. Time since trauma exposure was a discriminator of CAPS-5 treatment response in the subgroup ≤ 9 years since the index event. This study provides preliminary evidence that TNX-102 SL is well-tolerated and may promote recovery from PTSD by addressing sleep-related symptoms.

Independent and Joint Associations of Physical Activity and Sleep on Mental Health Among a Global Sample of 200,743 Adults

BACKGROUND

Previous research has demonstrated that both sleep and physical activity (PA) are independently associated with various indicators of mental health among adults. However, their joint contribution to mental health has received limited attention. The present study used cross-sectional data from the Mental Health Million Project to examine the independent and joint effects of sleep and PA on mental health among a global sample of adults, and whether these effects differ among individuals receiving mental health treatment.

METHOD

The sample included 200,743 participants (33.1% young adults, 45.6% middle-aged adults, 21.3% older adults; 57.6% females, 0.9% other) from 213 countries, territories, and archipelagos worldwide that completed a comprehensive 47-item assessment of mental health including both problems (i.e., ill-being) and assets (i.e., well-being): the Mental Health Quotient. Participants also reported their weekly frequency of PA and adequate sleep, and mental health treatment status. A series of generalized linear mixed models were computed.

RESULTS

Independent dose-response associations were observed, whereby greater amounts of PA and adequate sleep were each associated with better mental health. In addition, a synergistic interaction was observed in which the positive correlation of PA with mental health was strengthened with greater frequency of adequate sleep. These benefits were less pronounced among adults receiving mental health treatment.

CONCLUSION

While findings suggest sleep can help to offset the negative influence of a physically inactive lifestyle (and vice versa), our results point to a "more is better" approach for both behaviors when it comes to promoting mental health.

Evaluation of sleep and therapeutic education needs of military with PTSD

Sleep disorders in post-traumatic stress disorder (PTSD) are both diagnostic (nocturnal reliving) and prognostic. Poor sleep worsens the daytime symptomatology of PTSD and makes it resistant to treatment. However, no specific treatment is codified in France to treat these sleep disorders although sleep therapies (cognitive behavioural therapy for insomnia, psychoeducation and relaxation) have proven for years to be effective in treating insomnia. Therapeutic sessions can be part of a therapeutic patient education program, which is a model for the management of chronic pathologies. It allows for an improvement in a patient's quality of life and enhanced medication compliance. We therefore carried out an inventory of sleep disorders of patients with PTSD. First, we collected data by means of sleep diaries concerning the population's sleep disorders at home. Then we assessed the population's expectations and needs regarding its management of sleep, thanks to a semi-qualitative interview. The data from sleep diaries, which was consistent with the literature, showed that our patients suffered from severe sleep disorders that strongly impact their daily lives, with 87% of patients having an increased sleep onset latency, and 88% having nightmares. We observed a strong demand from patients for specific support for these symptoms, 91% expressing an interest in a TPE program targeting sleep disorders. Thanks to the data collected, the emerging themes for a future therapeutic patient education program targeting sleep disorders of soldiers with PTSD are: sleep hygiene; management of nocturnal awakenings, including nightmares; and psychotropic drugs.

To "feel" better, sleep on it!

Emotional memories are consolidated during REM sleep.

Blunted Glucocorticoid Responsiveness to Stress Causes Behavioral and Biological Alterations That Lead to Posttraumatic Stress Disorder Vulnerability

BACKGROUND

Understanding why only a subset of trauma-exposed individuals develop posttraumatic stress disorder is critical for advancing clinical strategies. A few behavioral (deficits in fear extinction) and biological (blunted glucocorticoid levels, small hippocampal size, and rapid-eye-movement sleep [REMS] disturbances) traits have been identified as potential vulnerability factors. However, whether and to what extent these traits are interrelated and whether one of them could causally engender the others are not known.

METHODS

In a genetically selected rat model of reduced corticosterone responsiveness to stress, we explored posttraumatic stress disorder-related biobehavioral traits using ex vivo magnetic resonance imaging, cued fear conditioning, and polysomnographic recordings combined with in vivo photometric measurements.

RESULTS

We showed that genetic selection for blunted glucocorticoid responsiveness led to a correlated multitrait response, including impaired fear extinction (observed in males but not in females), small hippocampal volume, and REMS disturbances, supporting their interrelatedness. Fear extinction deficits and concomitant disruptions in REMS could be normalized through postextinction corticosterone administration, causally implicating glucocorticoid deficiency in two core posttraumatic stress disorder-related risk factors and manifestations. Furthermore, reduced REMS was accompanied by higher norepinephrine levels in the hippocampal dentate gyrus that were also reversed by postextinction corticosterone treatment.

CONCLUSIONS

Our results indicate a predominant role for glucocorticoid deficiency over the contribution of reduced hippocampal volume in engendering both REMS alterations and associated deficits in fear extinction consolidation, and they causally implicate blunted glucocorticoids in sustaining neurophysiological disturbances that lead to fear extinction deficits.

The Ponto-Geniculo-Occipital (PGO) Waves in Dreaming: An Overview

Rapid eye movement (REM) sleep is the main sleep correlate of dreaming. Ponto-geniculo-occipital (PGO) waves are a signature of REM sleep. They represent the physiological mechanism of REM sleep that specifically limits the processing of external information. PGO waves look just like a message sent from the pons to the lateral geniculate nucleus of the visual thalamus, the occipital cortex, and other areas of the brain. The dedicated visual pathway of PGO waves can be interpreted by the brain as visual information, leading to the visual hallucinosis of dreams. PGO waves are considered to be both a reflection of REM sleep brain activity and causal to dreams due to their stimulation of the cortex. In this review, we summarize the role of PGO waves in potential neural circuits of two major theories, i.e., (1) dreams are generated by the activation of neural activity in the brainstem; (2) PGO waves signaling to the cortex. In addition, the potential physiological functions during REM sleep dreams, such as memory consolidation, unlearning, and brain development and plasticity and mood regulation, are discussed. It is hoped that our review will support and encourage research into the phenomenon of human PGO waves and their possible functions in dreaming.

Sleep and mental health in recruit paramedics: a 6-month longitudinal study

STUDY OBJECTIVES

To explore potential relationships and longitudinal changes in sleep and mental health in recruit paramedics over the first 6 months of work, and whether sleep disturbances pre-emergency work predict future mental health outcomes.

METHODS

Participants (N = 101, 52% female, Mage = 26 years) completed questionnaires prior to (baseline), and after 6 months of emergency work to assess for symptoms of insomnia, obstructive sleep apnea, post-traumatic stress disorder (PTSD), depression, anxiety, and trauma exposure. At each timepoint, participants also completed a sleep diary and wore an actigraph for 14 days to assess sleep patterns. Correlations between baseline sleep and mental health were conducted and changes in these variables across timepoints were examined using linear mixed models. Hierarchical regressions assessed whether sleep at baseline predicted mental health at follow-up.

