Does acute TBI-related sleep disturbance predict subsequent neuropsychiatric disturbances?

Characteristics and neural mechanisms of sleep-wake disturbances after traumatic brain injury

Sleep-wake disturbances (SWDs) is one of the most common complaints following traumatic brain injury (TBI). The high prevalence and socioeconomic burden of sleep-wake disturbances (SWDs) post-TBI have only been recognized in the past decade. Common SWDs induced by TBI include excessive daytime sleepiness (EDS), hypersomnia, insomnia, obstructive sleep apnea (OSA), and circadian rhythm sleep disorders. Sleep disturbances can significantly compromise quality of life, strain interpersonal relationships, diminish work productivity, exacerbate other clinical conditions, and impede the rehabilitation process of TBI patients. Consequently, the prompt regulation and enhancement of sleep homeostasis in TBI patients is of paramount importance. Although studies have shown that abnormal neural network function, neuroendocrine changes, disturbance of sleep-wake regulators, and immune inflammatory responses related to brain structural damage induced by TBI are involved in the development of SWDs, the exact neuropathological mechanisms are still poorly understood. Thus, we systematically review the current clinical and experimental studies on the characteristics and possible neural mechanisms of post-TBI SWDs. Elucidating the neural underpinnings of post- TBI SWDs holds the potential to diversify and enhance therapeutic approaches for these conditions. Such advancements could hasten the recuperation of TBI patients and ameliorate their overall quality of life. It is our aspiration that departments specializing in neurosurgery, rehabilitation, and neuropsychiatry will be able to recognize and address these conditions promptly, thereby facilitating the healing journey of affected individuals.

Association between Sleep Disturbances at Subacute Stage of Mild Traumatic Brain Injury and Long-Term Outcomes

Mild (mTBI) traumatic brain injury (TBI) accounts for the majority of all TBI cases. Evidence has suggested that patients with mTBI can suffer from long-lasting cognitive deficits, persistent symptoms, and decreased quality of life. Sleep disorders are commonly observed after TBI, with the prevalence rate of sleep disturbances in persons with TBI being much higher than that in the general population. Poor sleep quality can impair cognitive functions in the general population. This effect of sleep disturbances may impede the recovery processes in the population with TBI. The objective of this study is to add to our understanding of the relationship between self-reported sleep problems and other post-concussion symptoms and look at the association between early sleep problems and long-term outcomes in mTBI. Post-concussion symptoms, neurocognitive functions, level of global outcomes, and rating of satisfaction of life were assessed in 64 patients with mTBI. The results revealed that the presence of sleep disturbances co-occur with an increased level of overall post-concussion symptoms at the subacute stage of mTBI, particularly with symptoms including poor concentration, memory problems, and irritability. In addition, sleep disturbance at the subacute stage is associated with persistent poor concentration and memory problems, as well as worse neurocognitive function, slower overall recovery, and lower satisfactory of life at the long term. Our findings suggest that sleep disturbance can be a prognostic factor of long-term outcomes after mTBI. Early interventions to improve sleep quality can have potential benefits to facilitate the recovery process from mTBI.

Dietary Supplementation With Branched Chain Amino Acids to Improve Sleep in Veterans With Traumatic Brain Injury: A Randomized Double-Blind Placebo-Controlled Pilot and Feasibility Trial

Study Objectives

Traumatic brain injury (TBI) is associated with chronic sleep disturbances and cognitive impairment. Our prior preclinical work demonstrated dietary supplementation with branched chain amino acids (BCAA: leucine, isoleucine, and valine), precursors to de novo glutamate production, restored impairments in glutamate, orexin/hypocretin neurons, sleep, and memory in rodent models of TBI. This pilot study assessed the feasibility and preliminary efficacy of dietary supplementation with BCAA on sleep and cognition in Veterans with TBI.

Methods

Thirty-two Veterans with TBI were prospectively enrolled in a randomized, double-blinded, placebo-controlled trial comparing BCAA (30 g, b.i.d. for 21-days) with one of two placebo arms (microcrystalline cellulose or rice protein, both 30 g, b.i.d. for 21-days). Pre- and post-intervention outcomes included sleep measures (questionnaires, daily sleep/study diaries, and wrist actigraphy), neuropsychological testing, and blood-based biomarkers related to BCAA consumption.

