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

Effects of mTBI with loss of consciousness on neurobehavioral symptoms, depression, and insomnia in former collegiate and NFL football athletes

OBJECTIVE

Considering that diagnostic decisions about mTBI are often predicated on clinical symptom criteria, it is imperative to determine which initial presentation features of mTBI have prognostic significance for identifying those at high risk for long-term functional impairment.

SETTING

Zoom interview Participants: Male, former NCAA Division I, and professional-level National Football League (NFL) athletes (n = 177) between the ages of 27 and 85 (M = 54.1, SD = 14.7).

DESIGN

Cross-sectional case-control. Main Measures: History of mild TBI, history of loss of consciousness (LOC), depression symptoms, insomnia, neurobehavioral symptoms.

RESULTS

Number of mTBI exposures did not predict neurobehavioral symptoms (B = 0.21, SE = 0.18, p = 0.23), but number of mTBI + LOC events did (B = 2.27, SE = 0.64, p = <.001). Further analysis revealed that the number of mTBI + LOC events predicted neurobehavioral symptoms indirectly through both depression (B = 0.85, 95% CI = [0.27, 1.52) and insomnia (B = 0.81, 95% CI = [0.3, 1.4]). Further, the direct effect of mTBI + LOC events on neurobehavioral symptoms became non-significant when depression and insomnia were added to the model (B = 0.78, SE = 0.45, p = 0.08).

CONCLUSIONS

Findings support LOC at time of injury as an important predictor of long-term outcomes. Additionally, results suggest depression and insomnia as potential mediators in the association between mTBI + LOC and neurobehavioral symptoms. These findings provide justification for early depression and insomnia symptom monitoring following mTBI + LOC.

Subclinical brain manifestations of repeated mild traumatic brain injury are changed by chronic exposure to sleep loss, caffeine, and sleep aids

INTRODUCTION

After mild traumatic brain injury (mTBI), the brain is labile for weeks and months and vulnerable to repeated concussions. During this time, patients are exposed to everyday circumstances that, in themselves, affect brain metabolism and blood flow and neural processing. How commonplace activities interact with the injured brain is unknown. The present study in an animal model investigated the extent to which three commonly experienced exposures-daily caffeine usage, chronic sleep loss, and chronic sleep aid medication-affect the injured brain in the chronic phase.

METHODS

Subclinical trauma by repeated mTBIs was produced by our head rotational acceleration injury model, which causes brain injury consistent with the mechanism of concussion in humans. Forty-eight hours after a third mTBI, chronic administrations of caffeine, sleep restriction, or zolpidem (sedative hypnotic) began and were continued for 70 days. On Days 30 and 60 post injury, resting state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) were performed.

RESULTS

Chronic caffeine, sleep restriction, and zolpidem each changed the subclinical brain characteristics of mTBI at both 30 and 60 days post injury, detected by different MRI modalities. Each treatment caused microstructural alterations in DTI metrics in the insular cortex and retrosplenial cortex compared with mTBI, but also uniquely affected other gray and white matter regions. Zolpidem administration affected the largest number of individual structures in mTBI at both 30 and 60 days, and not necessarily toward normalization (sham treatment). Chronic sleep restriction changed local functional connectivity at 30 days in diametrical opposition to chronic caffeine ingestion, and both treatment outcomes were different from sham, mTBI-only and zolpidem comparisons. The results indicate that commonly encountered exposures modify subclinical brain activity and structure long after healing is expected to be complete.

CONCLUSIONS

Changes in activity and structure detected by fMRI are widely understood to reflect changes in the functions of the affected region which conceivably underlie mTBI neuropathology and symptomatology in the chronic phase after injury.

Longitudinal assessment of glymphatic changes following mild traumatic brain injury: Insights from perivascular space burden and DTI-ALPS imaging

Introduction

Traumatic brain injury (TBI) even in the mild form may result in long-lasting post-concussion symptoms. TBI is also a known risk to late-life neurodegeneration. Recent studies suggest that dysfunction in the glymphatic system, responsible for clearing protein waste from the brain, may play a pivotal role in the development of dementia following TBI. Given the diverse nature of TBI, longitudinal investigations are essential to comprehending the dynamic changes in the glymphatic system and its implications for recovery.

Methods

In this prospective study, we evaluated two promising glymphatic imaging markers, namely the enlarged perivascular space (ePVS) burden and Diffusion Tensor Imaging-based ALPS index, in 44 patients with mTBI at two early post-injury time points: approximately 14 days (14Day) and 6-12 months (6-12Mon) post-injury, while also examining their associations with post-concussion symptoms. Additionally, 37 controls, comprising both orthopedic patients and healthy individuals, were included for comparative analysis.

Results

Our key findings include: (1) White matter ePVS burden (WM-ePVS) and ALPS index exhibit significant correlations with age. (2) Elevated WM-ePVS burden in acute mTBI (14Day) is significantly linked to a higher number of post-concussion symptoms, particularly memory problems. (3) The increase in the ALPS index from acute (14Day) to the chronic (6-12Mon) phases in mTBI patients correlates with improvement in sleep measures. Furthermore, incorporating WM-ePVS burden and the ALPS index from acute phase enhances the prediction of chronic memory problems beyond socio-demographic and basic clinical information.

Conclusion

ePVS burden and ALPS index offers distinct values in assessing glymphatic structure and activity. Early evaluation of glymphatic function could be crucial for understanding TBI recovery and developing targeted interventions to improve patient outcomes.

Traumatic brain injury and sleep in military and veteran populations: A literature review

BACKGROUND

Traumatic brain injury (TBI) is a hallmark of wartime injury and is related to numerous sleep wake disorders (SWD), which persist long term in veterans. Current knowledge gaps in pathophysiology have hindered advances in diagnosis and treatment.

OBJECTIVE

We reviewed TBI SWD pathophysiology, comorbidities, diagnosis and treatment that have emerged over the past two decades.

METHODS

We conducted a literature review of English language publications evaluating sleep disorders (obstructive sleep apnea, insomnia, hypersomnia, parasomnias, restless legs syndrome and periodic limb movement disorder) and TBI published since 2000. We excluded studies that were not specifically evaluating TBI populations.

RESULTS

Highlighted areas of interest and knowledge gaps were identified in TBI pathophysiology and mechanisms of sleep disruption, a comparison of TBI SWD and post-traumatic stress disorder SWD. The role of TBI and glymphatic biomarkers and management strategies for TBI SWD will also be discussed.

CONCLUSION

Our understanding of the pathophysiologic underpinnings of TBI and sleep health, particularly at the basic science level, is limited. Developing an understanding of biomarkers, neuroimaging, and mixed-methods research in comorbid TBI SWD holds the greatest promise to advance our ability to diagnose and monitor response to therapy in this vulnerable population.

Sleep After Concussion: A Scoping Review of Sensor Technologies

Sleep disturbances following a concussion/mild traumatic brain injury are associated with longer recovery times and more comorbidities. Sensor technologies can directly monitor sleep-related physiology and provide objective sleep metrics. This scoping review determines how sensor technologies are currently used to monitor sleep following a concussion. We searched Ovid (Medline, Embase), Web of Science, CINAHL, Compendex Engineering Village, and PsycINFO from inception to June 20, 2022, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for scoping reviews. Included studies objectively monitored sleep in participants with concussion. We screened 1081 articles and included 37 in the review. A total of 17 studies implemented polysomnography (PSG) months to years after injury for a median of two nights and provided a wide range of sleep metrics, including sleep-wake times, sleep stages, arousal indices, and periodic limb movements. Twenty-two studies used actigraphy days to weeks after injury for a median of 10 days and nights and provided information limited to sleep-wake times. Sleep stages were most reported in PSG studies, and sleep efficiency was most reported in actigraphy studies. For both technologies there was high variability in reported outcome measures. Sleep sensing technologies may be used to identify how sleep affects concussion recovery. However, high variability in sensor deployment methodologies makes cross-study comparisons difficult and highlights the need for standardization. Consensus on how sleep sensing technologies are used post-concussion may lead to clinical integration with subjective methods for improved sleep monitoring during the recovery period.

Assessment of sleep parameters in adults with persistent post-concussive symptoms

OBJECTIVES

The primary aim of this study was to characterize sleep in adults with persistent post-concussive symptoms (PPCS). Secondary aims explored relationships between sleep parameters, injury characteristics, and symptom questionnaires.

METHODS

This case-controlled, cross-sectional study recruited adults (18-65yrs) diagnosed with PPCS and age and sex-matched controls. Participants wore a wrist-worn actigraph for 3-7 nights and completed daily sleep diaries. Participants completed questionnaires examining daytime sleepiness, fatigue, anxiety/depressive symptoms, and sedentariness. Sleep parameters were compared between groups using Mann-Whitney U tests. Secondary analyses used two-way ANOVA and Spearman's rank correlations.

RESULTS

Fifty adults with PPCS (43.7 ± 10.6yrs, 78 % female) and 50 controls (43.6 ± 11.0yrs) were included in this study. Adults with PPCS had significantly longer sleep onset latency (PPCS 16.99 ± 14.51min, Controls 8.87 ± 6.44min, p < 0.001) and total sleep time (PPCS 8.3 ± 1.0hrs, Control 7.6 ± 0.9hrs, p = 0.030) compared to controls, but woke up later (PPCS 7:57:27 ± 1:36:40, Control 7:17:16 ± 0:50:08, p = 0.026) and had poorer sleep efficiency (PPCS 77.9 ± 7.5 %, Control 80.8 ± 6.0 %, p = 0.019) than controls. Adults with PPCS reported more daytime sleepiness (Epworth Sleepiness Scale: PPCS 8.70 ± 4.61, Control 4.28 ± 2.79, p < 0.001) and fatigue (Fatigue Severity Scale: PPCS 56.54 ± 12.92, Control 21.90 ± 10.38, p < 0.001). Injury characteristics did not significantly affect sleep parameters in adults with PPCS. Actigraphy parameters were not significantly correlated to questionnaire measures.