RESULTS

Insomnia and depression symptoms, and total sleep time increased while sleep onset latency decreased across the first 6 months of emergency work. Participants experienced an average of 1 potentially traumatic event during the 6-month period. Baseline insomnia predicted increased depression symptoms at the 6-month follow-up, while baseline wake after sleep onset predicted follow-up PTSD symptoms.

CONCLUSION

Results highlight an increase in insomnia and depression across the initial months of emergency work, while sleep disturbances before emergency work were identified as potential risk factors for the development of depression and PTSD among paramedics in their early career. Screening and early interventions targeting poor sleep at the beginning of emergency employment may assist in reducing the risk of future mental health outcomes in this high-risk occupation.

Sleep and vigilance states: Embracing spatiotemporal dynamics

The classic view of sleep and vigilance states is a global stationary perspective driven by the interaction between neuromodulators and thalamocortical systems. However, recent data are challenging this view by demonstrating that vigilance states are highly dynamic and regionally complex. Spatially, sleep- and wake-like states often co-occur across distinct brain regions, as in unihemispheric sleep, local sleep in wakefulness, and during development. Temporally, dynamic switching prevails around state transitions, during extended wakefulness, and in fragmented sleep. This knowledge, together with methods monitoring brain activity across multiple regions simultaneously at millisecond resolution with cell-type specificity, is rapidly shifting how we consider vigilance states. A new perspective incorporating multiple spatial and temporal scales may have important implications for considering the governing neuromodulatory mechanisms, the functional roles of vigilance states, and their behavioral manifestations. A modular and dynamic view highlights novel avenues for finer spatiotemporal interventions to improve sleep function.

Sleep efficiency predicts improvements in fear extinction and PTSD symptoms during prolonged exposure for veterans with comorbid insomnia

Prolonged exposure (PE) is an evidenced-based psychotherapy for PTSD, but many Veterans fail to achieve a clinically meaningful response. Sleep issues are prevalent in Veterans and may interfere with PE by disrupting the learning and consolidation of fear extinction memories during PE exposures. Here, we examined whether changes in fear extinction across imaginal exposures and PTSD symptoms during PE were predicted by diary-assessed levels of nightly sleep efficiency (SE; i.e., percent of time in bed spent sleeping), which may indirectly index sleep fragmentation and sleep-facilitated memory processes. Participants were Veterans with PTSD and comorbid insomnia (N = 40) participating in a clinical trial of cognitive-behavioral therapy for insomnia plus PE. SE was measured via nightly sleep diaries, fear extinction was operationalized as a reduction in peak distress between weekly imaginal exposures, and PTSD symptoms were assessed bi-weekly. Cross-lagged panel models revealed that higher sleep efficiency during the week predicted lower peak distress at the subsequent imaginal exposure and lower PTSD symptoms at the subsequent assessment, whereas PTSD symptoms and peak distress did not predict subsequent sleep efficiency. Efficient sleep may facilitate fear extinction and PTSD reduction during PE. Targeting sleep efficiency could improve PE effectiveness for Veterans with comorbid insomnia.

Role of pontine sub-laterodorsal tegmental nucleus (SLD) in rapid eye movement (REM) sleep, cataplexy, and emotion

Pontine sub-laterodorsal tegmental nucleus (SLD) is crucial for REM sleep. However, the necessary role of SLD for REM sleep, cataplexy that resembles REM sleep, and emotion memory by REM sleep has remained unclear. To address these questions, we focally ablated SLD neurons using adenoviral diphtheria-toxin (DTA) approach and found that SLD lesions completely eliminated REM sleep accompanied by wake increase, significantly reduced baseline cataplexy amounts by 40% and reward (sucrose) induced cataplexy amounts by 70% and altered cataplexy EEG Fast Fourier Transform (FFT) from REM sleep-like to wake-like in orexin null (OXKO) mice. We then used OXKO animals with absence of REM sleep and OXKO controls and examined elimination of REM sleep in anxiety and fear extinction. Our resulted showed that REM sleep elimination significantly increased anxiety-like behaviors in open field test (OFT), elevated plus maze test (EPM) and defensive aggression and impaired fear extinction. The data indicate that in OXKO mice the SLD is the sole generator for REM sleep; (2) the SLD selectively mediates REM sleep cataplexy (R-cataplexy) that merges with wake cataplexy (W-cataplexy); (3) REM sleep enhances positive emotion (sucrose induced cataplexy) response, reduces negative emotion state (anxiety), and promotes fear extinction.

Sleep timing, chronotype, and posttraumatic stress disorder: An individual participant data meta-analysis

Sleep disturbance is a major component of posttraumatic stress disorder (PTSD). The role of circadian disruption is largely overlooked, though many PTSD studies collect proxy markers of circadian timing. This individual participant data (IPD) meta-analysis examined the correlation between sleep timing / chronotype and PTSD severity among individuals diagnosed with PTSD, the standardized mean difference in sleep timing / chronotype for individuals with and without PTSD, and moderators of these relationships. A systematic search was conducted; authors provided IPD for 27 studies and aggregate data for 16 studies (3,011 participants with PTSD; 2,703 participants without PTSD). Two-step meta-analyses were conducted using a random-effects multivariate approach with robust variance estimation. Bedtime and wake time were not significantly associated with PTSD symptoms or diagnosis. Less total sleep time / time in bed was weakly associated with greater PTSD symptoms. Moderator analyses revealed that effect sizes were stronger in certain populations and when using wrist actigraphy to measure sleep timing; however, gap maps revealed few studies in moderator categories with the strongest effects. Only two studies measured chronotype, prohibiting strong conclusions. Our findings indicate that the relationship between sleep timing and PTSD is weak; however, key gaps in the literature warrant further study.

The role of positive affect processes in the association between posttraumatic stress disorder symptoms and sleep: A multi-study design

OBJECTIVES

Posttraumatic stress disorder (PTSD) symptoms have been linked to sleep disturbances. Limited work has explored how positive affect processes may account for this relationship. Advancing research in this area, we utilized a multi-study design to investigate the role of positive affect processes (levels of positive affect, positive emotionality, hedonic deficits, negative affect interference) in the PTSD-sleep association.

METHODS

Data from 149 trauma-exposed firefighters (M_age = 38.93 ± 9.65, 5.40 % women) were collected between September 2021 and November 2021, and data from 119 trauma-exposed community members (M_age = 29.60 ± 8.67, 68.10 % women) were collected between February 2021 and December 2021. Participants completed an online survey on PTSD symptoms, sleep disturbances, and positive affect processes.

