Sleep disturbances in the aftermath of trauma and posttraumatic stress disorder

Sleep disturbances, including nightmares and insomnia, are prominent following trauma and with posttraumatic stress disorder (PTSD) and likely contribute to the pathogenesis of the disorder. Findings from laboratory studies of PTSD have been inconsistent in terms of documenting objective impaired sleep maintenance but have been somewhat more consistent in indicating alterations of rapid eye movement (REM) sleep. Studies of the early aftermath of trauma can reduce the complexity associated with chronicity and comorbidity, and may have implications for early diagnosis and prevention. Multiple studies indicate that dream content is affected by recent threatening experiences. The development of PTSD is associated with a more replicative type of nightmare content. Sleep is reported to be generally disrupted following trauma especially among those developing PTSD. The limited number of studies that provide objective recorded indices during the early aftermath of trauma also provide a mixed picture regarding overall sleep maintenance. Recent data suggest that a more specific disruption of REM sleep may be associated with the development of PTSD and that this disruption is associated with an increased signal of sympathetic nervous system activation during REM sleep. Disrupted REM sleep and increased sympathetic/noradrenergic activity may have implications for understanding recent promising interventions for PTSD sleep disturbance that can be applied to early intervention.     

Subjective Sleep Disturbances in Sexual Assault Survivors: Associations With Trauma and Posttraumatic Stress Disorder Symptom Severity

Prior work implicates sleep disturbance in the development and maintenance of posttraumatic stress disorder (PTSD). However, the majority of this literature has focused on combat veteran men, and limited work has examined links between sleep disturbance and PTSD symptoms in sexual assault survivors. This is a notable gap in the literature, as sexual trauma is disproportionately likely to result in PTSD and is more common in women. We sought to examine the relations between subjective sleep disturbance, sexual assault severity, and PTSD symptoms in a sample of sexual assault survivors with PTSD (PTSD+), without PTSD (PTSD-), and healthy controls. The sample (N = 60) completed the Insomnia Severity Index and prospectively monitored their sleep for 1 week using the Consensus Sleep Diary. The sexual assault survivors also completed the Sexual Experiences Survey and PTSD Checklist-5. Results of group comparisons found that the PTSD+ group reported significantly higher insomnia symptoms, longer sleep onset latency, more nocturnal awakenings, and lower sleep quality compared to the healthy control group and higher insomnia symptoms compared to the PTSD- group. Results of regression analyses in the sexual assault survivors found that insomnia symptoms and number of nocturnal awakenings were significantly associated with higher PTSD symptoms, and sexual assault severity was significantly associated with higher insomnia symptoms, longer sleep onset latency, and lower sleep quality. These findings highlight specific features of sleep disturbance that are linked to trauma and PTSD symptom severity among sexual assault survivors.     

睡眠对恐惧学习的影响及其认知神经机制

睡眠问题可能会诱发恐惧相关情绪障碍(焦虑、创伤性应激障碍、恐怖症等),研究睡眠影响恐惧学习的认知神经机制,有助于增强对恐惧相关情绪障碍的预测、诊断和治疗。以往研究表明睡眠剥夺影响恐惧习得和消退主要是通过抑制vmPFC活动,阻碍其与杏仁核的功能连接,从而导致恐惧习得增强或是消退学习受损。进一步研究发现睡眠不同阶段对恐惧学习相关脑区有独特的影响:剥夺(缺乏)快速眼动睡眠会抑制vmPFC活动、增强杏仁核、海马激活,导致恐惧习得增强,消退学习受损,此外边缘皮层的功能连接减少破坏了记忆巩固(恐惧记忆和消退记忆);而慢波睡眠主要与海马变化有关,慢波睡眠期间进行目标记忆重激活可促进恐惧消退学习。未来研究需要增加睡眠影响恐惧泛化的神经机制研究、及昼夜节律中断对恐惧消退的影响,以及关注动物睡眠研究向人类睡眠研究转化中存在的问题。     

Dreaming and the brain: toward a cognitive neuroscience of conscious states

Sleep researchers in different disciplines disagree about how fully dreaming can be explained in terms of brain physiology. Debate has focused on whether REM sleep dreaming is qualitatively different from nonREM (NREM) sleep and waking. A review of psychophysiological studies shows clear quantitative differences between REM and NREM mentation and between REM and waking mentation. Recent neuroimaging and neurophysiological studies also differentiate REM, NREM, and waking in features with phenomenological implications. Both evidence and theory suggest that there are isomorphisms between the phenomenology and the physiology of dreams. We present a three-dimensional model with specific examples from normally and abnormally changing conscious states.     