CONCLUSION

Several actigraphy sleep parameters were significantly altered in adults with PPCS compared to controls, but did not correlate with sleep questionnaires, suggesting both are useful tools in characterizing sleep in PPCS. Further, this study provides potential treatment targets to improve sleep difficulties in adults with PPCS.

Cognitive Behavioral Therapy for Insomnia Improves Sleep Outcomes in Individuals With Concussion: A Preliminary Randomized Wait-List Control Study

OBJECTIVE

Cognitive behavioral therapy for insomnia (CBT-I) is the gold standard treatment for insomnia, but there is limited evidence on the treatment effect of CBT-I in individuals after a concussion. Therefore, the main purpose of this study was to evaluate the treatment effect of CBT-I on sleep outcomes and postconcussion symptoms.

SETTING

This study was conducted at an academic institution. The CBT-I sessions were conducted using a teleconferencing system (Zoom).

PARTICIPANTS

Participants were eligible to participate if they were at least 4 weeks post- concussion, aged 18 to 64 years, and scored 10 or more on the Insomnia Severity Index. A total of 40 people were enrolled; 32 participants were included in analyses.

DESIGN

This was a randomized controlled wait-list study. Participants were randomized into starting the CBT-I intervention immediately after the baseline assessment or into the wait-list group for 6 weeks before starting CBT-I. Assessments were performed at baseline, 6, 12, and 18 weeks.

MAIN MEASURES

The primary outcome was the Insomnia Severity Index. Secondary measures included the Pittsburg Sleep Quality Index, Post-Concussion Symptom Scale, and Beck Depression and Anxiety Inventories. Statistical analyses included a repeated-measures analysis of variance, t tests, and mixed linear regression modeling.

RESULTS

There was a group-by-time interaction for the sleep outcomes but not for the concussion or mood outcomes. Differences were seen between groups on sleep outcomes, symptom severity, and depression. The treatment effect was maintained following CBT-I for all outcomes. Improvement in sleep outcomes was predictive of improvement in postconcussion symptom severity and number of symptoms.

CONCLUSIONS

CBT-I reduces insomnia in individuals with concussions, and improved sleep was associated with lower postconcussion and mood symptoms. These effects were maintained 6 to 12 weeks following the intervention.

Effects of Blast-and Impact-Related Concussion on Persistent Sleep Problems

OBJECTIVE

Examine whether concussion mechanism of injury (high-level blast [HLB] vs impact) affects the likelihood of persistent sleep problems in a post-deployment military population.

SETTING

Post-Deployment Health Assessment and Re-Assessment survey records completed upon return from deployment and approximately 6 months later.

PARTICIPANTS

Active duty enlisted US Marines who completed both assessments (N = 64 464).

DESIGN

This retrospective cohort study investigated US Marines deployed between 2008 and 2012. Logistic regression was used to examine persistent sleep problems 6 months after return from deployment.

MAIN MEASURES

Self-reported sleep problems at reassessment were investigated as the outcome. Predictors included HLB-induced concussions (mbTBI vs none), impact-induced concussions (miTBI vs none), occupational risk of low-level blast, probable posttraumatic stress disorder (PTSD), depression, alcohol misuse, sleep problems upon deployment return, and relevant interactions, adjusting for sex and pay grade.

RESULTS

With the exception of sex, all main effects in the model were associated with greater likelihood of reporting persistent sleep problems at reassessment. Sleep problems at return from deployment showed the strongest associations with likelihood of reporting sleep problems at reassessment, followed by mbTBI. The latter was exacerbated by PTSD and depression.

CONCLUSION

mbTBI (vs miTBI) may be more strongly associated with persistent sleep issues that warrant additional monitoring and treatment, particularly among those with probable PTSD and/or depression.

Longitudinal Assessment of Glymphatic Changes Following Mild Traumatic Brain Injury: Insights from PVS burden and DTI-ALPS Imaging

Traumatic brain injury (TBI) even in the mild form may result in long-lasting post-concussion symptoms. TBI is also a known risk to late-life neurodegeneration. Recent studies suggest that dysfunction in the glymphatic system, responsible for clearing protein waste from the brain, may play a pivotal role in the development of dementia following TBI. Given the diverse nature of TBI, longitudinal investigations are essential to comprehending the dynamic changes in the glymphatic system and its implications for recovery. In this prospective study, we evaluated two promising glymphatic imaging markers, namely the enlarged perivascular space (ePVS) burden and Diffusion Tensor Imaging-based ALPS index, in 44 patients with mTBI at two early post-injury time points: approximately 14 days (14Day) and 6-12 months (6-12Mon) post-injury, while also examining their associations with post-concussion symptoms. Additionally, 37 controls, comprising both orthopedic patients and healthy individuals, were included for comparative analysis. Our key findings include: 1) White matter ePVS burden (WM-ePVS) and ALPS index exhibit significant correlations with age. 2) Elevated WM-ePVS burden in acute mTBI (14Day) is significantly linked to a higher number of post-concussion symptoms, particularly memory problems. 3) The increase in the ALPS index from acute (14Day) to the chronic (6-12Mon) phases in mTBI patients correlates with improvement in sleep measures. Furthermore, incorporating WM-ePVS burden and the ALPS index from acute phase enhances the prediction of chronic memory problems beyond socio-demographic and basic clinical information, highlighting their distinct roles in assessing glymphatic structure and activity. Early evaluation of glymphatic function could be crucial for understanding TBI recovery and developing targeted interventions to improve patient outcomes.

Sleep Disruption Persists and Relates to Memory Disability After Traumatic Brain Injury: A Cross-Sectional Study of Adults in the Chronic Phase of Injury

OBJECTIVE

To examine sleep disruption in chronic traumatic brain injury (TBI) across 3 aims: (1) to examine differences in self-reported sleep disruption between adults with and without a chronic history of TBI; (2) to query reported changes in sleep after TBI; and (3) to explore the relationship between self-reported sleep disruption and memory failures in daily life.

SETTING

Community-dwelling participants completed self-report sleep and memory surveys as part of their participation in a larger patient registry.

PARTICIPANTS

This study included 258 participants, and half (n = 129) of them have a chronic history of moderate-severe TBI (mean time since injury is 5.1 [SD 6.5] years).

DESIGN

We report descriptive statistics from this matched cross-sectional study on sleep in the chronic phase of injury. We also used planned Wilcoxon ranked-sum tests and exploratory correlations to examine the relationships of sleep disruption with TBI diagnosis, injury chronicity, and memory.

MAIN MEASURES

We used the Pittsburgh Sleep Quality Index to measure sleep disruption and the Epworth Sleepiness Scale to measure daytime sleepiness. Participants answered questions about postinjury sleep and responded to the Everyday Memory Questionnaire as a measure of memory failures in daily life.

RESULTS

Individuals with TBI had significantly higher rates of sleep disruption than those without TBI, as measured by the Pittsburgh Sleep Quality Index but not on the Epworth Sleepiness Scale. Sleep disruption in TBI manifested more in sleep quality than quantity. Half of the participants with TBI reported a negative change in sleep postinjury. In an exploratory analysis, sleep disruption was related to memory failure in daily life in the TBI sample.

CONCLUSIONS

Sleep disruption persists long after TBI but may be under-recognized in people with chronic TBI. Given that sleep is critical for memory and rehabilitation outcomes well into the chronic phase of injury, steps to improve the identification and management of sleep disruption are needed. Key words:chronic, memory, sleep, traumatic brain injury.

Measurement of Sleep in Chronic Traumatic Brain Injury: Relationship Between Self-report and Actigraphy

OBJECTIVE

To examine the relationship between self-report and actigraphy measurement of sleep in people with and without traumatic brain injury (TBI) by addressing 2 aims: (1) to assess the relationship between self-report and actigraphy for sleep quantity in people with and without TBI; and (2) to explore how self-report and actigraphy capture sleep quality in TBI.

SETTING

Participants completed the study over 2 weeks in their own homes. They wore activity monitors, day and night, throughout the experiment and completed morning sleep diaries while interacting with an experimenter on videoconference.

PARTICIPANTS

This project was embedded in a larger study on sleep and word learning in 100 adults: 50 with chronic, moderate-severe TBI and 50 demographically matched noninjured peers. Of the 100 participants who completed the larger study, 92 participants (45 with TBI and 47 noninjured peers) had sufficient actigraphy data for inclusion in the current study.

DESIGN

We used multilevel linear regression models and correlation analyses to assess how well participants' self-report corresponded to actigraphy measurement of sleep.

MAIN MEASURES

Actigraphy measures included nightly sleep duration and nighttime wakeups. Sleep diary measures included self-reported nightly sleep duration, nighttime wakeups, sleep quality, and morning fatigue.

RESULTS

People with and without TBI did not differ in the relationship between self-reported and actigraphy measurement of sleep quantity. Performance on a neuropsychological memory assessment did not correlate with the difference in self-reported and actigraphy-measured sleep in the TBI group. Sleep characteristics that were measured by actigraphy did not predict subjective experiences of sleep quality or fatigue.