RESULTS

Positive affect levels (b = 0.03, 95 % confidence interval [CI] [0.01, 0.06]; firefighter sample), positive emotionality (b = 0.07, CI [0.03, 0.13]; community sample), and negative affect interference (b = 0.06, CI [0.01, 0.14]; community sample) significantly accounted for the associations between PTSD symptom severity and sleep disturbances controlling for the effects of gender and age.

CONCLUSION

Findings highlight the role of positive affect processes in the link between PTSD and sleep, and support addressing positive affect processes as potential targets in clinical interventions for co-occurring PTSD-sleep problems.

Evaluation of Correlation between Sleep and Psychiatric Disorders in a Population of Night Shift Workers: A Pilot Study

BACKGROUND

Insomnia is the perception of inadequate, insufficient or non-restorative sleep. Of all sleep-related disorders, insomnia is the most common. It is important to remember that the sleep-wake cycle also plays a central role in the genesis of anxiety and depression. The aim of our study is to evaluate the association between sleep disturbances and anxiety and depression in a group of workers of both sexes who perform night shift work.

METHODS

Information on sleep disorders was collected by administering the Insomnia Severity Index (ISI) questionnaire. Statistical analysis was conducted using the Chi-square test to assess whether there were any differences between sex for those who were healthy or who were diagnosed with psychiatric disorders.

RESULTS

The results showed that there was a good percentage of subjects with insomnia problems, impairing normal daily activities and promoting the onset of fatigue, daytime sleepiness, cognitive performance deficits and mood disorders.

CONCLUSION

We highlighted how anxious and depressive anxiety disorders are more pronounced in people who suffer from altered sleep-wake rhythms. Further research in this direction could prove to be fundamental for understanding the genesis of the onset of other disorders as well.

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.

Rapid eye movement sleep parasympathetic activity predicts wake hyperarousal symptoms following a traumatic event

Heart rate variability (HRV) can be used to assess changes in output of the parasympathetic nervous system (PNS). Considering that patients with post-traumatic stress disorder (PTSD) often experience disturbances in sleep, arousal, and autonomic functioning, we sought to explore the association of PNS activity during sleep with hyperarousal symptoms of PTSD. Because a broad literature supports the importance of rapid eye movement (REM) sleep in PTSD, REM-sleep features were specifically examined as predictors of PTSD symptom severity. A total of 90 participants, primarily civilian and female, aged 18-40 years who had experienced a traumatic event in the last 2 years, underwent an ambulatory polysomnography (PSG) acclimation night followed by a second PSG night from which sleep physiological measures were computed. Participants underwent an ambulatory polysomnography (PSG) acclimation night followed by a second PSG night from which sleep physiological measures were computed. PTSD severity was measured using the PTSD Checklist for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (PCL-5). Dependent variables were total PCL-5 score as well as its hyperarousal symptom subscore. Predictors included REM latency, percentage, density, segment length, and an index of parasympathetic tone (root mean square of the successive differences in the R-R interval or RMSSD). Hierarchical regression models were conducted to analyse the association of REM features with PCL-5 total and hyperarousal subscales. Using hierarchical regression, REM-sleep RMSSD accounted for a significant proportion of the variation in outcome variables, even when accounting for other REM-sleep features. The present findings support hypothesised relationships between PTSD symptomatology and REM-sleep physiology and, specifically, that lowered parasympathetic tone in REM may be an important associate of the hyperarousal symptom cluster in PTSD.

Metabotropic glutamate receptor function and regulation of sleep-wake cycles

Metabotropic glutamate (mGlu) receptors are the most abundant family of G-protein coupled receptors and are widely expressed throughout the central nervous system (CNS). Alterations in glutamate homeostasis, including dysregulations in mGlu receptor function, have been indicated as key contributors to multiple CNS disorders. Fluctuations in mGlu receptor expression and function also occur across diurnal sleep-wake cycles. Sleep disturbances including insomnia are frequently comorbid with neuropsychiatric, neurodevelopmental, and neurodegenerative conditions. These often precede behavioral symptoms and/or correlate with symptom severity and relapse. Chronic sleep disturbances may also be a consequence of primary symptom progression and can exacerbate neurodegeneration in disorders including Alzheimer's disease (AD). Thus, there is a bidirectional relationship between sleep disturbances and CNS disorders; disrupted sleep may serve as both a cause and a consequence of the disorder. Importantly, comorbid sleep disturbances are rarely a direct target of primary pharmacological treatments for neuropsychiatric disorders even though improving sleep can positively impact other symptom clusters. This chapter details known roles of mGlu receptor subtypes in both sleep-wake regulation and CNS disorders focusing on schizophrenia, major depressive disorder, post-traumatic stress disorder, AD, and substance use disorder (cocaine and opioid). In this chapter, preclinical electrophysiological, genetic, and pharmacological studies are described, and, when possible, human genetic, imaging, and post-mortem studies are also discussed. In addition to reviewing the important relationships between sleep, mGlu receptors, and CNS disorders, this chapter highlights the development of selective mGlu receptor ligands that hold promise for improving both primary symptoms and sleep disturbances.

Longitudinal associations between PTSD and sleep disturbances among World Trade Center responders

OBJECTIVE/BACKGROUND

Post-traumatic stress disorder (PTSD) is characterized by substantial disruptions in sleep quality, continuity, and depth. Sleep problems also may exacerbate PTSD symptom severity. Understanding how PTSD and sleep may reinforce one another is critical for informing effective treatments.

PATIENTS/METHODS

In a sample of 452 World Trade Center 9/11 responders (mean age = 55.22, 89.4% male, 66.1% current or former police), we examined concurrent and cross-lagged associations between PTSD symptom severity, insomnia symptoms, nightmares, and sleep quality at 3 time points ∼1 year apart. Data were analyzed using random intercept cross-lagged panel models.

RESULTS

PTSD symptom severity and sleep variables were relatively stable across time (intraclass correlation coefficients: 0.63 to 0.84). Individuals with more insomnia symptoms, more nightmares, and poorer sleep quality had greater PTSD symptom severity, on average. Within-person results revealed that greater insomnia symptoms and nightmares at Time 1 were concurrently associated with greater PTSD symptoms at Time 1. Insomnia symptoms were also concurrently associated with PTSD symptoms at Times 2 and 3, respectively. Cross-lagged and autoregressive results revealed that PTSD symptoms and nightmares predicted nightmares at the next timepoint.

CONCLUSIONS

Overall, results suggest PTSD and sleep problems may be linked at the same point in time but may not always influence each other longitudinally. Further, individuals who experience more sleep disturbances on average may suffer from more debilitating PTSD. Evidence-based treatments for PTSD may consider incorporating treatment of underlying sleep disturbances and nightmares.