Results

Six subjects withdrew from the study (2/group), leaving 26 remaining subjects who were highly adherent to the protocol (BCAA, 93%; rice protein, 96%; microcrystalline, 95%; actigraphy 87%). BCAA were well-tolerated with few side effects and no adverse events. BCAA significantly improved subjective insomnia symptoms and objective sleep latency and wake after sleep onset on actigraphy.

Conclusion

Dietary supplementation with BCAA is a mechanism-based, promising intervention that shows feasibility, acceptability, and preliminary efficacy to treat insomnia and objective sleep disruption in Veterans with TBI. A larger scale randomized clinical trial is warranted to further evaluate the efficacy, dosing, and duration of BCAA effects on sleep and other related outcome measures in individuals with TBI.

Clinical Trial Registration

[http://clinicaltrials.gov/], identifier [NCT03990909].

The Bidirectional Link Between Sleep Disturbances and Traumatic Brain Injury Symptoms: A Role for Glymphatic Dysfunction?

Mild traumatic brain injury (mTBI), often referred to as concussion, is a major cause of morbidity and mortality worldwide. Sleep disturbances are common after mTBI. Moreover, subjects who develop subjective sleep complaints after mTBI also report more severe somatic, mental health, and cognitive impairment and take longer to recover from mTBI sequelae. Despite many previous studies addressing the role of sleep in post-mTBI morbidity, the mechanisms linking sleep to recovery after mTBI remain poorly understood. The glymphatic system is a brainwide network that supports fluid movement through the cerebral parenchyma and the clearance of interstitial solutes and wastes from the brain. Notably, the glymphatic system is active primarily during sleep. Clearance of cellular byproducts related to somatic, mental health, and neurodegenerative processes (e.g., amyloid-β and tau, among others) depends in part on intact glymphatic function, which becomes impaired after mTBI. In this viewpoint, we review the current knowledge regarding the association between sleep disturbances and post-mTBI symptoms. We also discuss the role of glymphatic dysfunction as a potential link between mTBI, sleep disruption, and posttraumatic morbidity. We outline a model where glymphatic dysfunction and sleep disruption caused by mTBI may have an additive effect on waste clearance, leading to cerebral dysfunction and impaired recovery. Finally, we review the novel techniques being developed to examine glymphatic function in humans and explore potential interventions to alter glymphatic exchange that may offer a novel therapeutic approach to those experiencing poor sleep and prolonged symptoms after mTBI.

The Impact of Opioid Medications on Sleep Architecture and Nocturnal Respiration During Acute Recovery From Moderate to Severe Traumatic Brain Injury: A TBI Model Systems Study

OBJECTIVES

To describe patient and clinical characteristics associated with receipt of opioid medications and identify differences in sleep quality, architecture, and sleep-related respiration between those receiving and not receiving opioid medications.

SETTING

Acute inpatient rehabilitation care for moderate to severe traumatic brain injury (TBI).

PARTICIPANTS

A total of 248 consecutive admissions for inpatient rehabilitation care following moderate to severe TBI (average age of 43.6 years), who underwent level 1 polysomnography (PSG) (average time since injury: 120 days) across 6 sites.

DESIGN

Cross-sectional, secondary analyses.

MAIN MEASURES

The PSG sleep parameters included total sleep time (TST), sleep efficiency (SE), wake after sleep onset, rapid eye movement (REM) latency, sleep staging, and arousal and awakening indices. Respiratory measures included oxygen saturation, central apnea events per hour, obstructive apnea and hypopnea events per hour, and total apnea-hypopnea index.

