Psychological Impact of Conflict Zone Exposure and the Mitigating Role of Physical Activity in Active-Duty Military Personnel

INTRODUCTION

Modern battlefields require physical and psychological preparation to handle the multitude of stress-inducing stimuli inherent in the combat environment [1]. Stressors could originate from diverse factors, including environmental, psychological, cognitive, emotional, and psychosocial. Understanding their impact is crucial for developing effective strategies to support military well-being [2]. In recent years, scientific research in military psychophysiology has highlighted the significant influence of stress on military personnel, primarily focusing on acute psychophysiological stress responses to continuous exposure to

stressful events [3-6]. Modern theatres of operations, characterized by their unpredictable and high-stakes nature, present unique challenges that exacerbate these challenges, with anticipatory stress—experienced even before traumatic events [7]. Continued exposure to stressors would have significant psychological consequences on the soldier, leading to chronic stress disorders [8]. The long-term consequences of such exposure often manifest in chronic stress disorders, a wide range of responses related to hyperarousal and avoidance symptoms, deeply affecting individuals. Scientific literature indicates that exposure to chronic stress predisposes individuals to severe psychiatric disorders, such as post-traumatic stress disorder (PTSD), generalized anxiety disorder, and depression. These disorders significantly lower the quality of life and negatively impact work performance and

personal relationships [9, 10]. Furthermore, chronic combat stress and life-threatening injuries are recognized as contributors to PTSD [11], making combat stress one of the most pervasive causes of PTSD among veterans and active military personnel [12].

In addition to physical and mental health challenges, sleep disorders represent a significant health concern among military personnel [13]. Sleep disruptions, such as insomnia, erratic sleep patterns, and obstructive sleep apnea (OSA), are prevalent due to operational stress, combat exposure, and the physical demands of military service [14]. These disruptions exacerbate the already stressful environment and increase the risk of psychological disorders, such as PTSD, anxiety, and depression [13]. Researchers have demonstrated a cyclical relation between poor sleep quality and the severity of mental health disorders among military personnel; for example, insomnia is both a precursor to and a consequence of PTSD, creating a vicious cycle that hampers recovery [15]. Moreover, sleep disorders like OSA are associated with elevated risk of cardiovascular disease, cognitive impairment, and reduced operational readiness [16]. This link between sleep and mental health underscores the need for targeted interventions to address both simultaneously, as untreated sleep problems could further exacerbate the psychological burden experienced by military personnel.

Understanding these psychological effects is crucial for determining effective prevention and treatment strategies. Early intervention, resilience enhancement programs, and continuous psychosocial support can mitigate the potentially catastrophic outcomes of longterm exposure to stress and stress-related disorders [17]. Among these strategies, physical activity stands out as an effective treatment for psychological pathologies [18]. Systemic physical exercise alleviates symptoms of stress, anxiety, and depression, making it a vital component of holistic military mental health strategies [19]. Research indicates that physical exercise positively affects both physical and mental health by decreasing PTSD symptoms, improving mood, and enhancing overall psychosocial resilience. It has been observed that long-term physical exercise is associated with a reduction in cortisol levels due to the development of adaptive mechanisms. In addition, engaging in physical activity helps improve sleep quality, which indirectly reduces perceived stress [20].

While previous studies have established the link between stress, sleep quality, and psychological well-being, there is limited research exploring how these relationships manifest in military populations directly exposed to armed conflict. This study addresses that gap by examining these variables in Colombian soldiers deployed in high-risk areas, an underrepresented and operationally unique population[21].

The present study aimed to analyze the effect of conflict zone exposure in psychological well-being and to analyze the role of physical activity in mitigating this effect. The initial hypothesis was that soldiers who have experienced traumatic events in conflict zones would exhibit higher stress-related parameters compared to those who have not faced such adverse events and that higher physical activity levels would correlate with improved psychological well-being.