Activation of ventral tegmental area vesicular GABA transporter (Vgat) neurons alleviates social defeat stress-induced anxiety in APP/PS1 mice

Introduction

Alzheimer's disease (AD) is a progressive neurodegenerative disease that results in cognitive impairment and is often accompanied by anxiety. In this study, we investigated whether the activation of VTA^Vgat neurons could reduce anxiety in APP/PS1 mice. We hypothesized that acute social defeat stress (SDS) would lead to anxiety in APP/PS1 mice, and that the activation of VTA^Vgat neurons would alleviate this anxiety.

Methods

We exposed APP/PS1 mice to acute SDS and assessed anxiety using the open field test and elevated plus-arm test. Activated VTA^Vgat neurons was tested by cfos staining. Sleep quality was detected using electroencephalogram after SDS or non-SDS procedure. Sleep duration, sleep latency, and non-rapid eye movement (NREM) percentage were analyzed. VTA^Vgat neurons were chemogenetically activated by deschloroclozapine.

Results

Our results showed that acute SDS led to anxiety in APP/PS1 mice, as evidenced by increased anxiety-related behaviors in the open field and elevated plus-arm tests. Activation of VTA^Vgat neurons by SDS led to an increase in sleep duration, primarily due to a decrease in sleep latency and an increase in NREMs. However, the quality of sleep was poor. Chemogenetical activation of VTA^Vgat neurons improved sleep quality and relieved SDS-induced anxiety. Furthermore, the anxiety state correlated negatively with sleep duration and NREM percentage and correlated positively with theta power density in APP/PS1 mice.

Discussion

Our study provides evidence that the activation of VTA^Vgat neurons alleviates SDS-induced anxiety in APP/PS1 mice, suggesting that poor sleep quality may exacerbate anxiety in AD. These findings may have important implications for the treatment of anxiety in AD, as targeting VTA^Vgat neurons could be a potential therapeutic approach.

Association between the experience of sexual violence and insomnia in a national sample of French adults

PURPOSEL

The experience of sexual violence has been associated with sleeping disorders; however, few studies have examined this association using a large sample of the general population. This study investigates whether lifetime experience of sexual violence and childhood experience of sexual violence are associated with insomnia.

METHODS

Our study is based on data from the 2017 French Health Barometer, a general population phone cross-sectional survey, which included 25 319 adults aged 18-75 years in 2017. Questions regarding sleep quality were asked to 12 560 participants, and insomnia was defined according to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V). We conducted adjusted Log-binomial regressions to examine the association between the experience of sexual violence and insomnia by calculating adjusted Prevalence Ratios (PRa; 95% CI).

RESULTS

The weighted prevalence of insomnia was 13.5%, with women more affected than men (17.9% vs 9.6%). The prevalence of lifetime experience of sexual violence was around 3 times higher among those who suffer from insomnia (12.3%) compared to those who do not (4.5%). The adjusted associations between lifetime experience of sexual violence and insomnia, as well as between childhood experience of sexual violence and insomnia were both statistically significant (PRa = 1.79; 95% CI: 1.59-2.02; and PRa = 1.42; 95% CI: 1.23-1.64 respectively).

CONCLUSIONS

Sexual violence could explain the substantial sex-difference in insomnia. Our findings reiterate the importance of systematically screening for sexual violence among patients suffering from sleep disorders to propose adequate trauma-informed interventions.

How Different Factors in Combination Change Fear Extinction Learning: The Case of Sex and Stress Hormones

Effects of a specific factor on fear extinction or exposure therapy have revealed promising results, for example how sex or stress hormones exert the capability to critically change extinction learning and consolidation processes. However, we must acknowledge that in real life these factors do not operate in isolation, they go hand in hand. In this chapter, the available evidence regarding interactions of sex and stress hormones on extinction processes and exposure therapy will be integrated and discussed. First hints exist that these factors in combination critically target extinction learning and consolidation processes, calling for more detailed research on the exact underlying mechanisms. In addition to experiments with high sample sizes, we must aim for a collaborative effort of laboratories across the whole world to be able to identify critical combinations of factors associated with improved, but also impaired extinction processes and exposure therapy success. We expect that the revelation of further relevant factors will not only be limited to the interplay between sex and stress hormones but will include factors such as sleep and exercise as well. In the long run, uncovering the most important interaction effects will give us critical hints for differential treatment options to be realized in the sense of a personalized medicine approach.

The Impact of Sleep on Fear Extinction

Sleep plays a crucial role in the consolidation of memories, including those for fear acquisition and extinction training. This chapter reviews findings from studies testing this relationship in laboratory, naturalistic, and clinical settings. While evidence is mixed, several studies in humans have linked fear and extinction recall/retention to both rapid eye-movement and slow wave sleep. Sleep appears to further aid in the processing of both simulated and actual trauma and improves psychotherapeutic treatment outcomes in those with anxiety and trauma- and stressor-related disorders. This chapter concludes with a discussion of the current challenges facing sleep and emotional memory research in addition to suggestions for improving future research.

Sleep disturbance during COVID-19: Correlates and predictive ability for mental health symptomatology in a Canadian online sample

BACKGROUND

Sleep disturbance is associated with mental health symptomatology, but this impact is understudied during COVID-19. The aims of this study are to: 1) examine correlates of sleep disturbance, and 2) examine the longitudinal relationship between sleep disturbance and mental health symptoms 6 months later, during the pandemic.

METHODS

Data were analyzed from COVID-19 Survey Canada conducted between May 2020 (T1) and November 2021 (T2) (n = 489). We examined COVID-related baseline correlates of sleep disturbance at T1, and used multivariable regressions to examine the relationship between T1 sleep disturbance and T2 post-traumatic stress (PTS), health anxiety, generalized anxiety, and depressive symptoms, controlling for baseline mental health symptoms and sociodemographics.

RESULTS

Females, ages 30-49, and those with an annual household income <$50,000, showed a higher prevalence of clinically significant sleep disturbance. After adjustment, compared to those without sleep disturbance at baseline, those with sleep disturbance showed a significant increase in PTS symptoms at 6 months (b = 11.80, 95% CI = [8.21-15.38], p < 0.001).

LIMITATIONS

Results are not nationally representative. Data may be subject to response biases due to self-report methods and we are unable to determine causality.

CONCLUSION

Being able to predict adverse mental health implications of sleep disturbance will help clinicians be equipped to target future impacts of the COVID-19 pandemic as well as any future potential pandemics or traumas. This study emphasizes the importance of screening individuals for sleep disturbance.

