Abstract Introduction Circadian misalignment is detrimental to health and performance– decrements that can be exacerbated by rapid transmeridian travel. Such travel is unavoidable in military operations but can itself negatively impact the likelihood of mission success. To date, there are few studies assessing the impact of travel on the physiology and operational performance of military personnel. In the present study, salivary dim light melatonin onset (DLMO) is used to assess the extent to which circadian rhythms are impacted by transmeridian travel and round-the-clock missions. Methods Participants were 23 active-duty male Soldiers aged 23.2 ± 2.8 years (M ± SD). Baseline data were collected in the Hawaii Standard Time (HST) Zone. This was followed by rapid deployment to the Eastern Daylight Time Zone for one pre-mission day, followed by a 72-hour live-fire exercise, and two post-mission days. Salivary melatonin was assessed via a modified constant routine at baseline, upon arrival to the EDT zone, and again on the first post-mission day, with 12 passive drool saliva samples collected every 30 minutes from 1830 to 0000 hours under dim light (< 10 lux) and sedentary conditions. Participants abstained from food and drink (except for water) during the assessment. The circadian phase shift for the mission was calculated as the time difference between baseline and post-mission DLMO. Results During the pre-mission day, 19 participants displayed the anticipated melatonin suppression (no DLMO) upon arrival to the EDT zone. During the mission, 15 Soldiers had a circadian phase delay [ ~66 min (±72 min), (M ± SD)], and 8 Soldiers had a circadian phase advance [~90 min (± 96 min), (M±SD). Conclusion As anticipated, participants’ circadian rhythms were misaligned with the local day immediately upon arrival to the EDT. For all but 1 participant, circadian timing at post-mission was similar to circadian timing at baseline. Further analyses are underway to determine the extent of misalignment on the pre-mission day resulting from travel. Further research is needed to assess the extent to which transmeridian travel and round-the-clock operations impact circadian misalignment, rate of adaptation to the new time zone, and operationally relevant performance. Support (if any) DoD MOMRP; DEVCOM-SC

Dear Editor, Understanding how policy changes, such as a drawdown from a major military campaign, impact service members can provide information on how best to preserve service member health and resilience during these events. US special operations forces (SOF) units served in Afghanistan

Abstract Introduction In a previous study, we found that morning circadian preference and increased fatigue were associated with increased injuries during a nocturnal parachute jump. The purpose of the present study was to replicate this finding, and expand upon it by determining whether, and the extent to which, subjective sleep ratings are also predictive of injury during parachute jumps. Methods Participants included 27 male active duty Soldiers aged 23.7 ± 2.9 years (M ± SD). Participants completed a series of questionnaires at baseline (1 week prior to jump), pre-jump (1 hour before), and post-jump (1 hour after). Questionnaires about sleep; insomnia symptoms; circadian preference (morning vs. evening); injuries; and subjective experiences of sleepiness, fatigue, and jump quality were administered. Results Circadian preference was correlated with ‘sleep quality over the previous month’ (r = -.537, p < .01) and week (r = -.502, p < .01) with those indicating evening preference reporting poorer sleep quality. There was no correlation between circadian preference and average total sleep time. No participants had Insomnia Severity Index (ISI) scores above the clinical threshold for insomnia. However, those indicating an evening circadian preference had higher ISI scores (r = .635, p < 0.001). No significant correlations between circadian preference and previous jump injuries, subjective ratings of parachute landing fall (PLF) quality, or landing hardness were found. Likewise, momentary sleepiness and subjective fatigue were not significantly correlated with PLF or landing hardness. Conclusion In this sample of young Soldiers, evening circadian preference was associated with poorer subjective sleep quality and more insomnia-related symptoms. However, neither circadian preference nor fatigue level was significantly correlated with number of previous jump injuries or subjective ratings of jump performance. Given the small sample size and the generally high skill level of the population of parachutists, it is possible that the present n was not sufficient to detect an effect of circadian preference on injuries or jump quality. In future studies, objective measures of sleep should be added, the n should be increased, and the subject sample should include parachutists with a broader range of experience and training. Support (if any) Department of Defense Military Operational Medicine Research Program (MOMRP)

