A Narrative Review of Performance and Health Research in US Army Rangers.

ABSTRACT: Roberts, BM, Mantua, J, Naylor, JA, and Ritland, BM. A narrative review of performance and health research in US army rangers. J Strength Cond Res 37(5): 1157-1161, 2023-The 75th Ranger Regiment (75RR) is an elite airborne infantry unit that is prepared to deploy on short notice and is resourced to maintain exceptional proficiency and readiness through prolonged deployments. Soldiers must be airborne qualified and pass a number of physical and psychological tests during training to become a member of 75RR. Rangers must maintain a level of physical performance comparable to high-level athletes while also handling operational stressors that include a negative-energy balance, high-energy expenditure, sleep restriction, and completing missions in extreme environments, all of which increase their chance of illness or infection. There are also situations of heighted injury risk, such as parachuting and repelling, which are routinely required in combat operations. Thus far, only one screening tool to assess injury risk has been developed. There are also physical training programs to enhance performance for Rangers in 75RR. This narrative review aims to evaluate the body of literature surrounding performance and health-related research in US Army Rangers to understand how Rangers are impacted during training or operations, to inform future training recommendations, and to identify areas of future research that are warranted and could potentially optimize the health and performance of Rangers during future training or operation events.

Emotion habituation is accelerated in chronic mild traumatic brain injury.

Primary Objective: Risk for mental health disturbances (e.g., depression and anxiety), is elevated following a mild traumatic brain injury (mTBI), even in the chronic stages of injury. In our previous work, we found individuals with chronic mTBI have decreased emotion habituation. The objective of the current study was to test whether reduced habituation is a mechanism underlying increased risk for mental health disturbances following mTBI. Research Design: We used a cross-sectional assessment of emotion habituation in a sample of young adults at least 1 year after an mTBI. Methods and Procedures: We repeatedly showed mTBI and control participants the same set of highly arousing, negative images and positive images. Participants rated each image for arousal and valence. Main Outcomes and Results: Unexpectedly, we found individuals with mTBI habituated faster to emotional images than controls. However, enhanced habituation was not linkd with emotional outcomes. Participants with mTBI did not differ from controls for reactivity, but blunted reactivity in all participants was associated with higher depressive symptoms. Conclusions: Although there are subtle differences in emotion responses in chronic mTBI, the differences were not associated with mental health disturbances. Nevertheless, this difference in emotional processing may increase risk for untested mental health issues.

The role of sleep in emotional memory processing in middle age.

Sleep benefits memory in young adults, and this effect may be particularly strong for representations associated with negative emotion. Many aspects of sleep important for memory consolidation change with aging, particularly by middle age, suggesting that sleep-related consolidation may be reduced. However, the influence of sleep on memory has rarely been investigated in a middle-aged population. In the current study, young and middle-aged adults viewed negative and neutral pictures and underwent a recognition test after sleep or wake. Subjective emotional reactivity was also measured. Compared to waking, sleep benefited memory in young adults. Performance did not differ between sleep and wake groups in middle-aged adults, and it matched the level of young adults who slept. The effect of sleep versus wake was not influenced by memory valence in either age group. These results suggest the relative influence of sleep compared to wake on memory declines with aging, specifically by middle age, and that this decline extends to negative memory.

Age-related Changes in the Sleep-dependent Reorganization of Declarative Memories.

Consolidation of declarative memories has been associated with slow wave sleep in young adults. Previous work suggests that, in spite of changes in sleep, sleep-dependent consolidation of declarative memories may be preserved with aging, although reduced relative to young adults. Previous work on young adults shows that, with consolidation, retrieval of declarative memories gradually becomes independent of the hippocampus. To investigate whether memories are similarly reorganized over sleep at the neural level, we compared functional brain activation associated with word pair recall following a nap and equivalent wake in young and older adults. SWS during the nap predicted better subsequent memory recall and was negatively associated with retrieval-related hippocampal activation in young adults. In contrast, in older adults there was no relationship between sleep and memory performance or with retrieval-related hippocampal activation. Furthermore, compared with young adults, postnap memory retrieval in older adults required strong functional connectivity of the hippocampus with the PFC, whereas there were no differences between young and older adults in the functional connectivity of the hippocampus following wakefulness. These results suggest that, although neural reorganization takes place over sleep in older adults, the shift is unique from that seen in young adults, perhaps reflecting memories at an earlier stage of stabilization.

