PERSONS with traumatic brain injury (TBI) demonstrate a greater prevalence of sleep disorders than the general population.1 Sleep disturbances and their sequelae after TBI have been investigated with methodologic limitations. Most studies to date have included convenience or selected samples, limiting our understanding of the true incidence of sleep problems or disorders after TBI.2-8 Studies are often cross-sectional with varying levels of or limited injury severity information, which limits understanding of the natural history of sleep problems after TBI.3,4 Using a clinician rating, severity of TBI and time-elapsed postinjury has been shown to interact with the presence and severity of sleep disturbance.9 Furthermore, level of functioning and comorbidities following TBI is dynamic and may interact with sleep disturbance and sleep methods under study.10,11 Another limitation is a paucity of research using objective sleep technologies.12-14 Studies examining sleep in the general population have found that self-report is often inconsistent with objective measures of sleep15,16 This problem is likely more prevalent in persons with TBI who often have cognitive and awareness impairments that further impact accuracy of sleep problems. Hospital-based studies using nursing logs that document eye closure/opening may not be a valid proxy for sleep.17 Finally, the lack of empirical data supporting sleep treatments in TBI has resulted in a polypharmacy approach to sleep management with potential untoward consequences.18 Empirically derived guidelines for evaluation and management of specific sleep disorders are made readily accessible by the American Academy of Sleep Medicine; however, their implementation in routine TBI clinical care is poorly understood.19 Without understanding the underlying cause, treatment of sleep symptoms may be futile. Improved characterization of sleep disturbances and disorders after TBI may help direct targeted treatments that are empirically supported in the general population.

This topical issue on TBI and sleep includes studies addressing critical needs in furthering our clinical and rehabilitation research agenda in this area. The first series of articles highlights the use of technology to objectively characterize sleep to phenotype the disturbance. Holcomb and colleagues20 used level 2 polysomnography to evaluate incidence of sleep apnea in a consecutive series of neurorehabilitation inpatient admissions to a VA Polytrauma Rehabilitation Center. Half of the study sample met criteria for primarily obstructive sleep apnea (49%), with differential predictors of sleep apnea diagnosis and severity across mechanisms of injury.20 Findings suggest that traditional risk factors for the presence or severity of sleep apnea may not apply to TBI and that clinical prediction rules and screening measures may not be sensitive to the presence of sleep apnea in this patient group.20-22 Sandsmark and colleagues23 used continuous electroencephalograms collected in the intensive care unit setting to examine the predictive value of sleep architecture/features on important outcomes including mortality, acute hospital discharge disposition, time to rehabilitation services, and intensity of therapy. Preserved sleep features were found to be predictive of survival, earlier access to rehabilitation, and favorable acute care discharge disposition.23 Although preservation of sleep features may represent less severe injury, statistical analyses did not reveal statistically significant differences between those with and without preserved sleep features on initial Glasgow Coma Scale scores or neuroradiologic summary indices.23 Small sample sizes may have influenced this finding; however, other studies support that injury severity alone does not explain the presence or severity of sleep disturbance.9,20,24 The authors readily identify a limitation of this study was the lack of examination of potentially modifiable factors (medication side effects) that may have contributed to sleep state.23 Authors indicate that medications with these side effects are necessary in the acute care setting but their use over time and potential impact on the sleep state should be considered when addressing sleep.23 Using a gross measure of sleep-wake cycle disturbance (SWCD) and circadian misalignment based on clinician ratings, Holcomb and colleagues24 report that trajectory of cognitive recovery interacts with the presence of SWCD over time. Notably, participants with SWCD demonstrate flat improvement on cognitive tests compared with those who do not evidence an SWCD over time even after adjustment for injury severity.24 Collectively, these 3 studies highlight the significance of sleep in predicting important rehabilitation outcomes (access, cognitive recovery) and identify potential treatment targets (sleep apnea, circadian misalignment, medication side effects) for both clinical practice and research studies.

The next series of articles addresses approaches to sleep measurement in participants with moderate to severe TBI in both acute and chronic stages. Improved understanding of sleep measurement in patients with TBI is important in both clinical and research settings. Kamper and colleagues25 have validated wrist-worn actigraphy against the criterion standard of polysomnography with electroencephalography in patients with moderate to severe TBI. They highlight acceptable concordance of actigraphy against polysomnography in subgroups including those with cognitive impairment, sleep apnea, and spasticity.25 In contrast, Nazem and colleagues26 evaluated discrepancy between actigraphy against self-recorded sleep logs commonly used in clinical and research settings. Their sample of patients with moderate to severe TBI in chronic stages of recovery tolerated study procedures but evidenced poor agreement between the 2 sleep measurement methods, with underreporting of sleep in the sleep diaries by participants.26 The feasibility and improved understanding of accuracy across the sleep measurement measures discussed in these articles will help inform selection of the most appropriate assessment approach in clinical and research contexts.

Finally, the last 2 articles highlight a recurring theme of prevalent sleep disturbances in Veterans with moderate to severe (Mathews and colleagues)27 and mild TBI (Vuletic et al).28 Both articles highlight comorbidities that contribute to sleep disturbance including physical symptoms (pain), mental health (depression, posttraumatic stress disorder), and environmental factors. Qualitative interviews conducted by Mathews and colleagues27 highlight that participants with TBI are motivated to address sleep problems and highlight challenges with current clinical sleep management practices and treatments. In sum, this topical issue on TBI and sleep has highlighted the validity of using the "5-finger" approach to sleep management in TBI, which attributes sleep disturbance to 5 source domains (circadian misalignment, pharmacologic factors, medical factors, psychological factors, and primary sleep medicine diagnoses).29 Studies highlight areas for targeting specific treatments, methods for improved detection, and etiologic considerations.

-Risa Nakase-Richardson, PhD

MHBS, James A. Haley Veterans Hospital

Tampa, Florida

VA HSR&D Center of Innovation in Disability

Rehabilitation and Research (CINDRR)

Tampa, Florida

Defense and Veterans Brain Injury Center (DVBIC)

Department of Medicine, University of South Florida

Tampa, Florida

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