CONCLUSIONS

Short-term self-report diaries capture accurate information about sleep quantity in individuals with TBI and may support self-report of other daily habits. Future research is needed to identify reliable metrics of sleep quality, and how they relate to other domains such as memory and mood, in the chronic phase of TBI.

Heterogeneity of health-related quality of life after mild traumatic brain injury with systemic injury: a cluster analytic approach

PURPOSE

Health-related quality of life (HRQoL) is a key component of evaluating outcome after mild traumatic brain injury (mTBI). As outcome is heterogeneous following mTBI, it is relevant to examine individual differences in HRQoL. This study investigated whether multiple homogenous subgroups could be meaningfully identified, 10 weeks after hospitalised mTBI with systemic injury, on the basis of HRQoL profiles.

METHODS

Ninety-one adults were assessed for HRQoL, pain, fatigue, sleep quality, psychological distress, cognition and post-concussion symptoms.

RESULTS

Cluster analyses revealed three separate subgroups based on physical, mental, social and energy HRQoL. One group (42%) demonstrated normative levels of HRQoL on all subdomains. The remaining two groups demonstrated significantly reduced HRQoL on all subdomains. These groups had equivalently poor mental, social and energy HRQoL, but the smallest group (27%) had significantly poorer physical HRQoL. Multinomial logistic regression revealed that pain significantly and independently predicted group membership for the particularly poor physical HRQoL group. Fatigue was the only significant independent predictor of group membership for the remaining group with reduced HRQoL.

CONCLUSION

These findings suggest more than 50% of hospitalised individuals with mTBI and systemic injury, have reduced HRQoL, 10 weeks after mTBI. Pain and fatigue warrant clinical attention in these individuals.IMPLICATIONS FOR REHABILITATIONMild traumatic brain injury is a common event that has been shown to be associated with persistently reduced health-related quality of life in approximately 50% of individuals 6 to 12 months after injury.Health-related quality of life likely varies between individuals after injuryRelative to the "normal" population, most individuals in this cohort of individuals with mTBI and systemic injury had reduced mental, social and energy quality of life 10 weeks after injury.Fatigue and pain are important factors in reduced health-related quality of life after mTBI with systemic injury.Further research is needed to determine whether these fatigue and pain issues are related to mTBI-factors, such as headache, and/or related to systemic injury factors, which are common in the mTBI population.

Impact of dementia and socioeconomic disadvantage on days at home after traumatic brain injury among older Medicare beneficiaries: A cohort study

INTRODUCTION

Time spent at home may aid in understanding recovery following traumatic brain injury (TBI) among older adults, including those with Alzheimer's disease and related dementias (ADRD). We examined the impact of ADRD on recovery following TBI and determined whether socioeconomic disadvantages moderated the impact of ADRD.

METHODS

We analyzed Medicare beneficiaries aged ≥65 years diagnosed with TBI in 2010-2018. Home time was calculated by subtracting days spent in a care environment or deceased from total follow-up, and dual eligibility for Medicaid was a proxy for socioeconomic disadvantage.

RESULTS

A total of 2463 of 20,350 participants (12.1%) had both a diagnosis of ADRD and were Medicaid dual-eligible. Beneficiaries with ADRD and Medicaid spent markedly fewer days at home following TBI compared to beneficiaries without either condition (rate ratio 0.66; 95% confidence interval [CI] 0.64, 0.69).

DISCUSSION

TBI resulted in a significant loss of home time over the year following injury among older adults with ADRD, particularly for those who were economically vulnerable.

HIGHLIGHTS

Remaining at home after serious injuries such as fall-related traumatic brain injury (TBI) is an important goal for older adults. No prior research has evaluated how ADRD impacts time spent at home after TBI. Older TBI survivors with ADRD may be especially vulnerable to loss of home time if socioeconomically disadvantaged. We assessed the impact of ADRD and poverty on a novel DAH measure after TBI. ADRD-related disparities in DAH were significantly magnified among those living with socioeconomic disadvantage, suggesting a need for more tailored care approaches.

Symptoms Associated With Exercise Intolerance and Resting Heart Rate Following Mild Traumatic Brain Injury

OBJECTIVES

People may experience a myriad of symptoms after mild traumatic brain injury (mTBI), but the relationship between symptoms and objective assessments is poorly characterized. This study sought to investigate the association between symptoms, resting heart rate (HR), and exercise tolerance in individuals following mTBI, with a secondary aim to examine the relationship between symptom-based clinical profiles and recovery.

METHODS

Prospective observational study of adults aged 18 to 65 years who had sustained mTBI within the previous 7 days. Symptoms were assessed using the Post-Concussion Symptom Scale, HR was measured at rest, and exercise tolerance was assessed using the Buffalo Concussion Bike Test. Symptom burden and symptom-based clinical profiles were examined with respect to exercise tolerance and resting HR.

RESULTS

Data from 32 participants were assessed (mean age 36.5 ± 12.6 years, 41% female, 5.7 ± 1.1 days since injury). Symptom burden (number of symptoms and symptom severity) was significantly associated with exercise intolerance (P = .002 and P = .025, respectively). Physiological and vestibular-ocular clinical profile composite groups were associated with exercise tolerance (P = .001 and P = .014, respectively), with individuals who were exercise intolerant having a higher mean number of symptoms in each profile than those who were exercise tolerant. Mood-related and autonomic clinical profiles were associated with a higher resting HR (>80 bpm) (P = .048 and P = .028, respectively), suggesting altered autonomic response for participants with symptoms relating to this profile. After adjusting for age and mechanism of injury (sports- or non-sports-related), having a higher mood-related clinical profile was associated with persisting symptoms at 3 months postinjury (adjusted odds ratio = 2.08; 95% CI, 1.11-3.90; P = .013).

CONCLUSION

Symptom-based clinical profiles, in conjunction with objective measures such as resting HR and exercise tolerance, are important components of clinical care for those having sustained mTBI. These results provide preliminary support for the concept that specific symptoms are indicative of autonomic dysfunction following mTBI.

The Effect of Concussion Mechanism of Injury on Sleep Problems in Active Duty Service Members Following Deployment

INTRODUCTION

Sleep disruption is pervasive in the military and is generally exacerbated during deployment, partially due to increases in operational tempo and exposure to stressors and/or trauma. In particular, sleep disruption is a commonly reported symptom following deployment-related traumatic brain injury (TBI), though less is known about the prevalence of sleep disturbance as a function of whether the TBI was induced by high-level blast (HLB) or direct impact to the head. TBI assessment, treatment, and prognosis are further complicated by comorbidity with posttraumatic stress disorder (PTSD), depression, and alcohol misuse. Here, we examine whether concussion mechanism of injury is associated with differences in the prevalence of self-reported sleep disturbance following deployment in a large sample of U.S. Marines while accounting for probable PTSD, depression, and alcohol misuse.

MATERIALS AND METHODS

This was a retrospective cohort study of active duty enlisted Marines with a probable concussion (N = 5757) who completed the Post-Deployment Health Assessment between 2008 and 2012. Probable concussion was defined as endorsement of a potentially concussive event with corresponding loss or alteration of consciousness. The presence of concussion-related sleep problems was assessed with a dichotomous item. Probable PTSD, depression, and alcohol misuse were assessed using the Primary Care PTSD Screen, the Patient Health Questionnaire-2, and the Alcohol Use Identification Test-Concise, respectively. Logistic regression models investigated the effects of mechanism of injury (HLB vs. impact), PTSD, depression, and alcohol misuse on the presence of sleep problems, adjusting for sex and pay grade. The study was approved by the Naval Health Research Center Institutional Review Board.

RESULTS

Approximately 41% of individuals with a probable deployment-related concussion reported sleep problems following the event; 79% of concussed individuals reporting both HLB and probable PTSD reported sleep problems. All main effects were significantly associated with sleep disturbance in adjusted models. PTSD showed the strongest association with sleep disturbance (adjusted odds ratio [AOR] = 2.84), followed by depression (AOR = 2.43), HLB exposure (AOR = 2.00), female sex (AOR = 1.63), alcohol misuse (AOR = 1.14), and pay grade (AOR = 1.10). A significant HLB × PTSD interaction emerged (AOR = 1.58), which suggests that sleep disturbance was elevated among those with both HLB-induced (vs. impact-induced) concussions and presence (vs. absence) of PTSD. No other significant interactions emerged.

CONCLUSION

To our knowledge, this is the first study to examine the prevalence of concussion-related sleep complaints following deployment as a function of the mechanism of injury in individuals with and without probable PTSD and depression. Individuals with HLB-induced concussion were twice as likely to report sleep problems as those with an impact-induced concussion. Future work should examine these effects longitudinally with validated measures that assess greater precision of exposure and outcome assessment (e.g., blast intensity and type of sleep disturbance).

Association Between Insomnia and Mental Health and Neurocognitive Outcomes Following Traumatic Brain Injury

We previously described five trajectories of insomnia (each defined by a distinct pattern of insomnia severity over 12 months following traumatic brain injury [TBI]). Our objective in the present study was to estimate the association between insomnia trajectory status and trajectories of mental health and neurocognitive outcomes during the 12 months after TBI. In this study, participants included N = 2022 adults from the Federal Inter-agency Traumatic Brain Injury Repository database and Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study. The following outcome measures were assessed serially at 2 weeks, and 3, 6, and 12 months post-injury: Insomnia Severity Index, Patient Health Questionnaire, Post-Traumatic Stress Disorder (PTSD) Checklist for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), Patient Reported Outcomes Measurement Information System-Pain, and Quality of Life After Brain Injury-Overall Scale. Neurocognitive performance was assessed at 2 weeks, and 6 and 12 months using the Wechsler Adult Intelligence Scales Processing Speed Index and the Trails Making Test Parts A and B. Results indicated that greater insomnia severity was associated with greater abnormality in mental health, quality of life, and neuropsychological testing outcomes. The pattern of insomnia over time tracked the temporal pattern of all these outcomes for all but a very small number of participants. Notably, severe insomnia at 3 or 6 months post-TBI was a risk factor for poor recovery at 12 months post-injury. In conclusion, in this well-characterized sample of individuals with TBI, insomnia severity generally tracked severity of depression, pain, PTSD, quality of life, and neurocognitive outcomes over 12 months post-injury. More intensive sleep assessment is needed to elucidate the nature of these relationships and to help inform best strategies for intervention.