Sleep benefits consolidation of visuo-motor adaptation learning in older adults.

Sleep is beneficial for performance across a range of memory tasks in young adults, but whether memories are similarly consolidated in older adults is less clear. Performance benefits have been observed following sleep in older adults for declarative learning tasks, but this benefit may be reduced for non-declarative, motor skill learning tasks. To date, studies of sleep-dependent consolidation of motor learning in older adults are limited to motor sequence tasks. To examine whether reduced sleep-dependent consolidation in older adults is generalizable to other forms of motor skill learning, we examined performance changes over intervals of sleep and wake in young (n = 62) and older adults (n = 61) using a mirror-tracing task, which assesses visuo-motor adaptation learning. Participants learned the task either in the morning or in evening, and performance was assessed following a 12-h interval containing overnight sleep or daytime wake. Contrary to our prediction, both young adults and older adults exhibited sleep-dependent gains in visuo-motor adaptation. There was a correlation between performance improvement over sleep and percent of the night in non-REM stage 2 sleep. These results indicate that motor skill consolidation remains intact with increasing age although this relationship may be limited to specific forms of motor skill learning.

Reliability of Sleep Measures from Four Personal Health Monitoring Devices Compared to Research-Based Actigraphy and Polysomnography.

Polysomnography (PSG) is the "gold standard" for monitoring sleep. Alternatives to PSG are of interest for clinical, research, and personal use. Wrist-worn actigraph devices have been utilized in research settings for measures of sleep for over two decades. Whether sleep measures from commercially available devices are similarly valid is unknown. We sought to determine the validity of five wearable devices: Basis Health Tracker, Misfit Shine, Fitbit Flex, Withings Pulse O2, and a research-based actigraph, Actiwatch Spectrum. We used Wilcoxon Signed Rank tests to assess differences between devices relative to PSG and correlational analysis to assess the strength of the relationship. Data loss was greatest for Fitbit and Misfit. For all devices, we found no difference and strong correlation of total sleep time with PSG. Sleep efficiency differed from PSG for Withings, Misfit, Fitbit, and Basis, while Actiwatch mean values did not differ from that of PSG. Only mean values of sleep efficiency (time asleep/time in bed) from Actiwatch correlated with PSG, yet this correlation was weak. Light sleep time differed from PSG (nREM1 + nREM2) for all devices. Measures of Deep sleep time did not differ from PSG (SWS + REM) for Basis. These results reveal the current strengths and limitations in sleep estimates produced by personal health monitoring devices and point to a need for future development.

Apnea-induced rapid eye movement sleep disruption impairs human spatial navigational memory.

Hippocampal electrophysiology and behavioral evidence support a role for sleep in spatial navigational memory, but the role of particular sleep stages is less clear. Although rodent models suggest the importance of rapid eye movement (REM) sleep in spatial navigational memory, a similar role for REM sleep has never been examined in humans. We recruited subjects with severe obstructive sleep apnea (OSA) who were well treated and adherent with continuous positive airway pressure (CPAP). Restricting CPAP withdrawal to REM through real-time monitoring of the polysomnogram provides a novel way of addressing the role of REM sleep in spatial navigational memory with a physiologically relevant stimulus. Individuals spent two different nights in the laboratory, during which subjects performed timed trials before and after sleep on one of two unique 3D spatial mazes. One night of sleep was normally consolidated with use of therapeutic CPAP throughout, whereas on the other night, CPAP was reduced only in REM sleep, allowing REM OSA to recur. REM disruption via this method caused REM sleep reduction and significantly fragmented any remaining REM sleep without affecting total sleep time, sleep efficiency, or slow-wave sleep. We observed improvements in maze performance after a night of normal sleep that were significantly attenuated after a night of REM disruption without changes in psychomotor vigilance. Furthermore, the improvement in maze completion time significantly positively correlated with the mean REM run duration across both sleep conditions. In conclusion, we demonstrate a novel role for REM sleep in human memory formation and highlight a significant cognitive consequence of OSA.