Change in sleep symptoms across Cognitive Processing Therapy and Prolonged Exposure: A longitudinal perspective

Sleep disturbance is a core component in posttraumatic stress disorder (PTSD). Although cognitive-behavioral treatments for PTSD reduce the severity of sleep symptoms, they do not lead to complete remission. The present study examines the impact of Cognitive Processing Therapy (CPT) and Prolonged Exposure (PE) on subjective measures of sleep disturbance from treatment randomization through long-term follow-up (LTFU). Participants were 171 female rape victims with PTSD who were randomly assigned to CPT, PE, or Minimal Attention (MA). After 6-weeks, the MA group was randomized to CPT or PE. Sleep symptoms were assessed at baseline, post-MA, post-treatment, 3-months, 9-months and LTFU using the Pittsburgh Sleep Quality Index (PSQI) and nightmare and insomnia items from the Clinician Administered PTSD Scale. Change in sleep during MA, from pre- to post-treatment for CPT and PE, and from post-treatment through LTFU was assessed using piecewise hierarchical linear modeling with the intent-to-treat sample. Controlling for medication, sleep improved during CPT and PE compared to MA, and treatment gains were maintained through LTFU. CPT and PE were equally efficacious and improvements persist over LTFU, yet, neither produced remission of sleep disturbance. Overall, sleep symptoms do not remit and may warrant sleep-specific treatments.     

Sleep Disturbances Among Combat Military Veterans: A Comparative Study Using Subjective and Objective Sleep Assessments

The sleep characteristics of 37 military veterans and active-duty service members (17 with PTSD and 20 without PTSD) of recent wars were analyzed to determine if combat deployment, with its associated sleep restriction, may be an alternative explanation for the sleep complaints found among combat veterans with PTSD (as determined by PTSD Checklist Military Version scores). Over a 1-week period, sleep data were collected using sleep actigraphy and self-report. Across the entire sample, subjective and objective assessment methods of sleep were strongly correlated, although there were some notable within-group differences. Specifically, although sleep duration between groups did not differ based on actigraphy, veterans without PTSD reported sleeping 1 h and 11 min (p = .002) longer than did veterans with PTSD. In an effort to determine why individuals without PTSD might be overreporting sleep, we found that symptoms of emotional arousal (anger, anxiety, and nightmares) were significantly correlated with self-reported sleep duration, suggesting a pattern of higher autonomic arousal found in veterans with PTSD. Thus, although sleeping for 6 h, the higher levels of emotional arousal reported by veterans with PTSD may mean that they do not perceive their sleep as restful. Further research is necessary to determine if the sleep architecture of veterans with PTSD is actually different from that of combat veterans without PTSD and if such differences are actually amenable to standard behavioral treatments for this disorder.     

The case against memory consolidation in REM sleep

We present evidence disputing the hypothesis that memories are processed or consolidated in REM sleep. A review of REM deprivation (REMD) studies in animals shows these reports to be about equally divided in showing that REMD does, or does not, disrupt learning/memory. The studies supporting a relationship between REM sleep and memory have been strongly criticized for the confounding effects of very stressful REM deprivation techniques. The three major classes of antidepressant drugs, monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), and selective serotonin reuptake inhibitors (SSRIs), profoundly suppress REM sleep. The MAOIs virtually abolish REM sleep, and the TCAs and SSRIs have been shown to produce immediate (40-85%) and sustained (30-50%) reductions in REM sleep. Despite marked suppression of REM sleep, these classes of antidepressants on the whole do not disrupt learning/memory. There have been a few reports of patients who have survived bilateral lesions of the pons with few lingering complications. Although these lesions essentially abolished REM sleep, the patients reportedly led normal lives. Recent functional imaging studies in humans have revealed patterns of brain activity in REM sleep that are consistent with dream processes but not with memory consolidation. We propose that the primary function of REM sleep is to provide periodic endogenous stimulation to the brain which serves to maintain requisite levels of central nervous system (CNS) activity throughout sleep. REM is the mechanism used by the brain to promote recovery from sleep. We believe that the cumulative evidence indicates that REM sleep serves no role in the processing or consolidation of memory.     