RESULTS

After adjustment for number of prescribed medication classes, those receiving opioid medications on the day of PSG experienced increased TST relative to those not receiving opioid medications (estimated mean difference [EMD] = 31.58; 95% confidence interval [CI], 1.9-61.3). Other indices of sleep did not differ significantly between groups. Among respiratory measures those receiving opioids on the day of PSG experienced increased frequency of central sleep apnea events during total (EMD = 2.92; 95% CI, 0.8-5.0) and non-REM sleep (EMD = 3.37; 95% CI, 1.0-5.7) and higher frequency of obstructive sleep apnea events during REM sleep (EMD = 6.97; 95% CI, 0.1-13.8). Compared with those who did not, receiving opioids was associated with lower oxygen saturation nadir during total sleep (EMD = -3.03; 95% CI, -5.6 to -0.4) and a greater number of oxygen desaturations across REM (EMD = 8.15; 95% CI, 0.2-16.1), non-REM (EMD = 7.30; 95% CI, 0.3-14.4), and total sleep (EMD = 8.01; 95% CI, 0.8-15.2) Greater total apnea-hypopnea index was observed during REM (EMD = 8.13; 95% CI, 0.8-15.5) and total sleep (EMD = 7.26; 95% CI, 0.08-14.4) for those receiving opioids.

CONCLUSION

Opioid use following moderate to severe TBI is associated with an increase in indicators of sleep-related breathing disorders, a modifiable condition that is prevalent following TBI. As sleep-wake disorders are associated with poorer rehabilitation outcomes and opioid medications may frequently be administered following traumatic injury, additional longitudinal investigations are warranted in determining whether a causal relation between opioids and sleep-disordered breathing in those following moderate to severe TBI exists. Given current study limitations, future studies can improve upon methodology through the inclusion of indication for and dosage of opioid medications in this population when examining these associations.

Baseline sleep quality moderates symptom improvement in veterans with comorbid PTSD and TBI receiving trauma-focused treatment

Poor sleep quality is common among Veterans with posttraumatic stress disorder (PTSD) and history of traumatic brain injury (TBI). However, the relationship between sleep quality and treatment outcomes following trauma-focused interventions is less well-understood in this population. We sought to better understand whether 1) sleep quality changed as a result of trauma-focused treatment and 2) if baseline sleep quality moderated psychological and neurobehavioral treatment outcomes. Our sample consisted of 100 Iraq/Afghanistan era Veterans with PTSD and history of mild to moderate TBI who were randomized to one of two trauma-focused treatments: 1) Cognitive Processing Therapy (CPT) or 2) combined CPT and Cognitive Symptom Management and Rehabilitation Therapy (SMART-CPT). Self-reported sleep quality, psychiatric symptoms (PTSD and depression), and neurobehavioral concerns were assessed at multiple timepoints throughout the study. Multilevel modeling showed sleep quality did not improve, regardless of treatment condition. However, worse baseline sleep quality was associated with less improvement in PTSD symptoms and cognitive complaints. There was no effect of baseline sleep quality on change in depression symptoms. These findings suggest that more targeted treatments to address sleep quality either prior to or in conjunction with trauma-focused therapy may help to improve treatment outcomes for Veterans with comorbid PTSD and TBI history.

The Bidirectional Relationship Between Sleep and Inflammation Links Traumatic Brain Injury and Alzheimer's Disease

Traumatic brain injury (TBI) and Alzheimer's disease (AD) are diseases during which the fine-tuned autoregulation of the brain is lost. Despite the stark contrast in their causal mechanisms, both TBI and AD are conditions which elicit a neuroinflammatory response that is coupled with physical, cognitive, and affective symptoms. One commonly reported symptom in both TBI and AD patients is disturbed sleep. Sleep is regulated by circadian and homeostatic processes such that pathological inflammation may disrupt the chemical signaling required to maintain a healthy sleep profile. In this way, immune system activation can influence sleep physiology. Conversely, sleep disturbances can exacerbate symptoms or increase the risk of inflammatory/neurodegenerative diseases. Both TBI and AD are worsened by a chronic pro-inflammatory microenvironment which exacerbates symptoms and worsens clinical outcome. Herein, a positive feedback loop of chronic inflammation and sleep disturbances is initiated. In this review, the bidirectional relationship between sleep disturbances and inflammation is discussed, where chronic inflammation associated with TBI and AD can lead to sleep disturbances and exacerbated neuropathology. The role of microglia and cytokines in sleep disturbances associated with these diseases is highlighted. The proposed sleep and inflammation-mediated link between TBI and AD presents an opportunity for a multifaceted approach to clinical intervention.