Physical sleeping environment is related to insomnia risk and measures of readiness in US army special operations soldiers.

BACKGROUND: US military service members have characteristically poor sleep, even when 'in garrison' or at one's home base. The physical sleeping environment, which is often poor in military-provided housing or barracks, may contribute to poor sleep quality in soldiers. The current study aimed to assess whether the sleeping environment in garrison is related to sleep quality, insomnia risk and military readiness. METHODS: Seventy-four US army special operations soldiers participated in a cross-sectional study. Soldiers were queried on their sleeping surface comfort and the frequency of being awakened at night by excess light, abnormal temperatures and noise. Subjective sleep quality and insomnia symptoms were also queried, via the Pittsburgh Sleep Quality Index and Insomnia Severity Index, respectively. Lastly, measures of soldier readiness, including morale, motivation, fatigue, mood and bodily pain, were assessed. RESULTS: Soldiers reporting temperature-related and light-related awakenings had poorer sleep quality higher fatigue and higher bodily pain than soldiers without those disturbances. Lower ratings of sleeping surface comfort were associated with poorer sleep quality and lower motivation, lower morale, higher fatigue and higher bodily pain. Each 1-point increase in sleeping surface comfort decreased the risk for a positive insomnia screen by 38.3%, and the presence of temperature-related awakenings increased risk for a positive insomnia screen by 78.4%. Those living on base had a poorer sleeping environment than those living off base. CONCLUSION: Optimising the sleep environment-particularly in on-base, military-provided housing-may improve soldier sleep quality, and readiness metrics. Providers treating insomnia in soldiers should rule out environment-related sleep disturbances prior to beginning more resource-intensive treatment.

Sleep and Infantry Battle Drill Performance in Special Operations Soldiers.

BACKGROUND: Although multiple studies have documented the impact of insufficient sleep on soldier performance, most studies have done so using artificial measures of performance (e.g., tablet or simulator tests). The current study sought to test the relationship between sleep and soldier performance during infantry battle drill training, a more naturalistic measure of performance.METHODS: Subjects in the study were 15 junior Special Operations infantry soldiers. Soldiers wore an actigraph and reported their subjective sleep duration and quality prior to close quarter battle (CQB) drills. Experienced leaders monitored each iteration of the CQB exercise and recorded the number of errors committed.RESULTS: The number of errors committed during the live ammunition iterations was negatively correlated with subjective number of hours slept and subjective sleep efficiency/quality during the month prior. Soldiers with subjective sleep duration ≥7 h had a significantly lower number of errors than soldiers with subjective sleep duration <7 h (1.71 vs. 0.63 errors), and soldiers with sleep quality <85% committed more errors than those with sleep quality ≥85% (1.50 vs. 0.40 errors).DISCUSSION: These data preliminarily suggest that sleep quality and duration may influence subsequent performance on infantry battle drill training, particularly for soldiers with limited experience in battle drill conduction who have not yet perfected battle drill techniques. Future studies should enact sleep augmentation to determine the causal influence of sleep on performance in this setting.Mantua J, Shevchik JD, Chaudhury S, Eldringhoff HP, Mickelson CA, McKeon AB. Sleep and infantry battle drill performance in Special Operations soldiers. Aerosp Med Hum Perform. 2022; 93(7):557-561.

Age-related changes in sleep-dependent novel word consolidation.

Learning new words is a vital, life-long process that benefits from memory consolidation during sleep in young adults. In aging populations, promoting vocabulary learning is an attractive strategy to improve quality of life and workplace longevity by improving the integration of new technology and the associated terminology. Decreases in sleep quality and quantity with aging may diminish sleep-dependent memory consolidation for word learning. Alternatively, given that older adults outperform young adults on vocabulary-based tasks, and that strength of memory encoding (how well older adults learn) predicts sleep-dependent memory consolidation, word learning may uniquely benefit from sleep in older adults. We assessed age-related changes in memory for novel English word-definition pairs recalled following intervals spent asleep and awake. While sleep was shown to fully preserve memory for word/definition pairs in young adults (N = 53, asleep = 32, awake = 21, 18-30 years), older adults (N = 45, asleep = 21, awake = 24, 58-75 years) forgot items equally over wake and sleep intervals but preserved the accuracy of typed responses better following sleep. However, this was modulated by the strength of encoded memories: the proportion of high strength items consolidated increased for older adults following sleep compared to wake. Older adults consolidated a lower proportion of medium strength items across both sleep and wake intervals compared to young adults. Our results contribute to growing evidence that encoding strength is crucially important to understand the expression of sleep-dependent benefits in older adults and assert the need for sufficiently sensitive performance metrics in aging research.