Divergent Spatial Learning, Enhanced Neuronal Transcription, and Blood-Brain Barrier Disruption Develop During Recovery from Post-Injury Sleep Fragmentation

Traumatic brain injury (TBI) causes pathophysiology that may significantly decrease quality of life over time. A major propagator of this response is chronic, maladaptive neuroinflammation, which can be exacerbated by stressors such as sleep fragmentation (SF). This study determined whether post-TBI SF had lasting behavioral and inflammatory effects even with a period of recovery. To test this, male and female mice received a moderate lateral fluid percussion TBI or sham surgery. Half the mice were left undisturbed, and half were exposed to daily SF for 30 days. All mice were then undisturbed between 30 and 60 days post-injury (DPI), allowing mice to recover from SF (SF-R). SF-R did not impair global Barnes maze performance. Nonetheless, TBI SF-R mice displayed retrogression in latency to reach the goal box within testing days. These nuanced behavioral changes in TBI SF-R mice were associated with enhanced expression of neuronal processing/signaling genes and indicators of blood-brain barrier (BBB) dysfunction. Aquaporin-4 (AQP4) expression, a marker of BBB integrity, was differentially altered by TBI and TBI SF-R. For example, TBI enhanced cortical AQP4 whereas TBI SF-R mice had the lowest cortical expression of perivascular AQP4, dysregulated AQP4 polarization, and the highest number of CD45+ cells in the ipsilateral cortex. Altogether, post-TBI SF caused lasting, divergent behavioral responses associated with enhanced expression of neuronal transcription and BBB disruption even after a period of recovery from SF. Understanding lasting impacts from post-TBI stressors can better inform both acute and chronic post-injury care to improve long-term outcome post-TBI.

Links between Sleep Apnoea and Insomnia in a British Cohort

Poor sleep is a major public health problem with implications for a wide range of critical health outcomes. Insomnia and sleep apnoea are the two most common causes of poor sleep, and recent studies have shown that these disorders frequently co-occur. Comorbid insomnia and sleep apnoea can substantially impair quality of life and increase the overall risk of mortality. However, the causal and physiological links between sleep apnoea and insomnia are unclear. It is also unknown whether having a higher risk for one condition can increase the risk of developing the other. Here, we investigated links between sleep apnoea and insomnia in a British population using a combination of self-reported questionnaires and causal inference. We found that 54.3% of the cohort had moderate insomnia, 9.4% had moderate sleep apnoea, and that 6.2% scored high for both conditions. Importantly, having a higher risk of sleep apnoea was associated with a higher risk of insomnia and vice versa. To determine the causal directionality between sleep apnoea and insomnia, we used Mendelian randomisation and found evidence that sleep apnoea could cause insomnia, but not the reverse. To elucidate how both sleep apnoea and insomnia were linked to each other, we looked at the behavioural markers of poor sleep. We found that feeling fatigued after sleeping and having noticeable sleep problems were linked to a higher burden of both sleep apnoea and insomnia. In conclusion, our results show that sleep apnoea increases the risk of developing insomnia, and both conditions can result in fatigue. We highlight the importance of considering and treating the symptoms of both conditions.

BRCA1 heterozygosity promotes DNA damage-induced senescence in a sex-specific manner following repeated mild traumatic brain injury

Emerging evidence suggests cellular senescence, as a consequence of excess DNA damage and deficient repair, to be a driver of brain dysfunction following repeated mild traumatic brain injury (rmTBI). This study aimed to further investigate the role of deficient DNA repair, specifically BRCA1-related repair, on DNA damage-induced senescence. BRCA1, a repair protein involved in maintaining genomic integrity with multiple roles in the central nervous system, was previously reported to be significantly downregulated in post-mortem brains with a history of rmTBI. Here we examined the effects of impaired BRCA1-related repair on DNA damage-induced senescence and outcomes 1-week post-rmTBI using mice with a heterozygous knockout for BRCA1 in a sex-segregated manner. Altered BRCA1 repair with rmTBI resulted in altered anxiety-related behaviours in males and females using elevated zero maze and contextual fear conditioning. Evaluating molecular markers associated with DNA damage signalling and senescence-related pathways revealed sex-specific differences attributed to BRCA1, where females exhibited elevated DNA damage, impaired DNA damage signalling, and dampened senescence onset compared to males. Overall, the results from this study highlight sex-specific consequences of aberrant DNA repair on outcomes post-injury, and further support a need to develop sex-specific treatments following rmTBI.

The growing gap: A study of sleep, encoding, and consolidation of new words in chronic traumatic brain injury

Word learning is an iterative and dynamic process supported by multiple neural and cognitive systems. Converging evidence from behavioral, cellular, and systems neuroscience highlights sleep as an important support for memory and word learning over time. In many lab-based word learning experiments, participants encode and subsequently retrieve newly learned words in a single session. These designs are inadequate to capture the full dynamic word learning process, making them less ecologically valid. Single timepoint studies also limit investigation of the role of behavioral and lifestyle factors, like sleep, in supporting word learning over time. Adults with a history of traumatic brain injury (TBI), who commonly exhibit deficits in the memory systems that support word learning and report concomitant sleep disturbance, provide a unique opportunity to examine the link between memory, sleep, and word learning. Here we examined word learning over time and the influence of sleep on short- and long-term word recall in 50 adults with chronic moderate-severe TBI and 50 demographically matched neurotypical peers. We used a randomized within-participant crossover design to assess immediate encoding of new words and the consolidation of those words over time across intervals that did or did not involve sleep. Participants completed this study over the course of two weeks in their own homes to capture the iterative, dynamic process of real-world word learning. We also measured sleep in free living conditions using actigraphy throughout the experiment. Participants with TBI exhibited a word learning deficit that began at encoding and persisted across time. Critically, this deficit grew over the course of the week. The performance gap between groups was larger at the 1-week post-test than the immediate post-test, suggesting deficits in both encoding and consolidation of new words in individuals with TBI. Participants with and without TBI remembered more words when they slept after learning. Ecologically valid research designs that examine the relationship between memory, sleep, and word learning over time promise to advance mechanistic accounts of word learning and improve the long-term retention of new words in individuals with and without brain injury.

The effect of thioredoxin-1 in a rat model of traumatic brain injury depending on diurnal variation

INTRODUCTION

Traumatic brain injury (TBI) is a public health concern with limited treatment options because it causes a cascade of side effects that are the leading cause of hospital death. Thioredoxin is an enzyme with neuroprotective properties such as antioxidant, antiapoptotic, immune response modulator, and neurogenic, among others; it has been considered a therapeutic target for treating many disorders.

METHODS

The controlled cortical impact (CCI) model was used to assess the effect of recombinant human thioredoxin 1 (rhTrx1) (1 μg/2 μL, intracortical) on rats subjected to TBI at two different times of the light-dark cycle (01:00 and 13:00 h). We analyzed the food intake, body weight loss, motor coordination, pain perception, and histology in specific hippocampus (CA1, CA2, CA3, and Dental Gyrus) and striatum (caudate-putamen) areas.

RESULTS

Body weight loss, reduced food intake, spontaneous pain, motor impairment, and neuronal damage in specific hippocampus and striatum regions are more evident in rats subjected to TBI in the light phase than in the dark phase of the cycle and in groups that did not receive rhTrx1 or minocycline (as positive control). Three days after TBI, there is a recovery in body weight, food intake, motor impairment, and pain, which is more pronounced in the rats subjected to TBI at the dark phase of the cycle and those that received rhTrx1 or minocycline.

CONCLUSIONS

Knowing the time of day a TBI occurs in connection to the neuroprotective mechanisms of the immune response in diurnal variation and the usage of the Trx1 protein might have a beneficial therapeutic impact in promoting quick recovery after a TBI.

Home-Based Measurements of Nocturnal Cardiac Parasympathetic Activity in Athletes during Return to Sport after Sport-Related Concussion

Sport-related concussions (SRC) are characterized by impaired autonomic control. Heart rate variability (HRV) offers easily obtainable diagnostic approaches to SRC-associated dysautonomia, but studies investigating HRV during sleep, a crucial time for post-traumatic cerebral regeneration, are relatively sparse. The aim of this study was to assess nocturnal HRV in athletes during their return to sports (RTS) after SRC in their home environment using wireless wrist sensors (E4, Empatica, Milan, Italy) and to explore possible relations with clinical concussion-associated sleep symptoms. Eighteen SRC athletes wore a wrist sensor obtaining photoplethysmographic data at night during RTS as well as one night after full clinical recovery post RTS (>3 weeks). Nocturnal heart rate and parasympathetic activity of HRV (RMSSD) were calculated and compared using the Mann-Whitney U Test to values of eighteen; matched by sex, age, sport, and expertise, control athletes underwent the identical protocol. During RTS, nocturnal RMSSD of SRC athletes (Mdn = 77.74 ms) showed a trend compared to controls (Mdn = 95.68 ms, p = 0.021, r = -0.382, p adjusted using false discovery rate = 0.126) and positively correlated to "drowsiness" (r = 0.523, p = 0.023, p adjusted = 0.046). Post RTS, no differences in RMSSD between groups were detected. The presented findings in nocturnal cardiac parasympathetic activity during nights of RTS in SRC athletes might be a result of concussion, although its relation to recovery still needs to be elucidated. Utilization of wireless sensors and wearable technologies in home-based settings offer a possibility to obtain helpful objective data in the management of SRC.