MATERIALS AND METHODS

Participants

A total of 261 male Colombian Army military personnel were analyzed, with an average service duration of 7.49 ± 7.99 years and an average of 3.67 ± 4.60 years spent in red zones (57.09% had spent 0-1 year in red zones, while 42.91% had spent more than 1 year in red zones). The 26.44% have experienced some traumatic event in combat. The participants had an average age of 25.12 ± 6.78 years, height of 170.83 ± 12.48 cm, and body mass of 69.18 ± 10.15 kg. The military personnel were drawn from various units representing ranks ranging from Soldier to Senior Sergeant, with approximately 80% of the participants being Soldiers, while the remaining 20% held higher ranks. All the procedures and measurements were approved by CIPI/18/093, before intervention to all the military personnel, who gave their voluntary written informed consent in accordance with the Declaration of Helsinki.

Procedure

The responses from the military personnel were collected in an area outside the theater of operations. The effects of exposure to conflict zones were assessed using validated questionnaires and some quality-of-life questions that will be presented below.

a) State-Trait Anxiety Inventory (STAI). ). We used the Spanish adaptation of the STAI by Spielberger et al. (1982). The inventory consists of two subscales: state anxiety and trait anxiety, each comprising 20 items. Responses are rated on a 4-point Likert scale (1 = Not at all, 4 = Very much so), yielding scores ranging from 20 to 80 per subscale. Several items are reverse scored (e.g., items 1, 2, 5, 8, 10 for state; 21, 26, 27, 30, 33 for trait). In our sample, Cronbach’s alpha was (0.91) for state anxiety and (0.88) for trait anxiety [22].

b) Live Engagement Scale (LES). The LES evaluates the impact of life events and was adapted to Spanish by Mañas-Rodríguez et al. (2016). The scale consists of 9 items that assess behavioral engagement in activities, using a 5-point Likert scale (1 = Strongly disagree, 5 = Strongly agree). The total score ranges from 9 to 45, with higher scores indicating greater engagement. No items are reversescored. In our sample, the Cronbach’s alpha was (0.87)[23].

c) UCLA Loneliness Scale. Developed at the University of California, Los Angeles, this scale measures feelings of loneliness and social isolation. It is extensively used in research to explore the subjective experience of loneliness across various groups. It is answered on

a four-point Likert scale where 1= never and 4= always. An example item is as follows: “My social relationships are superficial.” The scale consists of 20 items rated on a 4-point Likert scale (1 = Never, 4 = Often), with total scores ranging from 20 to 80. Nine items are reverse scored (e.g., items 1, 5, 6, 9, 10, 15, 16, 19, 20). In this study, Cronbach’s alpha was (0.92) [24].

d) Acceptance and Action Questionnaire II. The AAQ II measures psychological flexibility, which involves being open to the present moment and adjusting or maintaining behaviours aligned with personal values. It consists of 10 items that are answered on a sevenpoint Likert scale, where 1= never and 7= always. An example item is as follows: “I try to suppress thoughts and feelings that I don´t like by just not thinking about them.” All items were scored in the same direction (no reversals). Cronbach’s alpha in our sample was (0.89) [25]

e) Perceived Stress Scale (PSS-14). The PSS-14 assesses the degree to which individuals perceive their life situations as stressful over a one-month period. It examines perceptions of unpredictability, uncontrollability, and overload, making it a vital instrument for understanding stress’s psychological impact. It is composed of 14 items that are answered on a five-point Likert scale, where 0= never and 4 = very often. An example item is as follows: “In the last month, how often did you feel nervous and stressed?”. Seven items are positively stated and thus reverse-scored (items 4, 5, 6, 7, 9, 10, 13). In this study, the scale demonstrated good internal consistency (α = .86) [26].

f) Sleep quality and perceived happiness were reported by the soldier, as was the amount of physical activity performed weekly by each soldier. Soldiers rated their perception of both parameters from 0 to 10 [6].

d) Soldiers responded to dichotomous questions asking if they had experienced the death of a comrade, if they had suffered war injuries, and if they had seen a comrade suffer injuries in combat [6].

e) Soldiers quantified the average number of minutes of physical activity performed per day (average of a normal week) [6].