Sleep duration prior to an enterotoxigenic Escherichia coli challenge predicts diarrhea severity during infection.

BACKGROUND: Acute diarrhea is the most frequent diagnosis among ill travelers. Sleep loss may weaken the body's defense against pathogens and increase susceptibility to infection. The relationship between sleep and infectious diarrhea has not been studied and was assessed utilizing data from a controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC). METHODS: During a CHIM assessing the efficacy of an immunoprophylactic targeting ETEC against moderate-to-severe diarrhea (MSD) following challenge, we measured sleep via actigraphy over an 8-day inpatient period. We hypothesized better sleep pre-challenge would predict illness symptomatology following challenge. RESULTS: Among 57 participants (aged 34.4 ± 8.1 years, 64% male), there was no relationship between sleep metrics and incidence of MSD. However, longer total sleep time the night preceding ETEC challenge was associated with lower maximum 24 h diarrhea volume (B = -1.80, p = 0.01) and total diarrhea volume (B = -2.45, p = 0.01). CONCLUSIONS: This novel study showed that shorter sleep duration predicted diarrhea severity over the course of an ETEC infection. Future work should experimentally manipulate sleep to further clarify its impact on diarrhea-related outcomes for ETEC and other important enteric pathogens.

Active Duty Service Members, Primary Managers, and Administrators' Perspectives on a Novel Sleep Telehealth Management Platform in the U.S. Military Healthcare System.

INTRODUCTION: Sleep disorders are common in the military, and there is a gross shortage of sleep specialists in the military health system. The purposes of the present study were to (1) understand perceptions and expectations surrounding sleep telehealth approaches and (2) solicit feedback to optimize and refine a proposed novel sleep telehealth management platform. To accomplish these objectives, we investigated the perceptions, expectations, and preferences of active duty service members (ADSMs) with sleep disorders, primary care managers (PCMs), and administrative stakeholders regarding sleep telehealth management. MATERIALS AND METHODS: Using convenience sampling, we conducted five focus groups with 26 ADSMs and 11 individual interviews with PCMs from two military treatment facilities in the U.S National Capital Region and 11 individual interviews with administrative sleep stakeholders (9 military and 2 civilian). RESULTS: Active duty service members, PCMs, and administrative stakeholders provided insight regarding expectations for sleep telehealth as well as suggestions to optimize the novel sleep telehealth platform. In terms of outcomes, ADSMs expected sleep telehealth to improve sleep and convenience. Primary care managers expected improved sleep and other comorbidities, enhanced operational readiness, and reduced mortalities among their patients. Administrators expected increased access to care, optimized utilization of health services, realized cost savings, reduced accidents and errors, and improved military performance. In terms of the platform, for ADSMs, desired characteristics included delivery of timely clinical reports, improved patient-provider communication, and enhanced continuity of care. For PCMs and administrators,an ideal sleep telehealth solution will improve the diagnosis and triage of sleep patients, save PCM time, be easy to use, and integrate with the electronic health record system. CONCLUSION: The proposed sleep telehealth platform appealed to nearly all participants as a significant force multiplier to enhance sleep disorder management in the military. Stakeholders offered valuable recommendations to optimize the platform to ensure its successful real-world implementation.

Self-Reported Sleep Need, Subjective Resilience, and Cognitive Performance Following Sleep Loss and Recovery Sleep.