Gender Specificities in Sleep Disturbances following Mild Traumatic Brain Injury: A Preliminary Study

Mild traumatic brain injury (mTBI), or concussion, can lead to persistent cognitive and functional symptoms that impede quality of life to a varying extent. This condition is referred to as post-concussive syndrome (PCS). Sleep disturbances are part of it but their distribution among different genders remains scarcely investigated. This pilot cross-sectional anonymous web-based survey interviewed volunteer 18-55 years old participants with a recent (i.e., less than 5 years) reported history of mTBI. Questionnaires related to persistent post-concussive symptoms (PPCS; Rivermead post-concussion symptoms questionnaire), sleep quality (Pittsburgh Sleep Quality Index) and daytime sleepiness (Epworth Sleepiness Scale) were administered as part of the survey. Ninety-one participants' responses were analysed (61 female; 30 male); 43% of them suffered from post-concussive syndrome, 60% reported poor sleep quality and 34% experienced excessive daytime sleepiness. The proportion of PPCS was significantly higher in female participants as compared to males (female: 57%; male: 13%; Fisher's exact test p < 0.001). Excessive daytime sleepiness was also significantly more present in females (female: 44%; male: 13%; p < 0.001) whereas poor sleep quality was present in similar proportions between females and males (female: 66%; male: 50%; p = 0.176). Even though based on a relatively small sample, these findings highlight important gender differences that should be accounted for in PPCS medical care and management.

Sex predicts post-concussion symptom reporting, independently of fatigue and subjective sleep disturbance, in premorbidly healthy adults after mild traumatic brain injury

The relationship between sex and post-concussion symptom (PCS) reporting after mild traumatic brain injury (mTBI) is not well understood. Subjective sleep disturbance and fatigue impact PCS reporting after mTBI and show sex differences in the normal population. This study investigated whether sex had a relationship with PCS reporting after mTBI, independently of self-reported sleep disturbance and fatigue. Ninety-two premorbidly healthy adults in the post-acute period after mTBI completed the Rivermead Post-Concussion Symptoms Questionnaire, the Pittsburgh Sleep Quality Index, the Multidimensional Fatigue Inventory and measures of depression, anxiety and post-traumatic stress symptomatology. Females (n = 23) demonstrated higher levels of fatigue (p = .019) and greater psychological distress (p = .001) than males (n = 69), but equivalent levels of sleep disturbance (p = .946). Bootstrapping analyses were undertaken because PCS responses were not normally distributed. Female sex predicted greater PCS reporting (p = .001), independently of subjective sleep disturbance, fatigue, psychological distress and litigation status. The current findings support and extend previous work showing premorbidly healthy females are at higher risk of experiencing elevated PCS after mTBI than males in the post-acute period after mTBI. It may be beneficial for clinicians to be particularly sensitive to increased symptom reporting after mTBI in females, irrespective of sleep quality, fatigue or psychological status.

Circadian Rhythmicity of Vital Signs at Intensive Care Unit Discharge and Outcome of Traumatic Brain Injury

BACKGROUND

Physiological functions with circadian rhythmicity are often disrupted during illness.

OBJECTIVE

To assess the utility of circadian rhythmicity of vital signs in predicting outcome of traumatic brain injury (TBI).

METHODS

A retrospective single-center cohort study of adult intensive care unit (ICU) patients with largely isolated TBI to explore the relationship between the circadian rhythmicity of vital signs during the last 24 hours before ICU discharge and clinical markers of TBI severity and score on the Glasgow Outcome Scale 6 months after injury (GOS-6).

RESULTS

The 130 study participants had a median age of 39.0 years (IQR, 23.0-59.0 years), a median Glasgow Coma Scale score at the scene of 8.0 (IQR, 3.0-13.0), and a median Rotterdam score on computed tomography of the head of 3 (IQR, 3-3), with 105 patients (80.8%) surviving to hospital discharge. Rhythmicity was present for heart rate (30.8% of patients), systolic blood pressure (26.2%), diastolic blood pressure (20.0%), and body temperature (26.9%). Independent predictors of a dichotomized GOS-6 ≥4 were the Rotterdam score (odds ratio [OR], 0.38 [95% CI, 0.18-0.81]; P = .01), Glasgow Coma Scale score at the scene (OR, 1.22 [95% CI, 1.05-1.41]; P = .008), age (OR, 0.95 [95% CI, 0.92-0.98]; P = .003), oxygen saturation <90% in the first 24 hours (OR, 0.19 [95% CI, 0.05-0.73]; P = .02), serum sodium level <130 mmol/L (OR, 0.20 [95% CI, 0.05-0.70]; P = .01), and active intracranial pressure management (OR, 0.16 [95% CI, 0.04-0.62]; P = .008), but not rhythmicity of any vital sign.

CONCLUSION

Circadian rhythmicity of vital signs at ICU discharge is not predictive of GOS-6 in patients with TBI.

Efficacy and acceptability of blue-wavelength light therapy for post-TBI behavioral symptoms: A systematic review and meta-analysis of randomized controlled trials

Objective

Behavioral symptoms are common after traumatic brain injury (TBI), but their treatments remain unsatisfactory. This systematic review and meta-analysis compared the efficacy and acceptability between blue-wavelength light therapy (BWLT) and long-wavelength/no light therapy (LW/NLT) for post-TBI sleepiness, sleep disturbance, depressive symptoms, and fatigue.

Methods

This study included randomized controlled trials comparing the effects of BWLT and LW/NLT on post-TBI sleepiness, sleep disturbance, depression, or fatigue. We searched Pubmed, Embase, CINAHL, and Cochrane Central Register of Controlled of Trials on April 13, 2022. The revised tool for assessing the risk of bias in randomized trials was applied. We performed a frequentist pairwise meta-analysis using a random-effects model.

Results

Of 233 retrieved records, six trials (N = 278) were included in this meta-analysis. TBIs ranged from mild to severe, and the interventions were administered for a median of 35 days. Most trials delivered light therapy via lightboxes. Three trials had a high risk of bias. BWLT was significantly superior to LW/NLT in reducing sleep disturbance (5 trials; SMD = -0.63; 95% CI = -1.21 to -0.05; p = 0.03; I² = 61%) and depressive symptoms (4 trials; SMD = -1.00; 95% CI = -1.62 to -0.38; p < 0.01; I² = 56%). There were trends that BWLT was superior to LW/NLT in reducing sleepiness (6 trials; SMD = -0.92; 95% CI = -1.84 to 0.00; p = 0.05; I² = 88%) and fatigue (4 trials; SMD = -1.44; 95% CI = -2.95 to 0.08; p = 0.06; I² = 91%). All-cause dropout rates were not significantly different between groups.

Conclusion

Limited and heterogenous evidence suggests that short-term BWLT is well accepted, has a large treatment effect on post-TBI depressive symptoms, and may have a moderate treatment effect on post-TBI sleep disturbance.

ASSOCIATION BETWEEN ALTERED CORTISOL PROFILES AND NEUROBEHAVIORAL IMPAIRMENT FOLLOWING mTBI IN COLLEGE STUDENTS

Mild Traumatic Brain Injury (mTBI) is the most common form of TBI, accounting for over 2.5 million TBI cases in the United States annually. Identification of easily obtainable biomarkers that track strongly with mTBI symptoms may improve our understanding of biological factors that contribute to mTBI symptom profiles and long-term outcomes. Notably, some individuals with mTBI exhibit circadian disruptions and elevated stress sensitivity, which in other clinical groups often correlate with disrupted secretion of cortisol, a glucocorticoid hormone that coordinates circadian and stress physiology. Here, we sought to determine whether cortisol profiles could serve as a biomarker to complement the assessment of neurobehavioral sequelae following mTBI. We partnered with our on-campus health clinic to recruit college students seeking medical care following mTBI (n=46) and compared this population to a well-matched non-injured student control group (n=44). We collected data at an initial visit (shortly after injury in mTBI subjects) and one week later. At each visit, we evaluated neurobehavioral function using the Automated Neuropsychological Assessment Metric (ANAM). Our subjects then provided cortisol samples through at-home saliva collection. We observed strong coherence between ANAM subjective and objective measures, indicating significant multidimensional impairment in those with mTBI. Further, female mTBI subjects exhibited diminished neurobehavioral function compared to males. Regardless of sex, decreased amplitude of diurnal cortisol and a blunted cortisol awakening response predicted mTBI symptom severity and neurobehavioral impairment. Taken together, these findings suggest that salivary cortisol profiles may be a sensitive biomarker for studying underlying biological factors that impact mTBI outcomes.

Poor Sleep Quality is Linked to Elevated Extracellular Vesicle-Associated Inflammatory Cytokines in Warfighters With Chronic Mild Traumatic Brain Injuries

Background: Elevations of inflammatory cytokine levels occur immediately after mild traumatic brain injury (mTBI) and can persist for years. These elevations have been associated with neuropsychological outcomes, including depression and PTSD symptoms. Sleep disorders, another common sequelae of mTBI, are independently associated with inflammation in otherwise healthy individuals. However, whether sleep and inflammation are linked in chronic mTBI has not been reported.