Data analysis

For the statistical analysis, IBM SPSS Statistics Version 20 was employed to process the collected data. An independent samples t-test was utilized to compare the means of the results of the variables between military personnel who had experienced a traumatic event and those who had not. In addition, an Analysis of Variance (ANOVA) was conducted to further explore the influence of physical activity on psychological outcomes. The level of significance was set at p ≤ 0.05.

The sample size was determined based on logistical feasibility and accessibility to active military personnel during the data collection period. Although no formal a priori power analysis was conducted, the final sample of 261 participants exceeds the minimum recommendations for psychological studies using t-tests and ANOVAs with medium effect sizes (Cohen’s d ≈ 0.5) and power of 0.80 at α = 0.05. Future research should consider more rigorous power-based sampling frameworks. Regarding missing data, all questionnaires were manually reviewed upon submission to ensure completeness. Incomplete responses were excluded from the final analysis, and no imputation procedures were applied. To explore the associations between conflict exposure and psychological outcomes, we performed non-parametric Spearman correlation analyses. Specifically, correlations were computed between years of deployment in red zones and scores of sleep quality, happiness, perceived stress (PSS-14), and anxiety (STAI). In addition, traumatic exposure (coded as 0 = no, 1 = yes) was correlated with the same psychological variables. Spearman’s rho coefficients and p-values are reported. This analytical approach was selected due to the non-normal distribution of the variables and the ordinal nature of several measures.

RESULTS

Table 1 shows the differences in psychological parameters between soldiers with and without traumatic events. Individuals who have experienced trauma reported lower sleep quality, with an average score of 7.57 ± 2.11, compared to 8.39 ±1.78 for those without trauma. Similarly, the happiness rate for the trauma-exposed group was 8.10 ±1.93, which was lower than the 8.89 ±1.53 recorded for their non-traumatized peers. No other significant differences were reported in the psychological assessments. Spearman correlation analyses showed that both years ofdeployment in red zones and traumatic exposure were significantly associated with poorer sleep quality (ρ = –0.245, p < 0.001; ρ = –0.225, p = 0.0003, respectively). Traumatic exposure was also negatively associated with perceived happiness (ρ = –0.155, p = 0.012). No significant associations were observed between conflict exposure (years in red zone or trauma) and perceived stress or anxiety levels (Table 5).

STAI (State-Trait Anxiety Inventory), LET (Life Engagement Test), AAQ (Acceptance and Action Questionnaire II), PSS-14 Perceived Stress Scale

Table 2 shows the differences in psychological parameters between soldiers who spent 0-1 year and more than 1 year in a red zone. Soldiers in the more than 1-year group reported significantly lower sleep quality 7.54 ± 2.17 compared to the 0–1-year group 8.66 ± 1.56. No other significant differences were found across the other psychological measures.

STAI (State-Trait Anxiety Inventory), LET (Life Engagement Test), AAQ (Acceptance and Action Questionnaire II), PSS-14 Perceived Stress Scale

Table 3 shows that physical activity had a significant impact on the Perceived Stress Scale (PSS-14) values.

Stai (State-Trait Anxiety Inventory), LET (Life Engagement Test), AAQ (Acceptance and Action Questionnaire II), PSS-14 Perceived Stress Scale

Further analysis provided in Table 4, through a post hoc examination, showed a significant interaction based on the duration of physical activity. Soldiers who engaged in physical activity for more than 120 minutes showed substantially lower PSS-14 scores, averaging 14.05 ± 8.12, compared to those who were active for only 30 to 45 minutes, who had an average score of 18.91± 8.30. No other significant differences were reported in the psychological assessments.