OBJECTIVE: Individuals vary in response to sleep loss: some individuals are "vulnerable" and demonstrate cognitive decrements following insufficient sleep, while others are "resistant" and maintain baseline cognitive capability. Physiological markers (e.g., genetic polymorphisms) have been identified that can predict relative vulnerability. However, a quick, cost-effective, and feasible subjective predictor tool has not been developed. The objective of the present study was to determine whether two factors-"subjective sleep need" and "subjective resilience"-predict cognitive performance following sleep deprivation. METHODS: Twenty-seven healthy, sleep-satiated young adults participated. These individuals were screened for sleep disorders, comorbidities, and erratic sleep schedules. Prior to 40 hours of in-laboratory total sleep deprivation, participants were questioned on their subjective sleep need and completed a validated resilience scale. During and after sleep deprivation, participants completed a 5-minute psychomotor vigilance test every 2 hours. RESULTS: Both subjective resilience and subjective sleep need individually failed to predict performance during sleep loss. However, these two measures interacted to predict performance. Individuals with low resilience and low sleep need had poorer cognitive performance during sleep loss. However, in individuals with medium or high resilience, psychomotor vigilance test performance was not predicted by subjective sleep need. Higher resilience may be protective against sleep loss-related neurobehavioral impairments in the context of subjective sleep need. CONCLUSIONS: Following sleep loss (and recovery sleep), trait resilient individuals may outperform those with lower resiliency on real-world tasks that require continuous attention. Future studies should determine whether the present findings generalize to other, operationally relevant tasks and additional cognitive domains.

Transitioning from daytime to nighttime operations in military training has a temporary negative impact on dynamic balance and jump performance in U.S. Army Rangers.

OBJECTIVES: Explore the impact transitioning from daytime to nighttime operations has on performance in U.S. Army Rangers. METHODS: Fifty-four male Rangers (age 26.1±4.0 years) completed the Y-Balance Test (YBT), a vertical jump assessment, and a grip strength test at three time points. Baseline testing occurred while the Rangers were on daytime operations; post-test occurred after the first night into the nighttime operation training (after full night of sleep loss), and follow-up testing occurred six days later (end of nighttime training). RESULTS: On the YBT, performance was significantly worse at post-test compared to baseline during right posteromedial reach (104.1±7.2cm vs 106.5±6.7cm, p=.014), left posteromedial reach (105.4±7.5cm vs 108.5±6.6cm, p=.003), right composite score (274.8±19.3cm vs 279.7±18.1cm, p=.043), left composite score (277.9±18.1cm vs 283.3±16.7cm, p=.016), and leg asymmetry was significantly worse in the posterolateral direction (4.8±4.0cm vs 3.7±3.1cm, p=.030) and the anterior direction (5.0±4.0cm vs 3.6±2.6cm, p=.040). The average vertical jump height was significantly lower at post-test compared to baseline (20.6±3.4 in vs 21.8±3.0 in, p=.004). Baseline performance on YBT and vertical jump did not differ from follow-up. CONCLUSIONS: Army Rangers experienced an immediate, but temporary, drop in dynamic balance and vertical jump performance when transitioning from daytime to nighttime operations. When feasible, Rangers should consider adjusting their sleep cycles prior to anticipating nighttime operations in order to maintain their performance levels. Investigating strategies that may limit impairments during this transition is warranted.

Association Between Self-Reported Sleep Quality and Musculoskeletal Injury in Male Army Rangers.

INTRODUCTION: Musculoskeletal injuries and insufficient sleep are common among U.S. Army Rangers. There has been limited research into whether indices of sleep differ between injured and uninjured Rangers. The purpose of this study was to investigate the association between self-reported sleep and musculoskeletal injury in Rangers. MATERIALS AND METHODS: A total of 82 Army Rangers (male, 25.4 ± 4.0 years) were asked if they currently have any musculoskeletal injuries; completed the Pittsburgh Sleep Quality Index (PSQI), the Insomnia Severity Index (ISI), and the Stanford Sleepiness Scale; and were asked about their average sleep quality/sleep duration over the preceding week. Rangers were then dichotomized into groups, one that reported a current musculoskeletal injury and another that did not. RESULTS: The reported musculoskeletal injury prevalence was 15.9% (n = 13). The Rangers that reported an injury, compared to those that did not, had a significantly higher Global PSQI score (6.7 ± 3.7 versus 4.5 ± 2.7, P = .012) and ISI score (10.9 ± 3.7 versus 7.2 ± 4.1, P = .003), both indicative of poorer sleep. The group reporting an injury rated their average sleep quality over the preceding week significantly lower compared to those that did not report an injury (50.8 ± 17.5 versus 68.9 ± 18.3, P = .001). There was no significant group difference in the average nightly sleep duration (6.1 ± 1.0 hours versus 6.5 ± 0.9 hours, P = .099). CONCLUSION: In this cohort of male Army Rangers, In this cohort of male Army Rangers, those with a musculoskeletal injury reported poorer sleep quality than uninjured Rangers. Sleep duration was not associated with reported injuries; however, both the injured group and uninjured group averaged less than the recommended amounts of sleep. Further investigation into the relationship between musculoskeletal injury and sleep in military personnel is warranted.