Methods: A retrospective cross-sectional cohort of warfighters was used to investigate the hypothesis that inflammation may be linked to sleep quality in chronic mTBI. Clinical history, peripheral blood samples, and sleep quality scores were collected from 182 warfighters (n = 138 mTBI; n = 44 controls) during enrollment in the Chronic Effects of Neurotrauma Consortium study. Biomarkers of inflammation (IL-6, IL-10, TNFα cytokines) from plasma and plasma-derived extracellular vesicles (EVs) were quantified using single molecule array. Relationships between sleep quality and cytokine levels were assessed, controlling for age, sex, and BMI. Using clinical cutoff scores for sleep quality, mTBI patients were then divided into “good” and “poor” sleepers and cytokine levels compared between groups.

Results: In mTBI participants, sleep quality was significantly associated with EV levels of IL-10 [ß (SE) = 0.11 (0.04), p = 0.01] and TNFα [ß (SE) = 0.07 (0.03), p < 0.01]. When divided according to “good” versus “poor” sleepers, those reporting poor sleep had significantly elevated EV IL-10 compared to those reporting good sleep [ß (SE) = 0.12 (0.04), p < 0.01]. Plasma-derived associations were not significant. No associations were found between sleep quality and cytokine levels in controls.

Conclusion: These results suggest a significant relationship between sleep quality and chronic inflammation in mTBI patients. Clinically, mTBI patients with a high likelihood of sleep disorders demonstrate elevated levels of inflammatory cytokines. Signal from EVs, though smaller in magnitude, may have stronger clinical associations than from plasma. Sleep-focused interventions may also serve to regulate chronic inflammatory processes in these patients. Larger prospective studies are needed to investigate the mechanisms and therapeutic implications of the likely bi-directional relationship between sleep and inflammation following mTBI.

Trajectories of Insomnia in Adults After Traumatic Brain Injury

IMPORTANCE

Insomnia is common after traumatic brain injury (TBI) and contributes to morbidity and long-term sequelae.

OBJECTIVE

To identify unique trajectories of insomnia in the 12 months after TBI.

DESIGN, SETTING, AND PARTICIPANTS

In this prospective cohort study, latent class mixed models (LCMMs) were used to model insomnia trajectories over time and to classify participants into distinct profile groups. Data from the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study, a longitudinal, multisite, observational study, were uploaded to the Federal Interagency Traumatic Brain Injury Repository (FITBIR) database. Participants were enrolled at 1 of 18 participating level I trauma centers and enrolled within 24 hours of TBI injury. Additional data were obtained directly from the TRACK-TBI investigators that will be uploaded to FITBIR in the future. Data were collected from February 26, 2014, to August 8, 2018, and analyzed from July 1, 2020, to November 15, 2021.

EXPOSURES

Traumatic brain injury.

MAIN OUTCOMES AND MEASURES

Insomnia Severity Index assessed serially at 2 weeks and 3, 6, and 12 months thereafter.

RESULTS

The final sample included 2022 participants (1377 [68.1%] men; mean [SD] age, 40.1 [17.2] years) from the FITBIR database and the TRACK-TBI study. The data were best fit by a 5-class LCMM. Of these participants, 1245 (61.6%) reported persistent mild insomnia symptoms (class 1); 627 (31.0%) initially reported mild insomnia symptoms that resolved over time (class 2); 91 (4.5%) reported persistent severe insomnia symptoms (class 3); 44 (2.2%) initially reported severe insomnia symptoms that resolved by 12 months (class 4); and 15 (0.7%) initially reported no insomnia symptoms but had severe symptoms by 12 months (class 5). In a multinomial logistic regression model, several factors significantly associated with insomnia trajectory class membership were identified, including female sex (odds ratio [OR], 1.65 [95% CI, 1.02-2.66]), Black race (OR, 2.36 [95% CI, 1.39-4.01]), history of psychiatric illness (OR, 2.21 [95% CI, 1.35-3.60]), and findings consistent with intracranial injury on computed tomography (OR, 0.36 [95% CI, 0.20-0.65]) when comparing class 3 with class 1.

CONCLUSIONS AND RELEVANCE

These results suggest important heterogeneity in the course of insomnia after TBI in adults. More work is needed to identify outcomes associated with these insomnia trajectory class subgroups and to identify optimal subgroup-specific treatment approaches.

A novel mechanism linking ferroptosis and endoplasmic reticulum stress via the circPtpn14/miR-351-5p/5-LOX signaling in melatonin-mediated treatment of traumatic brain injury

Traumatic brain injury (TBI) can lead to disability or devastating consequences with few established treatments. Although ferroptosis has been shown to be involved in TBI, the underlying mechanism was rarely known. Melatonin has been indicated to exhibit neuroprotective activities. However, the anti-ferroptotic effects of melatonin on TBI have not yet to be elucidated. We aimed to investigate whether ferroptosis was induced in humans after TBI and whether ferroptosis inhibition by melatonin could protect against blood-brain barrier (BBB) damage after TBI in vivo and in vitro. Circular RNAs (circRNAs) are highly expressed in the brain. For the first time, differentially expressed circRNA after melatonin treatment for TBI were detected by RNA sequencing. We found that lipid peroxidation was induced in humans after TBI, while melatonin significantly improved brain function of mice after TBI and alleviated ferroptosis and endoplasmic reticulum (ER) stress in vivo and in vitro. A total of 1826 differentially expressed circRNAs were found (fold change >2, Q < 0.01), including 921 down-regulated and 905 up-regulated circRNAs in the injured brain tissues of TBI mice receiving melatonin treatment. Mechanistically, melatonin administration reduced the level of circPtpn14 (mmu_circ_0000130), which functioned by acting as a miR-351-5p sponge to positively regulate the expression of the ferroptosis-related 5-lipoxygenase (5-LOX). Moreover, circPtpn14 overexpression partly abolished the inhibitory effects of melatonin on ferroptosis. Collectively, our findings provide the first evidence that melatonin could exert anti-ferroptotic and anti-ER stress effects in brain injury by alleviating lipid peroxidation via the circPtpn14/miR-351-5p/5-LOX signaling.

Adolescent sleep health and school start times: Setting the research agenda for California and beyond: A research summit summary: A research summit summary

In fall 2019, California passed and signed into law SB328, the first US statewide legislation explicitly designed to protect adolescent sleep health by requiring most California public school districts to start no earlier than 8:00 AM for middle schools and 8:30 AM for high schools. Recognizing the unique opportunity presented by the bill's 3-year implementation period, a group of experts in adolescent sleep and school start times held a virtual summit on January 22-23, 2021 to (1) summarize the research on adolescent sleep and school start time change; (2) develop recommendations for relevant, refined, and innovative research areas and research questions; (3) provide input regarding research design, methodology, and implementation; and (4) offer a forum for networking, exchanging ideas, and establishing interdisciplinary research collaborations. Participants represented a multidisciplinary range of academic backgrounds including sleep and circadian biology, neuroscience, education, medicine, public health, mental health, safety, public policy, economics, implementation science, criminology, diversity studies, and science communication. This paper summarizes summit presentations regarding current knowledge on adolescent sleep health and school start times and key research recommendations from small group workshops on topics including research design and tools, methodological issues, sleep health disparities, logistical challenges in conducting school-based research, public-health impact, and novel and expanded approaches to research.

Characterizing Sleep and Wakefulness in the Acute Phase of Concussion in the General Population: A Naturalistic Cohort from the Toronto Concussion Study

Growing literature links concussion to changes in sleep and wakefulness in humans and in rodent models. Sleep has been linked with synaptic reorganization under other conditions; however, the characterization and role of sleep after acute concussion remains poorly understood. While much research has focused on insomnia among patients with chronic or persistent concussion symptoms, there is limited understanding of sleep and acute concussion, its potential role in recovery, and associated risk factors for the development of chronic sleep disturbance. Studies to date are limited by small sample sizes of primarily athlete or military populations. Additional studies among the general population are critical to inform best practice guidelines. We examined the sleep and daytime wakefulness of 472 adults from a naturalistic general population cohort (mean age, 33.3 years, females = 60.8%) within seven days of diagnosed concussion, using a validated, condition-specific measure, the Sleep and Concussion Questionnaire. Participants identified immediate changes in sleep characterized by hypersomnia and difficulty maintaining daytime wakefulness; 35% considered these changes as moderate to severe and 79% required monitoring or follow-up. Females experienced significantly greater severity of changes in sleep compared with males. Positive correlations between severity of sleep and pain and headache were identified. Differences by sex are an important consideration for early intervention and long-term monitoring. Because sleep was compromised by pain, pain management is also an integral part of early intervention. Our findings suggest that assessment of sleep beginning in the acute stage is a critical component of concussion management in the general population.