Sex differences in the effect of subjective sleep on fear conditioning, extinction learning, and extinction recall in individuals with a range of PTSD symptom severity

Sleep has been found to play a key role in fear conditioning, extinction learning and extinction recall, and sleep disturbances are linked to many mental disorders including post-traumatic stress disorder (PTSD). Previous studies examining associations between sleep and fear or extinction processes primarily focused on objectively measured sleep architecture. Little research has so far focused on subjective sleep measures and particularly in clinical populations, which often experience subjectively poor sleep, including PTSD. Here we investigated whether subjective sleep disturbance, sleep onset latency, wake after sleep onset or sleep efficiency were related to fear conditioning, extinction learning or extinction recall in a large sample of individuals with a range of PTSD symptom severity (n = 248). Overall, we did not find that subjective sleep was associated with fear conditioning or extinction processes. However, exploratory analyses examining the moderating effect of sex found that shorter sleep onset latency and greater sleep efficiency were associated with improved extinction recall in women with higher PTSD symptom severity. This suggests that less time falling asleep and longer time asleep while in bed may be protective in highly symptomatic women against the commonly observed impaired extinction recall in PTSD. More studies are needed to explore sex-specific effects further.

Call to action: Addressing sleep disturbances, a hallmark symptom of PTSD, for refugees, asylum seekers, and internally displaced persons

Sleep difficulty is a recognized hallmark symptom of post-traumatic stress disorder (PTSD) yet often remains an enduring and neglected problem post-treatment. Around 4.4%- 88.0% of refugees, asylum seekers, and internally displaced persons report PTSD, of which 39%- 99% report sleep difficulties. These percentages substantially exceed those of the general population. Yet there has been a lack of research examining evidence-based stand-alone and add-on treatments for PTSD and related sleep disturbances among this population. Barriers to treatment encountered by this population often vary by their legal status or location, but generally include lack of access due to insufficient evidence-based treatments or mental health practitioner shortages, lack of psychoeducation on mental health, cultural stigma, language barriers, situational instability, and racial bias. The refugee population has been on the rise over the past 10 years, and the United Nations estimated the recent Ukraine-Russia conflict would lead to an additional 12 million people needing humanitarian assistance inside Ukraine and more than 6.9 million refugees fleeing to neighboring countries in the coming months. Given that refugees, asylum seekers, and internally displaced persons repeatedly encounter barriers to mental health care specific to their predicament, interventions designed to accommodate their situation are imperative for improving their sleep and mental health. We therefore call for there to be more research on integrative programs incorporating evidence-based treatments that allow for scalability, adaptability, and rapid dissemination to maximize impact in this population. Further, we encourage trainings among clinicians and researchers to increase knowledge and confidence in working with this population.

Global dissociation of the posterior amygdala from the rest of the brain during REM sleep

Rapid-eye-movement sleep (REMS) or paradoxical sleep is associated with intense neuronal activity, fluctuations in autonomic control, body paralysis and brain-wide hyperemia. The mechanisms and functions of these energy-demanding patterns remain elusive and a global picture of brain activation during REMS is currently missing. In the present work, we performed functional ultrasound imaging on rats over multiple coronal and sagittal brain sections during hundreds of spontaneous REMS episodes to provide the spatiotemporal dynamics of vascular activity in 259 brain regions spanning more than 2/3 of the total brain volume. We first demonstrate a dissociation between basal/midbrain and cortical structures, the first ones sustaining tonic activation during REMS while the others are activated in phasic bouts. Second, we isolated the vascular compartment in our recordings and identified arteries in the anterior part of the brain as strongly involved in the blood supply during REMS episodes. Finally, we report a peculiar activation pattern in the posterior amygdala, which is strikingly disconnected from the rest of the brain during most REMS episodes. This last finding suggests that the amygdala undergoes specific processing during REMS and may be linked to the regulation of emotions and the creation of dream content during this very state.

The influence of sleep on fear extinction in trauma-related disorders

In Posttraumatic Stress Disorder (PTSD), fear and anxiety become dysregulated following psychologically traumatic events. Regulation of fear and anxiety involves both high-level cognitive processes such as cognitive reattribution and low-level, partially automatic memory processes such as fear extinction, safety learning and habituation. These latter processes are believed to be deficient in PTSD. While insomnia and nightmares are characteristic symptoms of existing PTSD, abundant recent evidence suggests that sleep disruption prior to and acute sleep disturbance following traumatic events both can predispose an individual to develop PTSD. Sleep promotes consolidation in multiple memory systems and is believed to also do so for low-level emotion-regulatory memory processes. Consequently sleep disruption may contribute to the etiology of PTSD by interfering with consolidation in low-level emotion-regulatory memory systems. During the first weeks following a traumatic event, when in the course of everyday life resilient individuals begin to acquire and consolidate these low-level emotion-regulatory memories, those who will develop PTSD symptoms may fail to do so. This deficit may, in part, result from alterations of sleep that interfere with their consolidation, such as REM fragmentation, that have also been found to presage later PTSD symptoms. Here, sleep disruption in PTSD as well as fear extinction, safety learning and habituation and their known alterations in PTSD are first briefly reviewed. Then neural processes that occur during the early post-trauma period that might impede low-level emotion regulatory processes through alterations of sleep quality and physiology will be considered. Lastly, recent neuroimaging evidence from a fear conditioning and extinction paradigm in patient groups and their controls will be considered along with one possible neural process that may contribute to a vulnerability to PTSD following trauma.

Posttraumatic stress disorder (PTSD), sleep, and cardiovascular disease risk: A mechanism-focused narrative review

OBJECTIVE

Growing longitudinal research has demonstrated that posttraumatic stress disorder (PTSD) precedes and predicts the onset of cardiovascular disease (CVD), and a number of physiological (e.g., dysregulation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, chronic systemic inflammation) and behavioral (e.g., physical inactivity, smoking, poor diet) factors might underlie this association. In this narrative review, we focus on sleep as a modifiable risk factor linking PTSD with CVD.

METHOD

We summarize the evidence for sleep disturbance after trauma exposure and the potential cardiotoxic effects of poor sleep, with an emphasis on mechanisms. In addition, we review the literature that has examined sleep in the context of the PTSD-CVD risk relation.

RESULTS

Although sleep disturbance is a hallmark symptom of PTSD and a well-established risk factor for the development of CVD, the role of sleep in the association between PTSD and CVD has been largely unexamined in the extant literature. However, such work has the potential to improve our understanding of mechanisms of risk and inform intervention efforts to offset elevated CVD risk after trauma.

CONCLUSIONS

We outline several recommendations for future research and behavioral medicine models in order to help define and address the role of sleep behavior in the development of CVD among trauma-exposed individuals with PTSD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

How Are the Sleep Problems of Children in the US Foster Care System Addressed?