The role of PTSD and TBI in post-deployment sleep outcomes

The purpose of this study was to evaluate the main and interaction effects of PTSD and TBI on sleep outcomes in veterans. Post-deployment combat veterans (N = 293, 87.37% male) completed clinical interviews to determine diagnosis and severity of PTSD and deployment TBI history, as well as subjective measures of sleep quality, sleep duration, and restedness. Sleep-related medical diagnoses were extracted from electronic medical records for all participants. PTSD and TBI were each associated with poorer ratings of sleep quality, restedness, shorter sleep duration, and greater incidence of clinically diagnosed sleep disorders. Analyses indicated main effects of PTSD on sleep quality (p < .001), but no main effects of TBI. PTSD severity was significantly associated with poorer sleep quality (p < .001), restedness (p = .018), and shorter sleep duration (p = .015). TBI severity was significantly associated with restedness beyond PTSD severity (p = .036). There were no interaction effects between diagnostic or severity variables. PTSD severity is a driving factor for subjective ratings of sleep disturbance beyond PTSD diagnosis as well as TBI diagnosis and severity. Despite this, poor sleep was apparent throughout the sample, which suggests post-deployment service members may globally benefit from routine screening of sleep problems and increased emphasis on sleep hygiene.

The functional roles of IGF-1 variants in the susceptibility and clinical outcomes of mild traumatic brain injury

BACKGROUND

Insulin-like growth factor 1 (IGF-1) is an important pleiotropic hormone that exerts neuroprotective and neuroreparative effects after a brain injury. However, the roles of IGF-1 variants in mild traumatic brain injury (mTBI) are not yet fully understood. This study attempted to elucidate the effects of IGF-1 variants on the risk and neuropsychiatric outcomes of mTBI.

METHODS

Based on 176 recruited mTBI patients and 1517 control subjects from the Taiwan Biobank project, we first compared the genotypic distributions of IGF-1 variants between the two groups. Then, we analyzed associations of IGF-1 variants with neuropsychiatric symptoms after mTBI, including anxiety, depression, dizziness, and sleep disturbances. Functional annotation of IGF-1 variants was also performed through bioinformatics databases.

RESULTS

The minor allele of rs7136446 was over-represented in mTBI patients compared to community-based control subjects. Patients carrying minor alleles of rs7136446 and rs972936 showed more dizziness and multiple neuropsychiatric symptoms after brain injury.

CONCLUSIONS

IGF-1 variants were associated with the risk and neuropsychiatric symptoms of mTBI. The findings highlight the important role of IGF-1 in the susceptibility and clinical outcomes of mTBI.

Acute Post-Traumatic Sleep May Define Vulnerability to a Second Traumatic Brain Injury in Mice

Chronic neurological impairments can manifest from repetitive traumatic brain injury (rTBI), particularly when subsequent injuries occur before the initial injury completely heals. Herein, we apply post-traumatic sleep as a physiological biomarker of vulnerability, hypothesizing that a second TBI during post-traumatic sleep worsens neurological and histological outcomes compared to one TBI or a second TBI after post-traumatic sleep subsides. Mice received sham or diffuse TBI by midline fluid percussion injury; brain-injured mice received one TBI or rTBIs at 3- or 9-h intervals. Over 40 h post-injury, injured mice slept more than shams. Functional assessments indicated lower latencies on rotarod and increased Neurological Severity Scores for mice with rTBIs within 3 h. Anxiety-like behaviors in the open field task were increased for mice with rTBIs at 3 h. Based on pixel density of silver accumulation, neuropathology was greater at 28 days post-injury (DPI) in rTBI groups than sham and single TBI. Cortical microglia morphology was quantified and mice receiving rTBI were de-ramified at 14 DPI compared to shams and mice receiving a single TBI, suggesting robust microglial response in rTBI groups. Orexin-A-positive cells were sustained in the lateral hypothalamus with no loss detected, indicating that loss of wake-promoting neurons did not contribute to post-traumatic sleep. Thus, duration of post-traumatic sleep is a period of vulnerability that results in exacerbated injury from rTBI. Monitoring individual post-traumatic sleep is a potential clinical tool for personalized TBI management, where regular sleep patterns may inform rehabilitative strategies and return-to-activity guidelines.

