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 non-military populations due to a number of occupational, cultural, and psychosocial factors (e.g., continuous operations, stress, 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 = 2296, 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 [hours]) 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 even military-wide policy changes regarding sleep and HRB.
BackgroundUS 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.MethodsSeventy-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.ResultsSoldiers 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.ConclusionOptimising 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.
Introduction Sleep loss that is inherent to military operations can lead to cognitive errors and potential mission failure. Single Nucleotide Polymorphisms (SNPs) allele variations of several genes (COMT, ADORA2A, TNFa, CLOCK, DAT1) have been linked with inter-individual cognitive resilience to sleep loss through various mechanisms. U.S. Army Soldiers with resilience-related alleles may be better-suited to perform cognitively-arduous duties under conditions of sleep loss than those without these alleles. However, military-wide genetic screening is costly, arduous, and infeasible. This study tested whether a brief survey of subjective resilience to sleep loss (1) can demarcate soldiers with and without resilience-related alleles, and, if so, (2) can predict cognitive performance under conditions of sleep loss. Methods Six SNPs from the aforementioned genes were sequenced from 75 male U.S. Army special operations Soldiers (age 25.7±4.1). Psychomotor vigilance, response inhibition, and decision-making were tested after a night of mission-driven total sleep deprivation. The Iowa Resilience to Sleeplessness Test (iREST) Cognitive Subscale, which measures subjective cognitive resilience to sleep loss, was administered after a week of recovery sleep. A receiver operating characteristic (ROC) curve was used to determine whether the iREST Cognitive Subscale can discriminate between gene carriers, and a cutoff score was determined. Cognitive performance after sleep deprivation was compared between those below/above the cutoff score using t-tests or Mann-Whitney U tests. Results The iREST discriminated between allele variations for COMT (ROC=.65,SE=.07,p=.03), with an optimal cutoff score of 3.03 out of 5, with 90% sensitivity and 51.4% specificity. Soldiers below the cutoff score had significantly poorer for psychomotor vigilance reaction time (t=-2.39,p=.02), response inhibition errors of commission (U=155.00,W=246.00,p=.04), and decision-making reaction time (t=2.13,p=.04) than Soldiers above the cutoff score. Conclusion The iREST Cognitive Subscale can discriminate between those with and without specific vulnerability/resilience-related genotypes. If these findings are replicated, the iREST Cognitive Subscale could be used to help military leaders make decisions about proper personnel placement when sleep loss is unavoidable. This would likely result in increased safety and improved performance during military missions. Support (if any) Support for this study came from the Military Operational Medicine Research Program of the United States Army Medical Research and Development Command.
Introduction U.S. Army Reserve Officer Training Corps (ROTC) Advanced Camp (AC) is a 29-day training that assesses military skills and leadership potential in college students training to become Commissioned Officers (i.e. Cadets). Military trainings are widely known to disrupt normative sleep. Additionally, operational sleep disruption is linked to performance decrements. This study examined the ability for objective and subjective sleep during ROTC AC to predict Cadet performance. Methods One hundred and fifty-nine ROTC Cadets (age 22.06±2.49 years; 76.1% male) wore an actiwatch device continuously for 29 days during AC. Paper surveys administered at the end of AC captured subjective sleep metrics during the training. ROTC instructors evaluated Cadet performance and provided scores of overall class rank and summary performance. Multiple and ordinal linear regressions assessed the predicative utility of subjective (sleep duration [SD]; Global score [Global] from the Pittsburgh Sleep Quality Index) and objective (Total Sleep Time [TST]; Sleep Efficiency [SE]; Sleep Latency Onset [SOL]; Wake After Sleep Onset [WASO] from actigraphy) sleep on performance. Results The interaction of SD and Global, when controlling for age and gender, significantly predicted increased Cadet rank, F(4,153) = 3.09, p = 0.018. Models testing the prediction of SD and Global on summary performance score were non-significant. Further, regressing of both Cadet rank and summary performance individually on objective sleep metrics, when controlling for age and gender, resulted in non-significant findings. Conclusion Subjective and objective sleep showed no significant individual predictive utility on performance. However, the combined subjective model significantly predicted that Cadets who slept worse (lower SD; higher Global) during AC received a lower rank at the end of the training. These findings suggest there may be a unique combined predictive utility of subjective sleep on performance when compared to the predictive power of individual variables. Therefore, subjective sleep may be better for predicting operational performance than objective sleep. Future analyses will refine these models and examine how performance on individual AC events may be influenced by sleep. Support for this study came from the Military Operational Medicine Research Program (MOMRP) of the United States Army Medical Research and Development Command (USAMRDC). Support (if any):
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.
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