Posttraining increases in REM sleep intensity implicate REM sleep in memory processing and provide a biological marker of learning potential

Posttraining rapid eye movement (REM) sleep has been reported to be important for efficient memory consolidation. The present results demonstrate increases in the intensity of REM sleep during the night of sleep following cognitive procedural/implicit task acquisition. These REM increases manifest as increases in total number of rapid eye movements (REMs) and REM densities, whereas the actual time spent in REM sleep did not change. Further, the participants with the higher intelligence (IQ) scores showed superior task acquisition scores as well as larger posttraining increases in number of REMs and REM density. No other sleep state changes were observed. None of the pretraining baseline measures of REM sleep were correlated with either measured IQ or task performance. Posttraining increases in REM sleep intensity implicate REM sleep mechanisms in further off-line memory processing, and provide a biological marker of learning potential.     

An assessment of sleep architecture as a function of degree of handedness in college women using a home sleep monitor

The present study examined sleep architecture as a function of handedness in a population of undergraduate college women using a home sleep monitor. Compared to strongly handed individuals, participants with a tendency toward mixed-handedness had a shorter sleep latency and spent a greater percentage of their sleep period asleep and less awake. Increasing mixed-handedness was also associated with increased NREM; strong-handedness was associated with increased REM. Results are placed in a neurophysiological framework wherein corpus callosum mediated differences in interhemispheric interaction during Wake, REM, and NREM on the one hand, and individual differences in corpus callosum morphology and hemispheric communication as a function of handedness on the other, interact to result in handedness differences in sleep architecture.     

Electroencephalographic and autonomic alterations in subjects with frequent nightmares during pre-and post-REM periods

Abnormal arousal processes, sympathetic influences, as well as wake-like alpha activity during sleep were reported as pathophysiological features of Nightmare Disorder. We hypothesized that in Nightmare Disorder, wake-like cortical activity and peripheral measures linked to arousals would be triggered by physiological processes related to the initiation of REM periods. Therefore, we examined electroencephalographic (EEG), motor and autonomous (cardiac) activity in a group of nightmare (NM) and healthy control (CTL) subjects during sleep-state-transitions while controlling for the confounding effects of trait anxiety. Based on the second-nights’ polysomnographic recordings of 19 Nightmare Disordered (NM) and 21 control (CTL) subjects, we examined the absolute power spectra focusing on the alpha range, measures of heart rate variability (HRV) and motor (muscle tone) activity during pre-REM and post-REM periods, separately. According to our results, the NM group exhibited increased alpha power during pre-REM, but not in post-REM, or stable, non-transitory periods. While CTL subjects showed increased HRV during pre-REM periods in contrast to post-REM ones, NM subjects did not exhibit such sleep state-specific differences in HRV, but showed more stable values across the examined sleep stages and less overall variability reflecting generally attenuated parasympathetic activity during sleep-state-transitions and during stable, non-transitory NREM states. These differences were not mediated by waking levels of trait anxiety. Moreover, in both groups, significant differences emerged regarding cortical and motor (muscle tone) activity between pre-REM and post-REM conditions, reflecting the heterogeneity of NREM sleep. Our findings indicate that NM subjects’ sleep is compromised during NREM–REM transitions, but relatively stabilized after REM periods. The coexistence of sleep-like and wake-like cortical activity in NM subjects seems to be triggered by REM/WAKE promoting neural activity. We propose that increased arousal-related phenomena in NREM–REM transitions might reflect altered emotional processing in NM subjects.     

NonREM sleep mentation in chronically-treated persons with schizophrenia

This study examined the laboratory dream content reported by 14 patients with schizophrenia and 15 controls, with a focus on reports obtained from NonREM sleep. Both the controls' and patients' frequency of dream recall following awakenings from NonREM and REM sleep were similar to values reported for healthy participants. Patients' NonREM sleep narratives were shorter than those from controls. When compared to their reports from REM sleep, both groups' NonREM sleep reports included significantly fewer words and reportable items. The controls were more likely to report a subjective feeling of bizarreness for their REM sleep reports as compared to their NonREM sleep reports. This difference was not observed in patients with schizophrenia. Taken together, these findings suggest few differences between the NonREM sleep mentation of patients with schizophrenia and of controls and that sleep stage cognitive style is comparable in both groups, with NonREM sleep reports being more thought-like, less elaborate and bizarre than REM sleep reports.     