PSS-14, Perceived Stress Scale

DISCUSSION

This study aimed to analyze the effects of conflict zone exposure on military psychological well-being and to analyze the role of physical activity in mitigating these effects. The results partially support both hypotheses, as soldiers with higher exposure to conflict zones have reported lower sleep quality and a lower level of happiness perceived. Furthermore, it has been observed that spending more time engaging in physical activity could reduce perceived stress. In addition to group differences, exploratory correlation analyses provided further insight into the relationship between conflict exposure and psychological outcomes. Specifically, a greater number of years deployed in red zones showed a significant negative association with sleep quality (ρ = −0.245, p < 0.001), indicating that prolonged exposure may progressively deteriorate restorative sleep. Traumatic exposure was also negatively correlated with both sleep quality (ρ = −0.225, p = 0.0003) and perceived happiness (ρ = −0.155, p = 0.012), supporting the notion that adverse operational experiences have cumulative psychosocial consequences. No significant correlations were found with perceived stress or anxiety, reinforcing the idea that these constructs may be more strongly influenced by training-related resilience mechanisms rather than direct exposure.

One of the aspects highlighted in the scientific literature regarding the effects of experiencing traumatic events in conflict zones is the association with disturbances in sleep quality. Regarding sleep quality, the data revealed that soldiers with a history of trauma showed worse sleep quality compared to those without trauma exposure due to a probable dysregulation of the sympathetic nervous system [27]. This finding aligns with previous studies indicating that individuals exposed to traumatic events often report sleep disturbances. For instance, Coelho and Costa [28] found that war veterans exhibited heightened sympathetic nervous system activation, reflected in higher catecholamine levels, which contribute to poor sleep quality. Similarly, studies on Malvinas and Vietnam war veterans highlighted the prevalence of symptoms such as insomnia, nightmares, and difficulty falling asleep [29, 30]. These disorders may be due to cumulative stress associated with exposure to combat zones, which exacerbates sleep problems even in the absence of traumatic events. Comparable findings have been observed in other professional groups working in highly demanding and stressful conditions, such as healthcare workers [31] and police officers [32], where cumulative stress negatively affects sleep quality. Like the findings on sleep quality, soldiers with traumatic experiences reported lower perception of happiness. A longer experience in combat zones and accompanied by traumatic moments has a psychosocial impact on the soldier, reducing the quality of life and happiness [33]. Previous researchers with Peruvian reservists exposed to conflict showed that low happiness levels were predominant in 49% of participants, with PTSD symptoms reported in 67% [34]. Along the same lines, veteran soldiers deployed in long-term conflict zones such as the Iraq or Afghanistan wars showed a decrease in perception of happiness, or quality of life, due to the traumatic situations experienced in conflict zones [35].

While soldiers with experience in conflict zones showed diminished perceptions of happiness and sleep quality, their evaluations of stress and anxiety revealed no significant differences. State anxiety levels, as measured by the STAI, were low across the sample and consistent across both groups, suggesting a balanced commitment to life despite exposure to traumatic experiences. Similarly, perceived stress, as measured by the PSS-14, showed no significant differences between groups, with both reporting moderate levels of stress within the normative range. These findings suggest that, while traumatic experiences may significantly impact specific domains such as sleep quality and happiness, their effect on perceived stress and anxiety may be less pronounced among military personnel. This pattern was further confirmed in the correlation analyses, which showed no significant association between either years in red zones or traumatic exposure with stress (PSS-14) or anxiety (STAI). This suggests that, while sleep and emotional wellbeing appear to be sensitive to cumulative operational exposure, perceived stress and anxiety may be more strongly buffered by military training, habituation, and unit cohesion. This resilience can likely be attributed to the psychological preparation inherent in military training, which equips soldiers to manage stress effectively through exposure to simulated high-pressure scenarios and resilience-building strategies [36, 37]. Previous studies have highlighted the role of psychological training in enhancing coping mechanisms and emotional regulation, contributing to the ability of military personnel to maintain moderate stress levels and low anxiety even in challenging circumstances [38]. This preparation is particularly evident in professional soldiers, who, because of their training and experience, may be less inclined to report feelings of stress or anxiety. These findings are consistent with our correlation analyses, which demonstrated that both traumatic exposure and longer periods in red zones were moderately associated with poorer

sleep quality. The additional negative correlation between traumatic events and happiness reinforces previous observations that repeated exposure to threatening environments progressively diminishes subjective well-being.