Abstract Introduction The military works under 24/7 operations which can lead to sleep loss and Soldier fatigue. Both sleep loss and fatigue impact functionality and success of the Soldier and ultimately, the entire unit. The functional impact of sleepiness and fatigue can be present differently. Therefore, clarifying the relationship between subjective sleepiness and fatigue is important for military readiness and provides leadership with critical information to ensure mission success. Methods Fifty-one healthy, young male participants were recruited from a sample of active-duty Soldiers. The study lasted 5 days with a 72-hour live-fire mission simulation from days 2 to 4. On each of these days, Soldiers completed daily morning surveys, including measures of sleepiness using the Epworth Sleepiness Scale (an 8-question measure to identify clinical sleepiness) as well as subjective fatigue through the Visual Analog Scale. Results A repeated measures ANOVA showed a significant main effect for subject sleepiness and fatigue among mission days (p < 0.05). Linear regression indicated sleepiness scores were significantly predictive of fatigue each mission day. Conclusion On mission day 3 during the 72-hour live fire mission, soldiers were significantly more sleepy and more fatigued compared to other mission days. Additionally, for each mission day, subjective sleepiness was predictive of soldier fatigue. Understanding this relationship and its predictive nature can help military leadership plan accordingly for mission and training events to maximize success in operational contexts. Support (if any) Department of Defense Military Operational Medicine Research Program (MOMRP); DEVCOM SC

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.

Abstract Introduction As a result of the global COVID-19 pandemic, there have been significant challenges conducting clinical sleep research. Participant recruitment has been a particular challenge due to federal safety guidelines and institutional directives. The purpose of this project is to describe the adaptation of an in-person study protocol (of sleep problems among military service members and their families) to an entirely remote approach. Methods Prior to COVID-19, planned research methods included in-person recruitment, enrollment, and study support; approved by the Institutional Review Board (IRB) of Walter Reed National Military Medical Center (WRNMMC), Fort Belvoir Community Hospital (FBCH), and the University of Maryland, Baltimore (UMB). As COVID-19 restrictions increased, the research team adapted to a fully remote approach (via phone/email) and developed a “research call center” to replace in-clinic recruitment/enrollment. Detailed operating procedures were standardized, including shipping study materials (wearable device) via FedEx. Following enrollment, participants completed multiple assessments, sleep diaries 2x/day over 10 days, and a post-monitoring satisfaction survey. Results Thirty-five participants between the ages of 18-75 years (M= 46 years, SD= 15.8) were successfully recruited from the Internal Medicine clinic and Sleep Disorders Center at WRNMMC. Following data collection, the research team debriefed and developed recommendations to execute a successful remote study protocol. Three key operational domains were identified: research team, remote procedures, and data management. Recommendations included 1) prioritizing consistent communication, mutual support, and personal wellbeing among the research team, 2) advancing recruitment by establishing and refining preferred recruitment pathways, and 3) providing critical attention to remote data management—allocating responsibilities to regulate the evolving changes of multiple data sources. In addition, partnering closely with IRB personnel was invaluable to refine procedures and maintain regulatory compliance. Conclusion Despite challenges associated with the on-going pandemic, researchers can conduct high-quality clinical research by transitioning to a fully remote study approach. These recommendations can help guide investigative teams to transition from in-person protocols to remote approaches, thus advancing the perpetuation of research activities through a pandemic. Support (If Any) This research was supported by an investigator-initiated research award from the Department of Defense (via the Medical Technology Enterprise Consortium) to the University of Maryland, Baltimore (PI: EMW).

Abstract Introduction Circadian misalignment from sustained 24/7 operations and sleep loss are common occurrences in military operations, and operational demands can often lead to high levels of fatigue. Although the relationship between the circadian system and fatigue is well characterized, the relationship between magnitude of the circadian shift and fatigue during operational mission events has not been widely explored. Methods Twenty-one male participants aged 23.3±3.9 years (mean±SD) were recruited from a sample of active-duty Soldiers. The study consisted of a single day baseline data collection and then a month later the Soldiers participated in a sustained live-fire mission simulation consisting of a pre-mission day, the 72-hour live-fire exercise, and post-mission day. During the simulation, Soldiers completed the following mission events: Tactical Stress Marksmanship Assessment (TSMA), Individual Shooter Scenario (ISS), Small Unit Performance Analytics (SUPRA), Reconnaissance (RECON), infiltration and extraction ruck-march (INFIL/EXFIL RUCK), and RAID, to model actual combat or operational activities. Subjective fatigue was assessed using a Visual Analog Scale (VAS) after each mission event. Circadian phase was measured by salivary dim light melatonin onset (DLMO) at baseline and then again following the post-mission day. Half-hourly saliva samples were collected under dim light (<10lux) sedentary conditions. The circadian phase shift was calculated as the difference between the two DLMO collections. Results Twenty of the twenty-one participants advanced their circadian rhythm with a total mean shift of 0.91±0.88 SD hours. Of the six mission events, significant correlations were found between the magnitude of the phase shift and subjective fatigue for three of the events. The magnitude of the circadian phase shift was negatively correlated with fatigue for RECON r=-0.59 (p=0.008), RAID r=-0.55 (p=0.01), and EXFIL RUCK r=-0.44 (p=0.046). The amount of sleep in the 24 hours prior to each of these events had no significant correlation. Conclusion For the RECON, RAID, and RUCK, we found that the greater the magnitude of the phase shift, the less fatigue individuals endorsed. Yet, there was no significant relationship with sleep prior to the events. This suggests a potential greater need to consider the impact of the circadian system on military operations, especially with regard to circadian effects on fatigue. Support (If Any) Department of Defense Military Operational Medicine Research Program (MOMRP); DEVCOM SC