OBJECTIVE

Evidence of poor sleep health among children in foster care continues to mount, but information about whether and how sleep problems are addressed is unavailable. The goal of this study was to begin to fill these significant knowledge gaps.

METHODS

Four hundred eighty-five foster caregivers from across the United States completed a survey focused on the sleep health of one child, 4 to 11 years ( M = 6.4; SD = 2.2) currently in their care. Caregivers provided quantitative and qualitative responses to questions regarding training, information, and services received in relation to their child's sleep. Caregivers also reported on the factors and strategies they perceived as most important for helping children in their care sleep well.

RESULTS

Only 13% of caregivers reported receiving any information/education about sleep from agencies or case workers, whereas 55% had sought help from a health provider related to their child's sleep. Nearly half of all caregivers (46%) reported giving their child melatonin. Caregivers reported that a bedtime routine/consistency, reassurance of safety/love, and a calming environment were most important for helping their child sleep well. A recurrent theme in qualitative responses was a need to mitigate child fear/anxiety at night.

CONCLUSION

Children in foster care face a range of risk factors that increase the likelihood of poor/insufficient sleep, but these findings suggest this critical aspect of health requires greater clinical and research attention. As these data were collected during the initial months of the COVID-19 pandemic, replication studies are necessary.

Boosting psychological change: Combining non-invasive brain stimulation with psychotherapy

Mental health disorders and substance use disorders are a leading cause of morbidity and mortality worldwide, and one of the most important challenges for public health systems. While evidence-based psychotherapy is generally pursued to address mental health challenges, psychological change is often hampered by non-adherence to treatments, relapses, and practical barriers (e.g., time, cost). In recent decades, Non-invasive brain stimulation (NIBS) techniques have emerged as promising tools to directly target dysfunctional neural circuitry and promote long-lasting plastic changes. While the therapeutic efficacy of NIBS protocols for mental illnesses has been established, neuromodulatory interventions might also be employed to support the processes activated by psychotherapy. Indeed, combining psychotherapy with NIBS might help tailor the treatment to the patient's unique characteristics and therapeutic goal, and would allow more direct control of the neuronal changes induced by therapy. Herein, we overview emerging evidence on the use of NIBS to enhance the psychotherapeutic effect, while highlighting the next steps in advancing clinical and research methods toward personalized intervention approaches.

Sleep spindle dynamics suggest over-consolidation in post-traumatic stress disorder

Devastating and persisting traumatic memories are a central symptom of post-traumatic stress disorder (PTSD). Sleep problems are highly co-occurrent with PTSD and intertwined with its etiology. Notably, sleep hosts memory consolidation processes, supported by sleep spindles (11–16 Hz). Here we assess the hypothesis that intrusive memory symptoms in PTSD may arise from excessive memory consolidation, reflected in exaggerated spindling. We use a newly developed spindle detection method, entailing minimal assumptions regarding spindle phenotype, to assess spindle activity in PTSD patients and traumatized controls. Our results show increased spindle activity in PTSD, which positively correlates with daytime intrusive memory symptoms. Together, these findings provide a putative mechanism through which the profound sleep disturbance in PTSD may contribute to memory problems. Due to its uniform and unbiased approach, the new, minimal assumption spindle analysis seems a promising tool to detect aberrant spindling in psychiatric disorders.

Heterogeneity in patterns of posttraumatic stress disorder symptoms and sleep disturbances among firefighters: Latent profile analyses

Firefighters are at increased risk for posttraumatic stress disorder (PTSD) symptoms and sleep disturbances due to occupational trauma exposure as well as the nature of their job (e.g., shift work, workplace stress). PTSD symptoms co-occur with sleep disturbances, including poor sleep quality, short sleep duration, and low sleep efficiency. No published studies have examined subgroups of firefighters based on PTSD symptoms and sleep disturbances. Thus, we used latent profile analysis to identify the best-fitting class solution to categorize firefighters based on endorsed PTSD symptoms and sleep disturbances and examined relations between the optimal class solution and health covariates (i.e., anger reactions, depression symptoms, emotion regulation difficulties, number of traumatic event types). The sample included 815 trauma-exposed firefighters (M_age = 38.63; 93.20% male). Results indicated three latent subgroups: High PTSD-Sleep Disturbances, Moderate PTSD-Sleep Disturbances, and Low PTSD-Sleep Disturbances. Multinomial logistic regression indicated that endorsing greater anger reactions, depression symptoms, and emotion regulation difficulties increased the chances of being in the more severe classes. Endorsing greater number of traumatic event types increased the chances of being in the Moderate vs. Low PTSD-Sleep Disturbances Classes. Findings improve our understanding of subgroups of firefighters based on PTSD and sleep disturbances and underscore the importance of addressing depression symptoms, anger management, and emotion regulation skills for firefighters reporting more severe PTSD symptoms and sleep disturbances.

Controllable and Uncontrollable Stress Differentially Impact Fear Conditioned Alterations in Sleep and Neuroimmune Signaling in Mice

Stress induces neuroinflammation and disrupts sleep, which together can promote a number of stress-related disorders. Fear memories associated with stress can resurface and reproduce symptoms. Our previous studies have demonstrated sleep outcomes can be modified by stressor controllability following stress and fear memory recall. However, it is unknown how stressor controllability alters neuroinflammatory signaling and its association with sleep following fear memory recall. Mice were implanted with telemetry transmitters and experienced escapable or inescapable footshock and then were re-exposed to the shuttlebox context one week later. Gene expression was assessed with Nanostring^® panels using RNA extracted from the basolateral amygdala and hippocampus. Freezing and temperature were examined as behavioral measures of fear. Increased sleep after escapable stress was associated with a down-regulation in neuro-inflammatory and neuro-degenerative related genes, while decreased sleep after inescapable stress was associated with an up-regulation in these genes. Behavioral measures of fear were virtually identical. Sleep and neuroimmune responses appear to be integrated during fear conditioning and reproduced by fear memory recall. The established roles of disrupted sleep and neuroinflammation in stress-related disorders indicate that these differences may serve as informative indices of how fear memory can lead to psychopathology.

Sleep as a window to target traumatic memories

Post-traumatic stress disorder (PTSD) is a severe psychiatric disorder in which traumatic memories result in flashbacks and nightmares. With one-third of patients not responding to standard exposure-based psychotherapy, new treatment strategies are needed. Sleep offers a unique time window to enhance therapeutic efficacy. Traumatic memories that are neutralized in therapy need to be stored back into memory (consolidated) during sleep to solidify the treatment effect. New basic research shows that memory consolidation can be enhanced by presenting sounds or scents that were linked to the memory at encoding, again during sleep. This procedure, termed targeted memory reactivation (TMR), has, despite its clinical potential, not been tested in (PTSD) patients. In this narrative review, we explore the potential of TMR as a new sleep-based treatment for PTSD. First we provide the necessary background on the memory and sleep principles underlying PTSD as well as the present applications and conditional factors of TMR. Then, we will discuss the outstanding questions and most promising experimental avenues when testing TMR to treat traumatic memories.