This preparation of professional soldiers is reflected in their high psychological flexibility and low levels of perceived loneliness. Psychological flexibility, as measured by the AAQ-II, was notably high in both groups compared to non-clinical populations, indicating their ability to adapt to changing circumstances and manage difficult emotions effectively. This adaptability is likely fostered by military training, which emphasizes problem-solving, emotional regulation, and resilience. Similarly, loneliness levels, assessed through the UCLA Loneliness Scale, were remarkably low across both groups, significantly below the normative average for the general population. This finding highlights the strong camaraderie and social support inherent in military environments, which act as protective factors against isolation and stress. Previous studies support this, showing that cohesive military units provide both emotional and practical support, fostering resilience and enabling soldiers to cope better with adversity [39, 40].

Regarding the well-being and mental health of military personnel, it has been shown that physical activity has a significant impact on reducing perceived stress among the participants in this study. Soldiers who engaged in physical activity for more than 120 minutes reported notably lower stress levels compared to those who exercised for only 30–45 minutes. This finding highlights the role of regular physical activity as a protective factor against stress, aligning with previous research showing that physical activity decreases stress, anxiety, and depression [41]. Furthermore, physical activity is known to improve mood, boost self-confidence, enhance selfesteem, and alleviate sleep disorders, contributing to overall mental well-being [42]. The observed reduction in perceived stress among soldiers who engage in increased physical activity is consistent with that observed in previous studies [43]. In addition, it has been shown that higher levels of exercise during periods such as university examinations mitigated the psychophysiological effects of stress, supporting the notion that prolonged physical activity acts as a buffer against stress [44]. It would be interesting to analyze the effects of operative training on psychological well-being.

This study contributes to the literature by highlighting how established associations between stress, sleep, and emotional well-being play out in a real-world, high-risk context. Unlike general civilian samples, this population faces chronic exposure to violence and operational demands, which may shape their psychological resilience and influence the way stress-related symptoms are experienced and reported [45].

Practical applications

Understanding the impact of traumatic events on active-duty military personnel is highly valuable for preventing potential consequences. To improve the psychological indicators evaluated in soldiers, it is essential to design a comprehensive psychosocial intervention that addresses the impact of trauma, chronic stress, and prolonged service conditions in conflict zones.

The psychological well-being of active-duty military personnel is significantly affected by exposure to trauma, chronic stress, and prolonged service in conflict zones, necessitating comprehensive psychosocial interventions. Improving sleep quality through Cognitive Behavioral Therapy for Insomnia (CBT-I), relaxation techniques such as diaphragmatic breathing and mindfulness, and structured physical activity programs can mitigate stress and enhance resilience. Additionally, fostering emotional intelligence and promoting recreational activities can contribute to stress regulation and increased perceived happiness levels. Access to psychological support, including exposure therapies and Eye Movement Desensitization and Reprocessing (EMDR), is essential for addressing trauma-related symptoms, particularly those associated with PTSD, and improving sleep parameters. Institutional commitment, including leadership awareness, rotation policies, and expanded mental health resources, is crucial to the success of these interventions, ultimately strengthening soldiers’ resilience and coping mechanisms in high-stress environments.

Limitations and future research directions

This study has contributed to the evidence base, but not without its limitations. The cross-sectional design limits inferences about causality. Additionally, the focus on this specific sample of military personnel in Colombia limits the generalizability of the findings. Future research could focus on conducting longitudinal studies to evaluate the long-term effects of traumatic events, including the role of physical activity. Additionally, physical training and adaptations should include specific interventions that consider the military unit’s situation and operational context, which might lead to better results. Future studies should explore the role of other factors, such as social support and institutional policies, in mitigating the adverse effects associated with trauma and chronic stress.

CONCLUSION

Soldiers with greater exposure to combat zones reported lower perceptions of sleep quality and happiness. However, engaging in physical exercise is associated with reduced stress, potentially serving as a protective factor against stress-related disorders.

Conflicts of interest and sources of funding

The authors declare no conflict of interest. This research received no external funding.