Sleep and occupational well-being in active duty special operations soldiers: A replication and expansion.

OBJECTIVE: To assess the relationship between sleep quality and occupational well-being in active duty military Service Members. DESIGN: Longitudinal prospective analysis. SETTING: An annual military training event. PARTICIPANTS: US Army special operations Soldiers (n = 60; 100% male; age 25.41 ± 3.74). INTERVENTION: None. MEASUREMENTS: The Pittsburgh Sleep Quality Index (PSQI) was administered prior to the training event, and the Emotional Exhaustion Scale, the Role Overload Scale, the Walter Reed Army Institute of Research Soldier-Specific Functional Impairment Scale, and the Perceived Stress Scale were administered after the event. Linear regression models were used to assess the relationship between sleep and occupational wellness measures, and the outcome measures of "good" and "poor" sleepers (per the PSQI scoring criteria) were compared with Student's t tests. RESULTS: Higher (poorer) PSQI Global Scores predicted poorer occupational wellness of all measures (emotional exhaustion: B = 1.60, P < .001, R2 = 0.25; functional impairment: B = 0.29, P = .03, R2 = 0.14; role overload: B = 0.28, P = .008, R2 = 0.12; and perceived stress: B = 0.34, P = .004, R2 = 0.20). There were additional relationships between specific PSQI component scores and occupational wellness measures, which is a replication of This team's previous work. Furthermore, emotional exhaustion (t(58) = -4.18, P < .001), functional impairment (t(59)= -3.68, P = .001), role overload (t(58) = -3.20, P = .002), and perceived stress (t(58) = -2.43, P = .02) were all higher in poor sleepers. CONCLUSIONS: The findings of this study suggest that US Army special operations Soldiers who have poorer sleep quality may be at increased risk for having poorer occupational well-being.

Sleep and high-risk behavior in military service members: a mega-analysis of four diverse U.S. Army units.

Experimental sleep restriction and deprivation lead to risky decision-making. Further, in naturalistic settings, short sleep duration and poor sleep quality have been linked to real-world high-risk behaviors (HRB), such as reckless driving or substance use. Military populations, in general, tend to sleep less and have poorer sleep quality than nonmilitary populations due to a number of occupational, cultural, and psychosocial factors (e.g. continuous operations, stress, and trauma). Consequently, it is possible that insufficient sleep in this population is linked to HRB. To investigate this question, we combined data from four diverse United States Army samples and conducted a mega-analysis by aggregating raw, individual-level data (n = 2,296, age 24.7 ± 5.3). A negative binomial regression and a logistic regression were used to determine whether subjective sleep quality (Pittsburgh Sleep Quality Index [PSQI], Insomnia Severity Index [ISI], and duration [h]) predicted instances of military-specific HRB and the commission of any HRB (yes/no), respectively. Poor sleep quality slightly elevated the risk for committing HRBs (PSQI Exp(B): 1.12 and ISI Exp(B): 1.07), and longer duration reduced the risk for HRBs to a greater extent (Exp(B): 0.78), even when controlling for a number of relevant demographic factors. Longer sleep duration also predicted a decreased risk for commission of any HRB behaviors (Exp(B): 0.71). These findings demonstrate that sleep quality and duration (the latter factor, in particular) could be targets for reducing excessive HRB in military populations. These findings could therefore lead to unit-wide or military-wide policy changes regarding sleep and HRB.

Poor Subjective Sleep Quality Is Associated with Poor Occupational Outcomes in Elite Soldiers.