Is paradoxical sleep setting up innate and acquired complex sensorimotor and adaptive behaviours?: A proposed function based on literature review

We summarize here the progress in identifying the neuronal network as well as the function of paradoxical sleep and the gaps of knowledge that should be filled in priority. The core system generating paradoxical sleep localized in the brainstem is now well identified, and the next step is to clarify the role of the forebrain in particular that of the hypothalamus including the melanin-concentrating hormone neurons and of the basolateral amygdala. We discuss these two options, and also the discovery that cortical activation during paradoxical sleep is restricted to a few limbic cortices activated by the lateral supramammillary nucleus and the claustrum. Such activation nicely supports the findings recently obtained showing that neuronal reactivation occurs during paradoxical sleep in these structures, and induces both memory consolidation of important memory and forgetting of less relevant ones. The question that still remains to be answered is whether paradoxical sleep is playing more crucial roles in processing emotional and procedural than other types of memories. One attractive hypothesis is that paradoxical sleep is responsible for erasing negative emotional memories, and that this function is not properly functioning in depressed patients. On the other hand, the presence of a muscle atonia during paradoxical sleep is in favour of a role in procedural memory as new types of motor behaviours can be tried without harm during the state. In a way, it also fits with the proposed role of paradoxical sleep in setting up the sensorimotor system during development.

Paradoxical somatodendritic decoupling supports cortical plasticity during REM sleep

Rapid eye movement (REM) sleep is associated with the consolidation of emotional memories. Yet, the underlying neocortical circuits and synaptic mechanisms remain unclear. We found that REM sleep is associated with a somatodendritic decoupling in pyramidal neurons of the prefrontal cortex. This decoupling reflects a shift of inhibitory balance between parvalbumin neuron-mediated somatic inhibition and vasoactive intestinal peptide-mediated dendritic disinhibition, mostly driven by neurons from the central medial thalamus. REM-specific optogenetic suppression of dendritic activity led to a loss of danger-versus-safety discrimination during associative learning and a lack of synaptic plasticity, whereas optogenetic release of somatic inhibition resulted in enhanced discrimination and synaptic potentiation. Somatodendritic decoupling during REM sleep promotes opposite synaptic plasticity mechanisms that optimize emotional responses to future behavioral stressors.

Is PTSD an Evolutionary Survival Adaptation Initiated by Unrestrained Cytokine Signaling and Maintained by Epigenetic Change?

INTRODUCTION

Treatment outcomes for PTSD with current psychological therapies are poor, with very few patients achieving sustained symptom remission. A number of authors have identified physiological and immune disturbances in Post Traumatic Stress Disorder (PTSD) patients, but there is no unifying hypothesis that explains the myriad features of the disorder.

MATERIALS AND METHODS

The medical literature was reviewed over a 6-year period primarily using the medical database PUBMED.

RESULTS

The literature contains numerous papers that have identified a range of physiological and immune dysfunction in association with PTSD. This paper proposes that unrestrained cytokine signaling induces epigenetic changes that promote an evolutionary survival adaptation, which maintains a defensive PTSD phenotype. The brain can associate immune signaling with past threat and initiate a defensive behavioral response. The sympathetic nervous system is pro-inflammatory, while the parasympathetic nervous system is anti-inflammatory. Prolonged cholinergic withdrawal will promote a chronic inflammatory state. The innate immune cytokine IL-1β has pleiotropic properties and can regulate autonomic, glucocorticoid, and glutamate receptor functions, sleep, memory, and epigenetic enzymes. Changes in epigenetic enzyme activity can potentially alter phenotype and induce an adaptation. Levels of IL-1β correlate with severity and duration of PTSD and PTSD can be prevented by bolus administration of hydrocortisone in acute sepsis, consistent with unrestrained inflammation being a risk factor for PTSD. The nervous and immune systems engage in crosstalk, governed by common receptors. The benefits of currently used psychiatric medication may arise from immune, as well as synaptic, modulation. The psychedelic drugs (3,4-Methylenedioxymethamphetamine (MDMA), psilocybin, and ketamine) have potent immunosuppressive and anti-inflammatory effects on the adaptive immune system, which may contribute to their reported benefit in PTSD. There may be distinct PTSD phenotypes induced by innate and adaptive cytokine signaling.

CONCLUSION

In order for an organism to survive, it must adapt to its environment. Cytokines signal danger to the brain and can induce epigenetic changes that result in a persistent defensive phenotype. PTSD may be the price individuals pay for the genomic flexibility that promotes adaptation and survival.

Brief behavioral treatment for insomnia decreases trauma-related nightmare frequency in veterans

STUDY OBJECTIVES

Trauma-related nightmares are highly prevalent among veterans and are associated with higher severity insomnia and PTSD. Cognitive behavioral therapy for insomnia (CBT-I, typically 6-8 sessions) has been shown to reduce trauma-related nightmares. Brief behavioral treatment for insomnia (BBTI, 4 sessions) has been found to be comparable to CBT-I in decreasing insomnia severity; however, the effects of BBTI on nightmares have not been investigated. The current study tested the effects of BBTI on both trauma-related nightmares and non-trauma-related bad dreams using an active control group, progressive muscle relaxation therapy (PMRT). Additionally, we tested whether baseline trauma-related nightmare frequency and baseline non-trauma-related bad dream frequency moderated changes in insomnia severity.

METHODS

Participants were 91 military veterans with insomnia disorder randomized to BBTI or PMRT. Participants reported insomnia severity on the Insomnia Severity Index and reported trauma-related nightmare frequency and non-trauma-related bad dream frequency on the Pittsburgh Sleep Quality Index--PTSD Addendum.

RESULTS

We found that BBTI significantly reduced trauma-related nightmares from baseline to post-treatment while PMRT did not. However, reductions in trauma-related nightmares were not maintained at six month follow up. Neither BBTI nor PMRT reduced non-trauma-related bad dreams from baseline to post-treatment. We also found that neither baseline trauma-related nightmare frequency nor baseline non-trauma-related bad dream frequency moderated changes in insomnia symptom severity.

CONCLUSIONS

Findings from the current study suggest that BBTI may help to reduce trauma-related nightmares. Further research is needed to better understand potential mechanisms underlying how improved sleep may reduce trauma-related nightmares.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Brief Behavioral Insomnia Treatment Study (BBTI); Identifier: NCT02571452; URL: https://clinicaltrials.gov/ct2/show/NCT02571452.