Authors’ contribution

Conceptualization, Clemente-Suárez, and Curiel-Regueros; methodology Clemente-Suárez, and Curiel-Regueros; formal analysis, Curiel-Regueros; investigation, ClementeSuárez, and Curiel-Regueros; resources, Clemente-Suárez; data curation, Clemente-Suárez, and Curiel-Regueros; writing—original draft preparation, Curiel-Regueros and Sánchez-Conde; writing—review and editing, Curiel-Regueros, Martínez-González, and Sánchez-Conde; visualization Martínez-González and Sánchez-Conde; supervision, Clemente-Suárez. All authors have read and agreed to the published version of the manuscript.

Ethics approval and consent to participate

The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Universidad Europea de Madrid (CIPI/18/093) Patient consent for publication Informed consent was obtained from all subjects involved in the study.

References:

1. Clemente-Suárez VJ, Robles-Pérez JJ. Psycho-physiological response of soldiers in urban combat. An Psicol. 2013;29:598–603.
2. Vergara GA. Agentes estresores: el enemigo oculto de las fuerzas militares. Rev Ensayos Militares. 2021;7(2):85–100.
3. Bustamante-Sánchez A, Clemente-Suárez VJ. Psychophysiological response in night and instrument helicopter flights. Ergonomics. 2020;63:399–406.
4. Clemente-Suárez VJ, Palomera PR, Robles-Pérez JJ. Psychophysiological response to acute high-stress combat situations in professional soldiers. Stress Health. 2018;34(2):247–252.
5. Merchan A, Clemente-Suárez VJ. Psychophysiological modifications in an assault infantry manoeuvre using chemical, biological, radiological and nuclear personal protective equipment. BMJ Mil Health. 2020;166(2):62–66.
6. Vicente-Rodriguez M, Clemente-Suárez VJ. Psychophysiological anxiety response of a rescue helicopter crew in a crane rescue manoeuvre. BMJ Mil Health. 2021;167(6):413–417.
7. Curiel-Regueros A, Fernández-Lucas J, Clemente-Suárez VJ. Psychophysiological stress status of soldiers prior to an operative deployment. Int J Environ Res Public Health. 2022;19(20):13637.
8. Clemente-Suárez VJ, Robles-Pérez JJ. Respuesta orgánica en una simulación de combate. Sanid Mil. 2012;68(2):97–100. doi:10.4321/S1887-85712012000200006.
9. Hare OA, Wetherell MA, Smith MA. State anxiety and cortisol reactivity to skydiving in novice versus experienced skydivers. Physiol Behav. 2013;118:40–44.
10. Nindl BC, Jones BH, Van Arsdale SJ, Kelly K, Kraemer WJ. Operational physical performance and fitness in military women. Mil Med. 2016;181(1 Suppl):50–62. doi:10.7205/MILMED-D-15-00382.
11. Koenig HG, Youssef NA, Smothers Z, et al. Hope, religiosity, and mental health in US veterans and active duty military with PTSD symptoms. Mil Med. 2020;185(1-2):97–104.
12. Miller MW, Lin AP, Wolf EJ, Miller DR. Oxidative stress, inflammation, and neuroprogression in chronic PTSD. Harv Rev Psychiatry. 2018;26(2):57–69.
13. Mysliwiec V, Gill J, Lee H, et al. Sleep disorders in US military personnel. Chest. 2013;144(2):549–557.
14. Taylor MK, Hilton SM, Campbell JS, et al. Prevalence and mental health correlates of sleep disruption among military members serving in a combat zone. Mil Med. 2014;179(7):744–751.
15. Bramoweth AD, Germain A. Deployment-related insomnia in military personnel and veterans. Curr Psychiatry Rep. 2013;15:1–8.
16. Mantua J, Bessey A, Sowden WJ, et al. Environmental barriers to obtaining adequate sleep in the military operational context. Mil Med. 2019;184(7-8):e259–e266.