Prevalence of insomnia and insomnia symptoms following mild-traumatic brain injury: A systematic review and meta-analysis

Sleep is commonly disrupted following mild traumatic brain injury (mTBI), however there is a lack of consensus in the existing literature regarding the prevalence of insomnia/insomnia symptoms after injury. The aim of this review was to conduct a systematic review and meta-analysis of insomnia and insomnia symptoms' prevalence following mTBI. Full-text articles published in English in peer-reviewed journals, including adults with a clinical or self-reported mild traumatic brain injury diagnosis, were eligible for inclusion. Studies that assessed insomnia/insomnia symptoms after injury were included. Of the 2091 records identified, 20 studies were included in the review. 19 of these were meta-analysed (n = 95,195), indicating high heterogeneity among studies. Subgroup analyses indicated pooled prevalence estimates of post-mTBI insomnia disorder of 27.0% (95% CI 6.49-54.68) and insomnia symptoms of 71.7% (95% CI 60.31-81.85). The prevalence of insomnia is significantly higher in individuals who have sustained mild traumatic brain injury compared to prevalence estimates reported in the general population but high heterogeneity and methodological differences among studies make it difficult to provide reliable prevalence estimates. Future research should continue to advance our understanding of the onset, progression and impact of post-mild traumatic brain injury insomnia to promote the recovery and wellbeing of affected individuals. PROSPERO registration CRD42020168563.

Pharmacotherapy to prevent the onset of depression following traumatic brain injury

INTRODUCTION

Depressive symptoms may follow traumatic brain injury (TBI), affecting cognition, apathy, and overall general functioning. Pharmacotherapy to prevent the onset of depression following TBI is, therefore, crucial.

AREAS COVERED

The present report critically appraises current pharmacotherapy to prevent the onset of depression following TBI as well as novel potential pharmacological avenues on the matter. Both efficacy and safety issues are considered, emphasizing an evidence-based approach whenever feasible. The authors further provide the reader with their expert opinion and future perspectives on the subject.

EXPERT OPINION

Despite its clinical burden and relatively frequent occurrence, the prophylaxis of post-TBI depression warrants further research. The current clinical guidelines of depression do not account for people with a primary diagnosis of TBI. Prospective cohort studies supported by proof-of-concept trials are nonetheless urged toward more effective, patient-tailored pharmacotherapy to prevent the onset of depression and treatment-resistance phenomena following TBI.

Current Alzheimer disease research highlights: evidence for novel risk factors

Alzheimer disease (AD) is the most common type of dementia characterized by the progressive cognitive and social decline. Clinical drug targets have heavily focused on the amyloid hypothesis, with amyloid beta (Aβ), and tau proteins as key pathophysiologic markers of AD. However, no effective treatment has been developed so far, which prompts researchers to focus on other aspects of AD beyond Aβ, and tau proteins. Additionally, there is a mounting epidemiologic evidence that various environmental factors influence the development of dementia and that dementia etiology is likely heterogenous. In the past decades, new risk factors or potential etiologies have been widely studied. Here, we review several novel epidemiologic and clinical research developments that focus on sleep, hypoxia, diet, gut microbiota, and hearing impairment and their links to AD published in recent years. At the frontiers of AD research, these findings and updates could be worthy of further attention.

Review of wearable technologies and machine learning methodologies for systematic detection of mild traumatic brain injuries

Mild traumatic brain injuries (mTBIs) are the most common type of brain injury. Timely diagnosis of mTBI is crucial in making 'go/no-go' decision in order to prevent repeated injury, avoid strenuous activities which may prolong recovery, and assure capabilities of high-level performance of the subject. If undiagnosed, mTBI may lead to various short- and long-term abnormalities, which include, but are not limited to impaired cognitive function, fatigue, depression, irritability, and headaches. Existing screening and diagnostic tools to detect acute andearly-stagemTBIs have insufficient sensitivity and specificity. This results in uncertainty in clinical decision-making regarding diagnosis and returning to activity or requiring further medical treatment. Therefore, it is important to identify relevant physiological biomarkers that can be integrated into a mutually complementary set and provide a combination of data modalities for improved on-site diagnostic sensitivity of mTBI. In recent years, the processing power, signal fidelity, and the number of recording channels and modalities of wearable healthcare devices have improved tremendously and generated an enormous amount of data. During the same period, there have been incredible advances in machine learning tools and data processing methodologies. These achievements are enabling clinicians and engineers to develop and implement multiparametric high-precision diagnostic tools for mTBI. In this review, we first assess clinical challenges in the diagnosis of acute mTBI, and then consider recording modalities and hardware implementation of various sensing technologies used to assess physiological biomarkers that may be related to mTBI. Finally, we discuss the state of the art in machine learning-based detection of mTBI and consider how a more diverse list of quantitative physiological biomarker features may improve current data-driven approaches in providing mTBI patients timely diagnosis and treatment.

Characterizing Physical Activity and Sedentary Behavior in Adults With Persistent Postconcussive Symptoms After Mild Traumatic Brain Injury

OBJECTIVE

To evaluate physical activity (PA) and sedentary behavior and their associations with symptom and quality of life outcomes in adults with persistent postconcussive symptoms (PPCS) after mild traumatic brain injury (mTBI).

DESIGN

Cross-sectional cohort study.

SETTING

Outpatient brain injury clinic.

PARTICIPANTS

Consecutive sample of adults (N=180) with a diagnosis of mTBI and PPCS.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

PA and sedentary behavior were assessed using the Godin Leisure-Time Exercise Questionnaire and Rapid Assessment Disuse Index, respectively. Participants were dichotomized according to whether they completed 150 minutes of moderate-to-vigorous PA per week, based on Canadian guidelines. Postinjury moderate-to-vigorous PA was also analyzed as a continuous variable.

RESULTS

Prior to injury, 85% of participants reported meeting PA guidelines, compared with 28% postinjury. Individuals meeting PA guidelines postinjury reported higher quality of life (η²_p=0.130; P<.001) and lower scores on measures of functional impact of headache (η²_p=0.065; P=.009), fatigue (η²_p=0.080; P=.004), depression (η²_p=0.085; P=.001), and anxiety (η²_p=0.046; P=.031), compared with those not meeting guidelines. Sedentary behavior postinjury was negatively correlated with quality of life (r_s[127]=-0.252; P=.004) and positively correlated with symptom burden (r_s[167]=0.227; P=.003), fatigue (r_s[127]=0.288; P=.001), depression (r_s[174]=0.319; P<.001), and anxiety (r_s[127]=0.180; P=.042).

CONCLUSIONS

PA was significantly decreased in individuals with PPCS compared to preinjury levels. Meeting PA guidelines postinjury was associated with better clinical outcomes, suggesting that returning individuals to PA should be considered in the treatment of this patient population.

Traumatic Brain Injury and Incidence Risk of Sleep Disorders in Nearly 200,000 US Veterans

OBJECTIVE

To test the hypothesis that veterans with traumatic brain injury (TBI) have an increased subsequent risk of sleep disorders, we studied the longitudinal association between TBI and incident sleep disorders in nearly 200,000 veterans.

METHODS

We performed a cohort study of all patients diagnosed with a TBI in the Veterans Health Administration system from October 1, 2001, to September 30, 2015, who were age-matched 1:1 to veterans without TBI. Veterans with prevalent sleep disorders at baseline were excluded. Development of sleep disorders was defined as any inpatient or outpatient diagnosis of sleep apnea, hypersomnia, insomnia, or sleep-related movement disorders based on ICD-9 codes after the first TBI diagnosis or the random selection date for those without TBI. We restricted the analysis to those with at least 1 year of follow-up. We used Cox proportional hazards models to examine the association between TBI and subsequent risk of sleep disorders.

RESULTS

The study included 98,709 veterans with TBI and 98,709 age-matched veterans without TBI (age 49 ± 20 years). After an average follow-up of 5 (1-14) years, 23,127 (19.6%) veterans developed sleep disorders. After adjustment for demographics, education, income, and medical and psychiatric conditions, those who had TBI compared to those without TBI were 41% more likely to develop any sleep disorders (hazard ratio 1.41 [95% confidence interval 1.37-1.44]), including sleep apnea (1.28 [1.24-1.32]), insomnia (1.50 [1.45-1.55]), hypersomnia (1.50 [1.39-1.61]), and sleep-related movement disorders (1.33 [1.16-1.52]). The association was stronger for mild TBIs, did not differ appreciably by presence of posttraumatic stress disorder, and remained after a 2-year time lag.

CONCLUSION

In 197,418 veterans without sleep disorders, those with diagnosed TBI had an increased risk of incident sleep disorders over 14 years. Improved prevention and long-term management strategies for sleep are needed for veterans with TBI.

Therapeutic benefits of pharmacologic and nonpharmacologic treatments for depressive symptoms after traumatic brain injury: a systematic review and network meta-analysis

BACKGROUND

Depression is a common morbidity after traumatic brain injury. This network meta-analysis investigated the efficacy and tolerability of pharmacologic and nonpharmacologic interventions for depression after traumatic brain injury.

METHODS

We extracted randomized controlled trials examining pharmacologic or nonpharmacologic interventions with placebo- or active-controlled designs from PubMed, the Cochrane Library and ScienceDirect, from inception to October 30, 2018. We based study selection and extraction of a predefined list of variables on the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, and conducted meta-analysis procedures using random effects modelling. Primary outcomes were changes in depressive symptom severity after pharmacologic or nonpharmacologic treatment; the secondary outcome was tolerability, reflected in overall patient dropout rates.

RESULTS

Our analysis of 27 randomized controlled trials (10 pharmacologic, total n = 483, mean age = 37.9 yr; 17 nonpharmacologic, total n = 1083, mean age = 38.0 yr) showed that methylphenidate had significantly superior efficacy compared to placebo or control (standardized mean difference -0.91, 95% confidence interval [CI] -1.49 to -0.33). Sertraline was associated with significantly lower tolerability (i.e., a higher dropout rate) compared to placebo or control (odds ratio 2.65, 95% CI 1.27 to 5.54). No nonpharmacologic treatment was more effective than the others, and we found no significant differences in tolerability (i.e., dropout rates) among the nonpharmacologic treatments.