Treatment of Acute Sports-Related Concussion

PURPOSE OF REVIEW

Here, we summarize the current scientific literature on the management of sports-related concussion (SRC) in the acute period (< 6 weeks post-injury) with a focus on rest, return to learn, return to play, and emerging treatments.

RECENT FINDINGS

While relative rest is recommended for the first 24-48 h following acute SRC, the most recent guidelines highlight the lack of evidence for complete rest and in fact show that prolonged cognitive and physical rest can be detrimental. Gradual return to learn and play is recommended. Return to sport should only occur once the patient is symptom free. While there are no FDA-approved medications for acute treatment of concussion, there is preclinical data for the benefit of omega 3 fatty acids. Evidence is limited around the benefits of treating sleep disorders, vestibular-ocular dysfunction, and neck pain in the acute period. After 24-48 h of rest, SRC patients may gradually resume cognitive and physical activity. More research is needed to determine if any supplements, medications, and/or physical therapy are indicated in the management in acute SRC.

Sleep, Sleep Disorders, and Circadian Health following Mild Traumatic Brain Injury in Adults: Review and Research Agenda

A rapidly expanding scientific literature supports the frequent co-occurrence of sleep and circadian disturbances following mild traumatic brain injury (mTBI). Although many questions remain unanswered, the preponderance of evidence suggests that sleep and circadian disorders can result from mTBI. Among those with mTBI, sleep disturbances and clinical sleep and circadian disorders contribute to the morbidity and long-term sequelae across domains of functional outcomes and quality of life. Specifically, along with deterioration of neurocognitive performance, insufficient and disturbed sleep can precede, exacerbate, or perpetuate many of the other common sequelae of mTBI, including depression, post-traumatic stress disorder, and chronic pain. Further, sleep and mTBI share neurophysiologic and neuroanatomic mechanisms that likely bear directly on success of rehabilitation following mTBI. For these reasons, focus on disturbed sleep as a modifiable treatment target has high likelihood of improving outcomes in mTBI. Here, we review relevant literature and present a research agenda to 1) advance understanding of the reciprocal relationships between sleep and circadian factors and mTBI sequelae and 2) advance rapidly the development of sleep-related treatments in this population.

Trajectory of Parvalbumin Cell Impairment and Loss of Cortical Inhibition in Traumatic Brain Injury

Many neuropsychiatric symptoms that follow traumatic brain injury (TBI), including mood disorders, sleep disturbance, chronic pain, and posttraumatic epilepsy (PTE) are attributable to compromised cortical inhibition. However, the temporal trajectory of cortical inhibition loss and its underlying mechanisms are not known. Using paired-pulse transcranial magnetic stimulation (ppTMS) and immunohistochemistry, we tracked functional and cellular changes of cortical inhibitory network elements after fluid-percussion injury (FPI) in rats. ppTMS revealed a progressive loss of cortical inhibition as early as 2 weeks after FPI. This profile paralleled the increasing levels of cortical oxidative stress, which was accompanied by a gradual loss of parvalbumin (PV) immunoreactivity in perilesional cortex. Preceding the PV loss, we identified a degradation of the perineuronal net (PNN)-a specialized extracellular structure enwrapping cortical PV-positive (PV+) inhibitory interneurons which binds the PV+ cell maintenance factor, Otx2. The trajectory of these impairments underlies the reduced inhibitory tone, which can contribute to posttraumatic neurological conditions, such as PTE. Taken together, our results highlight the use of ppTMS as a biomarker to track the course of cortical inhibitory dysfunction post-TBI. Moreover, the neuroprotective role of PNNs on PV+ cell function suggests antioxidant treatment or Otx2 enhancement as a promising prophylaxis for post-TBI symptoms.

