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.

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.

0189 Sleep Duration and Subjective Resilience to Sleep Loss Predict Functional Impairment in Elite Infantrymen During Military Training

Introduction

Insufficient sleep during military operations is detrimental to cognition, physical performance, and general health outcomes. However, there is evidence of inter-individual differences in resilience to sleep loss. Therefore, some Soldiers may be more resilient to the effects of sleep loss than others. This study examined the relationship between sleep duration, resilience, and Soldier well-being during a deployment-readiness training event.

Methods

Seventy-six male Soldiers (aged 25.7±4.0y) from the 75th Ranger Regiment participated while undergoing a two-week training exercise. Surveys were administered at the completion of training and queried subjective measures of sleep duration during training, functional impairment (Walter Reed Functional Impairment Scale), and resilience to sleep loss (Iowa Resilience to Sleepiness Test; iREST). The independent relationships between sleep duration, resilience to sleep loss, and functional impairment were assessed using linear regressions. The interaction between sleep duration and resilience to sleep loss was assessed using SPSS Process (Model 1).

Results

Shorter sleep duration during training predicted higher functional impairment at the end of training (B=-.71, p=.001). Less resilience to sleep loss also predicted higher functional impairment (B=.07,p=.004). An interaction between sleep duration and resilience predicted Soldier impairment (R2 change: .06; F(1,68)=.17,p=.03). Individuals with both shorter sleep duration during training and less resilience had the highest functional impairment. Those with more sleep, and those with high resilience and less sleep, both had lower functional impairment.

Conclusion

This study suggests the iREST can be used as a quick, subjective screening tool to indicate who may be most vulnerable to the effects of sleep loss. Identifying individual resilience to sleep loss may be useful in the military context for prescribing sleep strategies before and during missions in order to enhance Soldier readiness and performance.

Support

Support for this study came from the Military Operational Medicine Research Program (MOMRP) of the United States Army Medical Research and Development Command (USAMRDC).

Isolation of the CD7 gene from the DNA of transfected L cells

Using DNA from L cells which expressed high levels of the CD7 (Leu-9 or HuLy-m2) antigen obtained after two cycles of transfection, a genomic library was constructed in the lambda phage Charon 4A. Recombinant clones containing the gene coding for this antigen were identified by first screening the library with both the HSV-tk gene and a probe detecting the human repetitive (Alu) sequences. DNA from 10 tk+ and 12 Alu+ recombinant clones was used to transfect L cells which were analyzed for the cell-surface expression of CD7 either early (48-72 h posttransfection) or later when hypoxanthine aminopterin thymidine-resistant colonies were obtained. Transfection with either Alu+ or tk+ recombinant phages led to transient early expression of CD7, and stable CD7+ transfectants were also established. Thus the CD7 gene has been isolated in a number of clones in association with either the Alu repetitive sequence or with the HSV-tk gene; the insert size in one of the genomic clones was 13.5 kb.

Identification of two forms of the Ly-6.2 antigen showing differential expression

A monoclonal antibody to the Ly-6.2 specificity, defined by strain and tissue distribution, was used to identify the cellular antigens of lymphocytes and tumor cell lines. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of immune precipitates demonstrated that the Ly-6.2 antigen on the surface of thymus and the T lymphoma EL-4 was a protein of 34 kd, whereas spleen cells showed two Ly-6.2 molecules of 34 kd and 56 kd. In vitro translation of EL-4 T-lymphoma poly A+ RNA followed by immunoprecipitation showed the synthesis of two Ly-6.2 precursor polypeptides. These two precursors were translated from separable mRNA molecules; the larger encoded a 54 kd polypeptide, while the second, smaller one translated a 36 kd polypeptide. Thus, the T lymphoma EL-4 contains two distinct mRNA, but only one is seen on the surface, while spleen cells contain and translate both mRNAs and both surface forms are detected. What determines the utilization of the two mRNAs and the surface expression of the two different proteins in the different tissues is not known. Whether the two mRNAs are the transcripts of one gene or arise by transcription of two separate but closely linked genes remains to be determined.