The role of sleep in changing our minds: a psychologist's discussion of papers on memory reactivation and consolidation in sleep

The group of papers on memory reactivation and consolidation during sleep included in this volume represents cutting edge work in both animals and humans. They support that the two types of sleep serve different necessary functions. The role of slow wave sleep (SWS) is reactivation of the hippocampal-neocortical circuits activated during a waking learning period, while REM sleep is responsible for the consolidation of this new learning into long-term memory. These studies provide further insights into mechanisms involved in brain plasticity. Robeiro has demonstrated the upregulation of an immediate-early gene (IEG zif 268) to waking levels, which occurs only in REM and only in connection with new learning. McNaughton and his group have identified electrical indicators that the hippocampus and neocortex are talking to each other by testing the coactivation of hippocampal sharp wave bursts in SWS and shifts from down to up states of activation in the neocortex. In human studies Smith's group reports work on individual differences such as intelligence and presleep alcohol that affect postsleep performance, and Stickgold and collaborators report that a short nap will improve performance if it contains REM sleep. Payne and Nadel suggest that the recall benefit associated with REM sleep may be due to its association with increased cortisol levels. These papers are important not only in their individual contributions but also in revitalizing the work coordinating waking and sleep. This promises to further the understanding of how our unique capacity to learn from experience and modify our behavior takes place.     

Gender and posttraumatic stress: sexual violence as an explanation for women's increased risk

Women are approximately twice as likely as men to develop posttraumatic stress disorder (PTSD), but the cause of this disparity remains unclear. This study evaluated 2 alternative explanations of gender differences in PTSD, one pointing to an intrinsic vulnerability in women and the other emphasizing sexual violence across the life span. To test these competing theories, the authors analyzed National Violence Against Women Survey data from 591 victims of partner aggression. Results suggested that gender, when considered alone, has a small but significant effect on PTSD symptom severity. However, once models factor in sexual victimization history, the latter replaces gender as a key determinant of PTSD symptoms. These findings argue against theories of "feminine vulnerability," instead linking PTSD risk to sexually violent situations.     

A review of mentation in REM and NREM sleep: "covert" REM sleep as a possible reconciliation of two opposing models

Numerous studies have replicated the finding of mentation in both rapid eye movement (REM) and nonrapid eye movement (NREM) sleep. However, two different theoretical models have been proposed to account for this finding: (1) a one-generator model, in which mentation is generated by a single set of processes regardless of physiological differences between REM and NREM sleep; and (2) a two-generator model, in which qualitatively different generators produce cognitive activity in the two states. First, research is reviewed demonstrating conclusively that mentation can occur in NREM sleep; global estimates show an average mentation recall rate of about 50% from NREM sleep--a value that has increased substantially over the years. Second, nine different types of research on REM and NREM cognitive activity are examined for evidence supporting or refuting the two models. The evidence largely, but not completely, favors the two-generator model. Finally, in a preliminary attempt to reconcile the two models, an alternative model is proposed that assumes the existence of covert REM sleep processes during NREM sleep. Such covert activity may be responsible for much of the dreamlike cognitive activity occurring in NREM sleep.     

Memory consolidation during sleep: interactive effects of sleep stages and HPA regulation

Sleep is critically involved in the consolidation of previously acquired memory traces. However, nocturnal sleep is not uniform but is subject to distinct changes in electrophysiological and neuroendocrine activity. Specifically, the first half of the night is dominated by slow wave sleep (SWS), whereas rapid eye movement (REM) sleep prevails in the second half. Concomitantly, hypothalamo-pituitary-adrenal (HPA) activity as indicated by cortisol release is suppressed to a minimum during early sleep, while drastically increasing during late sleep. We have shown that the different sleep stages and the concomitant glucocorticoid release are interactively involved in the consolidation of different types of memories. SWS-rich early sleep has been demonstrated to benefit mainly the consolidation of hippocampus-dependent declarative memories (i.e. facts and episodes). In contrast, REM sleep-rich late sleep was shown to improve in particular emotional memories involving amygdalar function, as well as procedural memories (for skills) not depending on hippocampal or amygdalar function. Enhancing plasma glucocorticoid concentrations during SWS-rich early sleep counteracted hippocampus-dependent declarative memory consolidation, but did not affect hippocampus-independent procedural memory. Preventing the increase in cortisol during late REM sleep-rich sleep by administration of metyrapone impaired hippocampus-dependent declarative memory but enhanced amygdala-dependent emotional aspects of memory. The data underscore the importance of pituitary-adrenal inhibition during early SWS-rich sleep for efficient consolidation of declarative memory. The increase in cortisol release during late REM sleep-rich sleep may counteract an overshooting consolidation of emotional memories.     