Traumatic Brain Injury, Sleep Disorders, and Psychiatric Disorders: An Underrecognized Relationship

Traumatic brain injury (TBI) is commonplace among pediatric patients and has a complex, but intimate relationship with psychiatric disease and disordered sleep. Understanding the factors that influence the risk for the development of TBI in pediatrics is a critical component of beginning to address the consequences of TBI. Features that may increase risk for experiencing TBI sometimes overlap with factors that influence the development of post-concussive syndrome (PCS) and recovery course. Post-concussive syndrome includes physical, psychological, cognitive and sleep-wake dysfunction. The comorbid presence of sleep-wake dysfunction and psychiatric symptoms can lead to a more protracted recovery and deleterious outcomes. Therefore, a multidisciplinary evaluation following TBI is necessary. Treatment is generally symptom specific and mainly based on adult studies. Further research is necessary to enhance diagnostic and therapeutic approaches, as well as improve the understanding of contributing pathophysiology for the shared development of psychiatric disease and sleep-wake dysfunction following TBI.

Glymphatic system disruption as a mediator of brain trauma and chronic traumatic encephalopathy

Traumatic brain injury (TBI) is an increasingly important issue among veterans, athletes and the general public. Difficulties with sleep onset and maintenance are among the most commonly reported symptoms following injury, and sleep debt is associated with increased accumulation of beta amyloid (Aβ) and phosphorylated tau (p-tau) in the interstitial space. Recent research into the glymphatic system, a lymphatic-like metabolic clearance mechanism in the central nervous system (CNS) which relies on cerebrospinal fluid (CSF), interstitial fluid (ISF), and astrocytic processes, shows that clearance is potentiated during sleep. This system is damaged in the acute phase following mTBI, in part due to re-localization of aquaporin-4 channels away from astrocytic end feet, resulting in reduced potential for waste removal. Long-term consequences of chronic dysfunction within this system in the context of repetitive brain trauma and insomnia have not been established, but potentially provide one link in the explanatory chain connecting repetitive TBI with later neurodegeneration. Current research has shown p-tau deposition in perivascular spaces and along interstitial pathways in chronic traumatic encephalopathy (CTE), pathways related to glymphatic flow; these are the main channels by which metabolic waste is cleared. This review addresses possible links between mTBI-related damage to glymphatic functioning and physiological changes found in CTE, and proposes a model for the mediating role of sleep disruption in increasing the risk for developing CTE-related pathology and subsequent clinical symptoms following repetitive brain trauma.

A narrative literature review of depression following traumatic brain injury: prevalence, impact, and management challenges

Depression is one of the most common conditions to emerge after traumatic brain injury (TBI), and despite its potentially serious consequences it remains undertreated. Treatment for post-traumatic depression (PTD) is complicated due to the multifactorial etiology of PTD, ranging from biological pathways to psychosocial adjustment. Identifying the unique, personalized factors contributing to the development of PTD could improve long-term treatment and management for individuals with TBI. The purpose of this narrative literature review was to summarize the prevalence and impact of PTD among those with moderate to severe TBI and to discuss current challenges in its management. Overall, PTD has an estimated point prevalence of 30%, with 50% of individuals with moderate to severe TBI experiencing an episode of PTD in the first year after injury alone. PTD has significant implications for health, leading to more hospitalizations and greater caregiver burden, for participation, reducing rates of return to work and affecting social relationships, and for quality of life. PTD may develop directly or indirectly as a result of biological changes after injury, most notably post-injury inflammation, or through psychological and psychosocial factors, including pre injury personal characteristics and post-injury adjustment to disability. Current evidence for effective treatments is limited, although the strongest evidence supports antidepressants and cognitive behavioral interventions. More personalized approaches to treatment and further research into unique therapy combinations may improve the management of PTD and improve the health, functioning, and quality of life for individuals with TBI.

Sleep-Wake Disturbances After Traumatic Brain Injury: Synthesis of Human and Animal Studies

Sleep-wake disturbances following traumatic brain injury (TBI) are increasingly recognized as a serious consequence following injury and as a barrier to recovery. Injury-induced sleep-wake disturbances can persist for years, often impairing quality of life. Recently, there has been a nearly exponential increase in the number of primary research articles published on the pathophysiology and mechanisms underlying sleep-wake disturbances after TBI, both in animal models and in humans, including in the pediatric population. In this review, we summarize over 200 articles on the topic, most of which were identified objectively using reproducible online search terms in PubMed. Although these studies differ in terms of methodology and detailed outcomes; overall, recent research describes a common phenotype of excessive daytime sleepiness, nighttime sleep fragmentation, insomnia, and electroencephalography spectral changes after TBI. Given the heterogeneity of the human disease phenotype, rigorous translation of animal models to the human condition is critical to our understanding of the mechanisms and of the temporal course of sleep-wake disturbances after injury. Arguably, this is most effectively accomplished when animal and human studies are performed by the same or collaborating research programs. Given the number of symptoms associated with TBI that are intimately related to, or directly stem from sleep dysfunction, sleep-wake disorders represent an important area in which mechanistic-based therapies may substantially impact recovery after TBI.