17. Robinson SJ, Sünram-Lea SI, Leach J, Owen-Lynch PJ. Acute stress effects on working memory and cortisol. Stress. 2008;11(2):115–124.
18. Chen KJ, Yang CC, Chiang HH. Coping strategies, resilience and well-being in military personnel. J Med Sci. 2018;38(2):73–80.
19. Martín-Rodríguez A, Gostian-Ropotin LA, Beltrán-Velasco AI, et al. Sporting mind: interplay of physical activity and psychological health. Sports. 2024;12(1):37.
20. Oppizzi LM, Umberger R. Effect of physical activity on PTSD. Issues Ment Health Nurs. 2018;39(2):179–187.
21. Rosenbaum S, Vancampfort D, Steel Z, et al. Physical activity in PTSD treatment: systematic review. Psychiatry Res. 2015;230(2):130–136.
22. Spielberger CD, Gorsuch RL, Lushene RE, Cubero NS. STAI manual. Madrid: TEA; 1999.
23. Chaudhury S, Srivastava K, Raju MSVK, Salujha SK. Life events scale for armed forces personnel. Indian J Psychiatry. 2006;48(3):165–176.
24. Russell DW. UCLA loneliness scale (version 3). J Pers Assess. 1996;66(1):20–40.
25. Bond FW, Hayes SC, Baer RA, et al. Acceptance and Action Questionnaire-II. Behav Ther. 2011;42(4):676–688.
26. Clemente-Suárez VJ. Multidisciplinary intervention in anxiety and depression disorder. Physiol Behav. 2020;219:112858.
27. van Liempt S, Arends J, Cluitmans PJM, et al. Sympathetic and HPA activity during sleep in PTSD. Psychoneuroendocrinology. 2013;38(1):155–165.
28. Maia LACR. Bases neurobiológicas del estrés post-traumático. An Psicol. 2010;26(1):1–10.
29. Helzer JE, Robins LN, McEvoy L. PTSD in the general population. N Engl J Med. 1987;317(26):1630–1634.
30. Leguizamón L, Correché MS, Gómez L, Martínez V. Efectos psicosomáticos en ex combatientes. Rev Diálogos. 2012;3(1):45–57.
31. Weaver MD, Vetter C, Rajaratnam SMW, et al. Sleep disorders and safety outcomes. J Sleep Res. 2018;27(6):e12722.
32. Rajaratnam SMW, Barger LK, Lockley SW, et al. Sleep disorders in police officers. JAMA. 2011;306(23):2567–2578.
33. Páez D, Bilbao MA, Javaloy F. Del trauma a la felicidad. Pract Psicol Posit. 2008:159–202.
34. Baldeon Leon LL. Agresión, estrés, postrauma y felicidad en reservistas de Huánuco. 2018.
35. Lester PB, Stewart EP, Vie LL, et al. Happy soldiers are highest performers. J Happiness Stud. 2022;23(3):1099–1120.
36. Szivak TK, Kraemer WJ. Physiological readiness and resilience. J Strength Cond Res. 2015;29:S34–S39.
37. Thompson MM, McCreary DR. Enhancing mental readiness in military personnel. In: Military life. Vol 2. 2006. p.54–79.
38. Thomas JL, Adler AB, Wittels P, et al. Psychological and physical demands in military training. Mil Med. 2004;169(7):526–530.
39. Dalal S, Singh S. Psychological flexibility and well-being in defence personnel. Psychol Hub. 2023;40(3):67–84.
40. Peterson AL, Moore BA, Evans WR, et al. Psychological flexibility training trial design. Front Psychiatry. 2024;14:1299532.
41. Barbosa S, Urrea A. Sport and physical activity in mental health. Rev Katharsis. 2018;25:141–159.
42. Pérez Ponce FS. Actividad física y estrés en personal asistencial. 2023.
43. Cortes Álzate AM, Zapata Cabrera Y. Trastorno de estrés postraumático en fuerzas militares. 2022.
44. Wunsch K, Kasten N, Fuchs R. Physical activity and sleep quality during stress. Nat Sci Sleep. 2017:117–126.
45. Tait JL, Drain JR, Corrigan SL, et al. Military training stress and hormone response. PLoS One. 2022;17(3):e0265121. doi:10.1371/journal.pone.0265121.