We aimed to assess the relationship between subjective sleep quality and occupationally-relevant outcomes in military personnel. Participants were from an elite unit of US Army soldiers who worked extended (~30 h) shifts (with minimal recovery time between shifts) during 3-week work sessions. Questionnaires assessing subjective sleep quality during the month prior (Pittsburgh Sleep Quality Index [PSQI]) were administered at the beginning of the session. Occupational outcomes (emotional exhaustion, functional impairment, role overload, daytime sleepiness) were assessed on the final day of the session. Regression analyses were conducted to link sleep quality and occupational outcomes. The study sample participants had relatively poor sleep prior to the exercise (PSQI Global score average = 6.3 ± 3.1). Higher PSQI Global Scores prior to the work session longitudinally predicted daytime sleepiness (f2: 0.56) after the work session. PSQI component 7, which queries daytime dysfunction attributed to poor sleep quality, longitudinally predicted emotional exhaustion, functional impairment, and role overload (f2 range: 0.19-0.70). In conclusion, poor sleep quality-in aggregation with occupationally-mandated sleep loss-is predictive of poorer subsequent occupational outcomes. Future work should aim to increase sleep opportunities prior to occupationally-mandated sleep loss in order to build resilience when sleep loss is unavoidable.

Sleep loss is related to unstable stationary balance in U.S. Army soldiers in an operationally-relevant context.

BACKGROUND: Sleep loss negatively impacts stationary balance in a laboratory setting, but few studies have examined this link in a naturalistic environment. We tested this relationship in U.S. Army soldiers that often undergo mission-driven sleep loss and who conduct high-risk operations on precarious terrain. METHODS: Stationary balance was tested before and after a mission night. RESULTS: After mission-driven sleep loss, in more difficult conditions (but not easy conditions) balance was more unstable and more variable than a rested baseline condition. Furthermore, habitual sleep quality prior to sleep loss predicted the balance decrement after sleep loss. CONCLUSIONS: Therefore, mission-driven sleep loss may negatively impact soldier balance, but better sleep prior to the mission may mitigate these negative effects.

A Review of Environmental Barriers to Obtaining Adequate Sleep in the Military Operational Context.

INTRODUCTION: Sleep loss is ubiquitous in military settings, and it can be deleterious to cognitive, physiological, and operational functioning. This is especially true in the military operational context (e.g., training, garrison, combat) where continuous operations prevent adequate time for rest and recuperation. Furthermore, even when servicemembers do have opportunities for sleep, environmental disruptors in the military operational context make it difficult to obtain restorative sleep. Such environmental disruptors are potentially preventable or reversible, yet there is little public awareness of how to minimize or eliminate these sleep disruptors. Therefore, the goal of this review was to outline prominent environmental sleep disruptors, describe how they occur in the military operational context, and also discuss feasible strategies to mitigate these disruptors. MATERIALS AND METHODS: We discuss four factors - light, noise, temperature, and air pollution - that have previously been identified as prominent sleep disruptors in non-military settings. Additionally, we extracted publicly-available yearly temperature and pollution data, from the National Oceanic and Atmospheric Association and the Environmental Protection Agency, respectively, for major prominent military installations in the continental US in order to identify the sites at which servicemembers are at the greatest risk for environmental sleep disruptions. RESULTS: Based on previous literature, we concluded light and noise are the most easily mitigatable sleep-disrupting environmental factors. Air pollution and temperature, on the other hand, are more difficult to mitigate. We also propose that harsh/uncomfortable sleeping surface is a fifth critical, previously unexplored sleep disruptor in the military operational context. Furthermore, we identified several problematic military sites for air pollution for temperature. Specifically, each branch has major installations located in regions with extreme heat (especially the Army), and each branch has at least one major installation in a high air pollution region. These findings show that even when in training or garrison in the US, military servicemembers are at risk for having sleep disruption due to environmental factors. CONCLUSIONS: Environmental disruptors, such as light, noise, temperature, and air pollution, can negatively impact sleep in the military operational context. Simple, feasible steps can be taken to reduce sleep disruptions that are caused by light and noise. Yet there is a need for research and development on tools to mitigate air pollution, extreme temperatures, and inhospitable sleeping surfaces. Leadership at the discussed military bases and training facilities should focus on improving the sleep environment for individuals under their command. Such interventions could ultimately improve warfighter health, wellness, and operational performance, leading to greater warfighter readiness and lethality.