A Narrative Review of the Association between Post-Traumatic Stress Disorder and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) and post-traumatic stress disorder (PTSD) are often co-morbid with implications for disease severity and treatment outcomes. OSA prevalence is higher in PTSD sufferers than in the general population, with a likely bidirectional effect of the two illnesses. There is substantial evidence to support the role that disturbed sleep may play in the pathophysiology of PTSD. Sleep disturbance associated with OSA may interfere with normal rapid eye movement (REM) functioning and thus worsen nightmares and sleep-related movements. Conversely, hyperarousal and hypervigilance symptoms of PTSD may lower the arousal threshold and thus increase the frequency of sleep fragmentation related to obstructive events. Treating OSA not only improves OSA symptoms, but also nightmares and daytime symptoms of PTSD. Evidence suggests that positive airway pressure (PAP) therapy reduces PTSD symptoms in a dose-dependent fashion, but also presents challenges to tolerance in the PTSD population. Alternative OSA treatments may be better tolerated and effective for improving both OSA and PTSD. Further research avenues will be introduced as we seek a better understanding of this complex relationship.

Targeted Memory Reactivation During REM Sleep in Patients With Social Anxiety Disorder

BACKGROUND

Social anxiety disorder (SAD) is characterized by a significant amount of fear when confronted to social situations. Exposure therapy, which is based on fear extinction, does not often lead to full remission. Here, based on evidence showing that rapid eye movement (REM) sleep promotes the consolidation of extinction memory, we used targeted memory reactivation (TMR) during REM sleep to enhance extinction learning in SAD.

METHODS

Forty-eight subjects with SAD were randomly assigned to two groups: control or TMR group. All patients had two successive exposure therapy sessions in a virtual reality (VR) environment, where they were asked to give a public talk in front of a virtual jury. At the end of each session, and only in the TMR group (N = 24), a sound was paired to the positive feedback phase of therapy (i.e., approval of their performance), which represented the memory to be strengthened during REM sleep. All participants slept at home with a wearable headband device which automatically identified sleep stages and administered the sound during REM sleep. Participants' anxiety level was assessed using measures of parasympathetic (root mean square of successive differences between normal heartbeats, RMSSD) and sympathetic (non-specific skin conductance responses, ns-SCRs) activity, and subjective measures (Subjective Units of Distress Scale, SUDS), during the preparation phase of their talks before (T1) and after (T2) one full-night's sleep and after 1 week at home (T3). Participants also filled in a dream diary.

RESULTS

We observed an effect of time on subjective measures of anxiety (SUDS). We did not find any difference in the anxiety levels of the two groups after 1 week of TMR at home. Importantly, the longer the total duration of REM sleep and the more stimulations the TMR group had at home, the less anxious (increased RMSSD) these participants were. Finally, fear in dreams correlated positively with ns-SCRs and SUDS at T3 in the TMR group.

CONCLUSION

TMR during REM sleep did not significantly modulate the beneficial effect of therapy on subjective anxiety. Yet, our results support that REM sleep can contribute to extinction processes and substantiate strong links between emotions in dreams and waking stress levels in these patients.

Prefrontal cortex, amygdala, and threat processing: implications for PTSD

Posttraumatic stress disorder can be viewed as a disorder of fear dysregulation. An abundance of research suggests that the prefrontal cortex is central to fear processing-that is, how fears are acquired and strategies to regulate or diminish fear responses. The current review covers foundational research on threat or fear acquisition and extinction in nonhuman animals, healthy humans, and patients with posttraumatic stress disorder, through the lens of the involvement of the prefrontal cortex in these processes. Research harnessing advances in technology to further probe the role of the prefrontal cortex in these processes, such as the use of optogenetics in rodents and brain stimulation in humans, will be highlighted, as well other fear regulation approaches that are relevant to the treatment of posttraumatic stress disorder and involve the prefrontal cortex, namely cognitive regulation and avoidance/active coping. Despite the large body of translational research, many questions remain unanswered and posttraumatic stress disorder remains difficult to treat. We conclude by outlining future research directions related to the role of the prefrontal cortex in fear processing and implications for the treatment of posttraumatic stress disorder.

Self-Conscious Affect Is Modulated by Rapid Eye Movement Sleep but Not by Targeted Memory Reactivation-A Pilot Study

The neurophysiological properties of rapid eye movement sleep (REMS) are believed to tune down stressor-related emotional responses. While prior experimental findings are controversial, evidence suggests that affective habituation is hindered if REMS is fragmented. To elucidate the topic, we evoked self-conscious negative affect in the participants (N = 32) by exposing them to their own out-of-tune singing in the evening. Affective response to the stressor was measured with skin conductance response and subjectively reported embarrassment. To address possible inter-individual variance toward the stressor, we measured the shame-proneness of participants with an established questionnaire. The stressor was paired with a sound cue to pilot a targeted memory reactivation (TMR) protocol during the subsequent night's sleep. The sample was divided into three conditions: control (no TMR), TMR during slow-wave sleep, and TMR during REMS. We found that pre- to post-sleep change in affective response was not influenced by TMR. However, REMS percentage was associated negatively with overnight skin conductance response habituation, especially in those individuals whose REMS was fragmented. Moreover, shame-proneness interacted with REM fragmentation such that the higher the shame-proneness, the more the affective habituation was dependent on non-fragmented REMS. In summary, the potential of REMS in affective processing may depend on the quality of REMS as well as on individual vulnerability toward the stressor type.

Hypocretin in locus coeruleus and dorsal raphe nucleus mediates inescapable footshock stimulation (IFS)-induced REM sleep alteration

Hypocretin (hcrt) is a stress-reacting neuropeptide mediating arousal and energy homeostasis. An inescapable footshock stimulation (IFS) could initiate the hcrt release from the lateral hypothalamus (LHA) and suppresses rapid eye movement (REM) sleep in rodents. However, the effects of the IFS-induced hcrts on REM-off nuclei, the locus coeruleus (LC) and dorsal raphe nucleus (DRN), remained unclear. We hypothesized that the hcrt projections from the LHA to LC or DRN mediate IFS-induced sleep disruption. Our results demonstrated that the IFS increased hcrt expression and the neuronal activities in the LHA, hypothalamus, brainstem, thalamus, and amygdala. Suppressions of REM sleep and slow wave activity during non-REM (NREM) sleep caused by the high expression of hcrts were blocked when a non-specific and dual hcrt receptor antagonist was administered into the LC or DRN. Furthermore, the IFS also caused an elevated innate anxiety, but was limitedly influenced by the hcrt antagonist. This result suggests that the increased hcrt concentrations in the LC and DRN mediate stress-induced sleep disruptions and might partially involve IFS-induced anxiety.