Spatial and reversal learning in the Morris water maze are largely resistant to six hours of REM sleep deprivation following training

This first test of the role of REM (rapid eye movement) sleep in reversal spatial learning is also the first attempt to replicate a much cited pair of papers reporting that REM sleep deprivation impairs the consolidation of initial spatial learning in the Morris water maze. We hypothesized that REM sleep deprivation following training would impair both hippocampus-dependent spatial learning and learning a new target location within a familiar environment: reversal learning. A 6-d protocol was divided into the initial spatial learning phase (3.5 d) immediately followed by the reversal phase (2.5 d). During the 6 h following four or 12 training trials/day of initial or reversal learning phases, REM sleep was eliminated and non-REM sleep left intact using the multiple inverted flowerpot method. Contrary to our hypotheses, REM sleep deprivation during four or 12 trials/day of initial spatial or reversal learning did not affect training performance. However, some probe trial measures indicated REM sleep-deprivation-associated impairment in initial spatial learning with four trials/day and enhancement of subsequent reversal learning. In naive animals, REM sleep deprivation during normal initial spatial learning was followed by a lack of preference for the subsequent reversal platform location during the probe. Our findings contradict reports that REM sleep is essential for spatial learning in the Morris water maze and newly reveal that short periods of REM sleep deprivation do not impair concurrent reversal learning. Effects on subsequent reversal learning are consistent with the idea that REM sleep serves the consolidation of incompletely learned items.     

Brain Gene Expression During REM Sleep Depends on Prior Waking Experience

In most mammalian species studied, two distinct and successive phases of sleep, slow wave (SW), and rapid eye movement (REM), can be recognized on the basis of their EEG profiles and associated behaviors. Both phases have been implicated in the offline sensorimotor processing of daytime events, but the molecular mechanisms remain elusive. We studied brain expression of the plasticity-associated immediate-early gene (IEG) zif-268 during SW and REM sleep in rats exposed to rich sensorimotor experience in the preceding waking period. Whereas nonexposed controls show generalized zif-268 down-regulation during SW and REM sleep, zif-268 is upregulated during REM sleep in the cerebral cortex and the hippocampus of exposed animals. We suggest that this phenomenon represents a window of increased neuronal plasticity during REM sleep that follows enriched waking experience.     

TRANSITION TO PARENTHOOD AND MENTAL HEALTH IN FIRST‐TIME PARENTS

This study aimed to examine the transition to parenthood and mental health in first‐time parents in detail and explore any differences in this transition in the context of parental gender and postpartum mental health. Semistructured clinical interviews (Birmingham Interview for Maternal Mental Health) were carried out with 46 women and 40 men, 5 months after birth. Parents were assessed on pre‐ and postpartum anxiety, depression, and postpartum posttraumatic stress disorder (PTSD), and a range of adjustment and relationship variables. One fourth of the men and women reported anxiety in pregnancy, reducing to 21% of women and 8% of men after birth. Pregnancy and postpartum depression rates were roughly equal, with 11% of women and 8% of men reporting depression. Postpartum PTSD was experienced by 5% of parents. Postpartum mental health problems were significantly associated with postpartum sleep deprivation (odds ratio [OR] = 7.5), complications in labor (OR = 5.1), lack of postpartum partner support (OR = 8.0), feelings of parental unworthiness (OR = 8.3), and anger toward the infant (OR = 4.4). Few gender differences were found for these variables. This study thus highlights the importance of focusing interventions on strengthening the couple's relationship and avoiding postnatal sleep deprivation, and to address parents’ feelings of parental unworthiness and feelings of anger toward their baby.     

From Posttrauma to Gender and Back: A Gender Motivation Theory-Explanation of Gender Differences in Trauma Exposure,Symptoms, Diagnosis,and Implications

This article proposes the “gender motivation theory” as a potential starting point for the study of gender differences in posttraumatic stress disorder (PTSD). Grounded in evolutionary and sociological theories, the gender motivational theory argues that men are generally motivated by status enhancement, whereas women are motivated by risk reduction. Accordingly, the theory considers these differing motivations as the core factor differentiating men and women in challenging situations regarding their perception, meaning, experience, and behavior. The theory refers to PTSD as a subjectively perceived failure fulfilling gender motives. Applying this theory to trauma victims enables expanding and increasing gender sensibility for an understanding of PTSD and its various consequences. It also allows a broader and deeper understanding of gender beyond normative boundaries. The article examines the validity of the gender motivation theory in view of the cumulative empirical evidence of gender differences in the study of PTSD as well as other fields of knowledge. Additionally, the proposed theory offers a coherent perspective and guidelines for further examination and practical applications in PTSD research.