Hypocretinergic and cholinergic contributions to sleep-wake disturbances in a mouse model of traumatic brain injury

Disorders of sleep and wakefulness occur in the majority of individuals who have experienced traumatic brain injury (TBI), with increased sleep need and excessive daytime sleepiness often reported. Behavioral and pharmacological therapies have limited efficacy, in part, because the etiology of post-TBI sleep disturbances is not well understood. Severity of injuries resulting from head trauma in humans is highly variable, and as a consequence so are their sequelae. Here, we use a controlled laboratory model to investigate the effects of TBI on sleep-wake behavior and on candidate neurotransmitter systems as potential mediators. We focus on hypocretin and melanin-concentrating hormone (MCH), hypothalamic neuropeptides important for regulating sleep and wakefulness, and two potential downstream effectors of hypocretin actions, histamine and acetylcholine. Adult male C57BL/6 mice (n=6-10/group) were implanted with EEG recording electrodes and baseline recordings were obtained. After baseline recordings, controlled cortical impact was used to induce mild or moderate TBI. EEG recordings were obtained from the same animals at 7 and 15 days post-surgery. Separate groups of animals (n=6-8/group) were used to determine effects of TBI on the numbers of hypocretin and MCH-producing neurons in the hypothalamus, histaminergic neurons in the tuberomammillary nucleus, and cholinergic neurons in the basal forebrain. At 15 days post-TBI, wakefulness was decreased and NREM sleep was increased during the dark period in moderately injured animals. There were no differences between groups in REM sleep time, nor were there differences between groups in sleep during the light period. TBI effects on hypocretin and cholinergic neurons were such that more severe injury resulted in fewer cells. Numbers of MCH neurons and histaminergic neurons were not altered under the conditions of this study. Thus, we conclude that moderate TBI in mice reduces wakefulness and increases NREM sleep during the dark period, effects that may be mediated by hypocretin-producing neurons and/or downstream cholinergic effectors in the basal forebrain.

Sleep disturbances, TBI and PTSD: Implications for treatment and recovery

Post-Traumatic Stress Disorder (PTSD), traumatic brain injury (TBI), and sleep problems significantly affect recovery and functional status in military personnel and Veterans returning from combat. Despite recent attention, sleep is understudied in the Veteran population. Few treatments and rehabilitation protocols target sleep, although poor sleep remains at clinical levels and continues to adversely impact functioning even after the resolution of PTSD or mild TBI symptoms. Recent developments in non-pharmacologic sleep treatments have proven efficacious as stand-alone interventions and have potential to improve treatment outcomes by augmenting traditional behavioral and cognitive therapies. This review discusses the extensive scope of work in the area of sleep as it relates to TBI and PTSD, including pathophysiology and neurobiology of sleep; existing and emerging treatment options; as well as methodological issues in sleep measurements for TBI and PTSD. Understanding sleep problems and their role in the development and maintenance of PTSD and TBI symptoms may lead to improvement in overall treatment outcomes while offering a non-stigmatizing entry in mental health services and make current treatments more comprehensive by helping to address a broader spectrum of difficulties.

REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy

Sleep can foster the reorganization of memory, i.e. the emergence of new memory content that has not directly been encoded. Current neurophysiological and behavioral evidence can be integrated into a model positing that REM sleep particularly promotes the disintegration of existing schemas and their recombination in the form of associative thinking, creativity and the shaping of emotional memory. Particularly, REM sleep related dreaming might represent a mentation correlate for the reconfiguration of memory. In a final section, the potential relevance for psychiatry and psychotherapy is discussed.