Introduction 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 Fifteen junior special operations infantry Soldiers participated in the study. Soldiers wore Phillips Actiwatch Spectrum and reported their subjective sleep duration and quality during the week prior to Close Quarters Battle (CQB) drills. CQB training emphasizes close quarter combat tactics and requires a diverse range of cognitive skills (e.g., memory, decision-making, scanning). Each team of Soldiers performed six iterations of CQB – three using Ultimate Training Munitions (UTM; non-lethal rounds of munition) and three with live ammunition. Experienced leaders monitored each iteration and recorded errors on scorecards that are regularly used by the unit during CQB trainings. Results Participating Soldiers were all male and were 24.3 ± 3.82 years old. Soldiers slept an average of 6.6 hours per night leading up to the exercise and had an average sleep efficiency of 82/100%. The average number of errors committed during the UTM trials was 2.5 ± 1.9, and the average number of errors during the live ammunition trials was 1.1 ± 1.1. The number of errors committed during the live ammunition iterations was negatively correlated with subjective number of hours slept (r = -.67, p = .006) and subjective sleep efficiency/quality (r = -.55, p = .03). A t-test showed those with subjective sleep duration ≥ 7 hours had a significantly lower number of errors than Soldiers with subjective sleep duration < 7 hours (t(14) = 2.26, p = .04). Conclusion Enhancing infantry battle drill performance during training may directly translate to greater success in combat scenarios. 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. Support (If Any) Support for this study came from the Military Operational Medicine Research Program (MOMRP) of the United States Army Medical Research and Development Command (USAMRDC). Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the authors, and are not to be construed as official, or as reflecting true views of the Department of the Army or the Department of Defense. The investigators have adhered to the policies for protection of human subjects as prescribed in AR 70–25. The authors have no conflicts of interest to disclose.

Abstract Introduction There is a well-established connection between sleep and the immune system, and in the midst of a global pandemic, it is vital to understand the relationship between COVID-19 symptomatology and sleep. While our communities practice safety protocols, medical personnel working on the COVID-19 response effort are at high risk for exposure and contraction. This creates an urgent need to better understand whether sleep may contribute to COVID-19 symptom onset, severity, and recovery. This study examined the relationship between subjective and objective sleep during infection. Methods Fifty volunteers (age 35.15±9.97) considered high risk for COVID-19 participated in the study. The sample consisted mostly of medical personnel (93.27%) working through the pandemic. Over six months, participants completed monthly surveys and daily logs via Qualtrics. These surveys included questions about sleep, infection symptoms, COVID-19 tests and diagnoses, and mood. Wrist-worn actigraphy was collected continuously throughout the study. Sleep duration, latency, wake after sleep onset, and efficiency were processed using Philips Actiware 6.0. Actigraphy and survey data were analyzed using SPSS v. 25. Results Sixty-two percent of participants experienced infection symptoms. Those experiencing symptoms were significantly more likely to report having poorer sleep quality t(255.59)=5.78, p=<.001, poorer mood upon waking t(258.03)=6.53, p=<.001, feeling less alert upon waking t(255.61)=4.56, p=<.001, and spending more time awake at night t(2.66.98)=-7.29, p=<.001. Results showed that compared to those asymptomatic, participants with cough t(2164)=2.07, p=.039, diarrhea t(2161)=2.51, p=.012, and headache t(106.18)=7.05, p=<.001 all had significantly less total sleep time, while those with body aches spent significantly more time awake at night t(2164)=2.10, p=.036. Conclusion This preliminary examination of the data broadly suggests that medical personnel experiencing infection symptoms may have difficulty obtaining adequate sleep. Further, specific infection symptoms may share a stronger relationship with key sleep parameters than others. These findings support further testing of the bi-direction relationship between infection symptoms and sleep. Results from this research will contribute to enhancing prevention, detection, and treatment guidance related to future domestic and globally-experienced infections. Support (if any) Support for this study comes from there Military Operational Medicine Research Program of the United States Army Medical Research and Development Command.