LIMITATIONS

Heterogeneity in participant characteristics (e.g., comorbidities), study designs (e.g., trial duration) and psychopathology assessment tools, as well as small trial numbers for some treatment arms, could have been confounders.

CONCLUSION

The present network meta-analysis suggests that methylphenidate might be the best pharmacologic intervention for depressive symptoms related to traumatic brain injury. None of the nonpharmacologic interventions was associated with better improvement in depressive symptoms than the others or than control conditions. None of the pharmacologic or nonpharmacologic treatments had inferior tolerability compared to placebo or controls except for sertraline, which had significantly lower tolerability than placebo.

Health Phenotypes and Neurobehavioral Symptom Severity Among Post-9/11 Veterans With Mild Traumatic Brain Injury: A Chronic Effects of Neurotrauma Consortium Study

OBJECTIVE

To evaluate whether neurobehavioral symptoms differ between groups of veterans with mild traumatic brain injury (mTBI) classified by health characteristics.

PARTICIPANTS

A total of 71 934 post-9/11 veterans with mTBI from the Chronic Effects of Neurotrauma Consortium Epidemiology warfighter cohort.

DESIGN

Cross-sectional analysis of retrospective cohort.

MAIN MEASURES

Health phenotypes identified using latent class analysis of health and function over 5 years. Symptom severity measured using Neurobehavioral Symptom Inventory; domains included vestibular, somatic, cognitive, and affective.

RESULTS

Veterans classified as moderately healthy had the lowest symptom burden while the polytrauma phenotype group had the highest. After accounting for sociodemographic and injury characteristics, polytrauma phenotype veterans had about 3 times the odds of reporting severe symptoms in each domain compared with moderately healthy veterans. Those veterans who were initially moderately healthy but whose health declined over time had about twice the odds of severe symptoms as consistently healthier Veterans. The strongest associations were in the affective domain. Compared with the moderately healthy group, veterans in other phenotypes were more likely to report symptoms substantially interfered with their daily lives (odds ratio range: 1.3-2.8).

CONCLUSION

Symptom severity and interference varied by phenotype, including between veterans with stable and declining health. Ameliorating severe symptoms, particularly in the affective domain, could improve health trajectories following mTBI.

The Prevalence and Stability of Sleep-Wake Disturbance and Fatigue throughout the First Year after Mild Traumatic Brain Injury

In this prospective, longitudinal study, we aimed to determine the prevalence and stability of sleep-wake disturbance (SWD) and fatigue in a large representative sample of patients (Trondheim mild traumatic brain injury [mTBI] follow-up study). We included 378 patients with mTBI (age 16-60), 82 matched trauma controls with orthopedic injuries, and 83 matched community controls. Increased sleep need, poor sleep quality, excessive daytime sleepiness, and fatigue were assessed at 2 weeks, 3 months, and 12 months after injury. Mixed logistic regression models were used to evaluate clinically relevant group differences longitudinally. Prevalence of increased sleep need, poor sleep quality, and fatigue was significantly higher in patients with mTBI than in both trauma controls and community controls at all time points. More patients with mTBI reported problems with excessive daytime sleepiness compared to trauma controls, but not community controls, at all time points. Patients with complicated mTBI (intracranial findings on computed tomography or magnetic resonance imaging) had more fatigue problems compared to those with uncomplicated mTBI, at all three time points. In patients with mTBI who experienced SWDs and fatigue 2 weeks after injury, around half still had problems at 3 months and approximately one third at 12 months. Interestingly, we observed limited overlap between the different symptom measures; a large number of patients reported one specific problem with SWD or fatigue rather than several problems. In conclusion, our results provide strong evidence that mTBI contributes significantly to the development and maintenance of SWDs and fatigue.

Treatment of Depression after Traumatic Brain Injury Reduces Risk of Neuropsychiatric Outcomes

The objectives of this study were to identify characteristics associated with receipt of antidepressants for treatment of incident depression diagnosed following traumatic brain injury (TBI) and to assess the impact of receipt of treatment for depression on risk of other neuropsychiatric outcomes associated with TBI. We conducted a retrospective cohort study of individuals with TBI who were subsequently diagnosed with incident depression between 2008 and 2014 using data from the OptumLabs® Data Warehouse. We identified factors associated with receipt of antidepressants and compared risk of new diagnosis of alcohol dependence disorder, anxiety, insomnia, and substance dependence disorder between those who received antidepressants and those who did not over a maximum 2-year follow-up, controlling for duration of use and clinical and demographic characteristics. Of 9581 individuals newly diagnosed with depression following TBI, 4103 (43%) received at least one antidepressant. Moderate-severe TBI (odds ratio [OR] 1.44; 95% confidence interval [CI]: 1.39, 1.50), female sex (OR 1.21; 95% CI: 1.19, 1.24), diagnosis of Alzheimer's disease (OR 1.39; 95% CI: 1.35, 1.44), and anxiety (OR 1.35; 95% CI: 1.31, 1.38) were associated with receipt of antidepressants. Longer duration of antidepressant use was associated with decreased risk of newly diagnosed anxiety (hazard ratio [HR] 0.92; 95% CI: 0.89, 0.96), insomnia (HR 0.94; 95% CI: 0.91, 0.98), and substance dependence disorder (HR 0.92; 95% CI: 0.88, 0.97). These results provide evidence of a beneficial effect of antidepressant use on incidence of outcomes associated with poorer recovery from TBI.

The Molecular Pathophysiology of Concussion

After a concussion, a series of complex, overlapping, and disruptive events occur within the brain, leading to symptoms and behavioral dysfunction. These events include ionic shifts, damaged neuronal architecture, higher concentrations of inflammatory chemicals, increased excitatory neurotransmitter release, and cerebral blood flow disruptions, leading to a neuronal crisis. This review summarizes the translational aspects of the pathophysiologic cascade of postconcussion events, focusing on the role of excitatory neurotransmitters and ionic fluxes, and their role in neuronal disruption. We review the relationship between physiologic disruption and behavioral alterations, and proposed treatments aimed to restore the balance of disrupted processes.

Concussive head injury exacerbates neuropathology of sleep deprivation: Superior neuroprotection by co-administration of TiO2-nanowired cerebrolysin, alpha-melanocyte-stimulating hormone, and mesenchymal stem cells

Sleep deprivation (SD) is common in military personnel engaged in combat operations leading to brain dysfunction. Military personnel during acute or chronic SD often prone to traumatic brain injury (TBI) indicating the possibility of further exacerbating brain pathology. Several lines of evidence suggest that in both TBI and SD alpha-melanocyte-stimulating hormone (α-MSH) and brain-derived neurotrophic factor (BDNF) levels decreases in plasma and brain. Thus, a possibility exists that exogenous supplement of α-MSH and/or BDNF induces neuroprotection in SD compounded with TBI. In addition, mesenchymal stem cells (MSCs) are very portent in inducing neuroprotection in TBI. We examined the effects of concussive head injury (CHI) in SD on brain pathology. Furthermore, possible neuroprotective effects of α-MSH, MSCs and neurotrophic factors treatment were explored in a rat model of SD and CHI. Rats subjected to 48h SD with CHI exhibited higher leakage of BBB to Evans blue and radioiodine compared to identical SD or CHI alone. Brain pathology was also exacerbated in SD with CHI group as compared to SD or CHI alone together with a significant reduction in α-MSH and BDNF levels in plasma and brain and enhanced level of tumor necrosis factor-alpha (TNF-α). Exogenous administration of α-MSH (250μg/kg) together with MSCs (1×10⁶) and cerebrolysin (a balanced composition of several neurotrophic factors and active peptide fragments) (5mL/kg) significantly induced neuroprotection in SD with CHI. Interestingly, TiO₂ nanowired delivery of α-MSH (100μg), MSCs, and cerebrolysin (2.5mL/kg) induced enhanced neuroprotection with higher levels of α-MSH and BDNF and decreased the TNF-α in SD with CHI. These observations are the first to show that TiO₂ nanowired administration of α-MSH, MSCs and cerebrolysin induces superior neuroprotection following SD in CHI, not reported earlier. The clinical significance of our findings in light of the current literature is discussed.

Perspective: Cognitive Behavioral Therapy for Insomnia Is a Promising Intervention for Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is a significant public health problem. Insomnia is one of the most common symptoms of TBI, occurring in 30–50% of patients with TBI, and is more frequently reported in patients with mild as opposed to moderate or severe TBI. Although insomnia may be precipitated by mTBI, it is unlikely to subside on its own without specific treatment even after symptoms of mTBI reduce or remit. Insomnia is a novel, highly modifiable treatment target in mTBI, treatment of which has the potential to make broad positive impacts on the symptoms and recovery following brain injury. Cognitive-behavioral therapy for insomnia (CBT-I) is the front-line intervention for insomnia and has demonstrated effectiveness across clinical trials; between 70 and 80% of patients with insomnia experience enduring benefit from CBT-I and about 50% experience clinical remission. Examining an existing model of the development of insomnia in the context of mTBI suggests CBT-I may be effective for insomnia initiated or exacerbated by sustaining a mTBI, but this hypothesis has yet to be tested via clinical trial. Thus, more research supporting the use of CBT-I in special populations such as mTBI is warranted. The current paper provides a background on existing evidence for using CBT-I in the context of TBI, raises key challenges, and suggests considerations for future directions including need for increased screening and assessment of sleep disorders in the context of TBI, examining efficacy of CBT-I in TBI, and exploring factors that impact dissemination and delivery of CBT-I in TBI.