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Effects of Psychological Stress on the Immune System


For a long time, investigative studies have shown that mental stress affects the immune system’ reactions, including erythrogenic activities, the ability to recuperate from injuries, and responses to contagious disease-causing micro-organisms. Nonetheless, the ability to handle stressful situations differs from one individual to another. The variations occur due to an individual’s perspectives about tense situations, temperament, and cumulative inauspicious circumstances in a person’s life. Adverse occurrences reshape the extent to which mental distress negatively impacts the human body’s defence mechanism. Biologically, there exists some credible complex process that explains how prolonged psychological pressure results to grave medical outcomes such as diabetes and heart diseases.

Mental stress is a broad concept that consists of challenging events, and the physiological or psychological responses to such experiences. Human beings, among all other species, exhibit a disease-resistance mechanism that reacts to challenging situations. Generally, an immune system is comprised of biological cells, fats and amino acids, body parts and tissues that function collaboratively to offer an anatomical defence against pathogens. Various aspects of the human defence mechanism have been associated with stress. The features of the biodefence system are what ignite the specific responses that are observed when stress occurs. As such, stress has a measurable impact on the body’s defence structure, which then affects health outcomes because of the relationship that exists between the nervous system and human immunity.

In assessing the association between psychological stress and immunology, it is important to establish different researches that have been done on stress and immune responses. There has been limited evidence-based research to show the existence of a relationship of any nature over the past years. Immune responses that different studies have investigated concerning stress include responses to infectious agents, inflammatory processes; wound healing, and other immune challenges such as vaccinations, autoimmunity (Khalil et al., 2020). Therefore, immune responses are pegged on natural immunity which can be affected by stress.

People can differ in how they cope with stressors in their lives. The variance can be attributed to how the individuals perceive stress, depressive symptoms such as mood, in addition to unpropitious life incidents (Khalil et al., 2020). The change in life’s value arises since mental stress wields an unfavourable effect on an individual’s defence structure. Remarkably, exact variations occur in the scope of individuals’ stress behaviour. The respective variations in trauma morphology are, inclusive of other body organs, associated with the brain which functions to appraise the stressors (O’Daly, 2020). Moreover, the brain modulates the response of the defence mechanism’s response to bodily harm and possible dangers. Therefore, stress is a body’s mechanism of reacting to some pressure or harm as well as a protection strategy in case of any danger. Whether the threats are real or imagined, the human body initiates the spontaneous process known as the fight-or-flight reaction (Khalil et al., 2020). Accordingly, any healthy human being possesses the preconditioned stress response mechanism.

The stress response mechanism is vital as it concerns the wellness of an individual. When it operates properly, it enables one to stay focused, energetic and alert. In the case of an extremity, psychological strain can ensure one’s survival through giving supplemental energy to safeguard oneself, for instance, impelling a person to brake suddenly to avert a motor accident. Contrarily, at some point, stress ceases to be beneficial and begins to cause serious destruction to one’s wellbeing, disposition, productiveness, social relations, and the general value of life (Seiler et al., 2020). At this particular point, the stressor is said to have exceeded the person’s recognizable capacity to subsist and will therefore culminate in psychophysiological imbalance. In addition, specific facets of any circumstance are associated with considerable stress reactions, such as magnitude, vigour, manageability, and recurrence of the stress-related events. Corporeal response to mental anguish is sometimes recognized even after subjection to the indistinguishable stressful incident. Without a doubt, stress can be useful and also harmful when it suppresses the human capacity to handle events that may be depressive.

Understandings of the relationship between stress and body’s defence mechanism’s reaction have metamorphosed over years. According to Khalil et al. (2020), lymphatic shrinkage resulted in a preliminary paradigm whereby stress was widely viewed as a cause of the dysfunction to the immune system. Early scientific researches supported this model, claiming that chronic forms of stress were chaperoned by diminishing innate destructive cell noxiousness, repressed phagocyte multiplicative reactions added to debilitated bodily actions to immunisation (Khalil et al., 2020). These kinds of declined reactions type were associated with the increased incidences of contagious and cancerous ailments that were exhibited by chronically stressed persons. Explicitly, it was established that mental stress weakens the immune system of an individual thereby increasing susceptibility to diseases.

Stress Results in Inflammation and Other Illnesses

Various research studies attribute inflammation effects with major stressful events. For instance, some research studies have found out that caring for the loved ones with the chronic medical conditions such as dementia is frequently characterized by great life challenges and isolation (Holmes and Rahe, 1967, as cited in, Seiler et al., 2020). The stress related to caregiving is then associated with intensification of typical age-related increases in serum levels of interleukin (IL-6) and C – reactive protein (CRP) (Gouin et al., 2012 as cited in, Seiler et al., 2020). As such, the studies provide basis through which poor health may be linked with stress. Considerably, the death of a loved one is regarded as one of the most stressful events in life (Holmes and Rahe, 1967, as cited in, Seiler et al., 2020). Moreover, another research connects bereavement with increased inflammation in human (Cohen et al., 2015 as cited in, Seiler et al., 2020). Higher levels of inflammatory chronic inflammatory conditions such as diabetes, cardiovascular diseases and cancer are cited as some of the diseases that can be suffered by a bereaved person within the three years after the spouse’s death (Stahl et al., 2016 as cited in, Seiler et al., 2020). Notably, the major heart diseases can be attributed to inflammation that exacerbates to the conditions. Clearly, stressful social events have a greater impact on an individual’s wellbeing that when not checked result to killer diseases.

Interestingly, the immune system is conditioned to rid the body of any form of pathogen because of its negative effect. When someone is stressed, the immune system’s potentiality to destroy antigens is reduced, hence the individual’s vulnerability to infections increases (Seiler et al., 2020). As a result, the person fails to resist strong urges to engage in unhealthy behaviours that are detrimental such as drinking alcohol and excessive smoking of cigarettes. More so, stress is associated with headaches, infectious diseases such as influenza, heart diseases, diabetes, asthma, and gastric ulcers (Seiler et al., 2020). In sum, stress has a negative effect, not only on the immune system but also on health outcomes.

Effect of Stress on Illnesses Occurrences

Stress-related infections occur as a response to a weakened immune system. It means that whether one has a natural or adapted immunity, the person possesses resistance to pathogens, illnesses, or maladies and concurrently exhibit reliable forbearance in averting hypersensitivity and sarcoidosis (Baumeister et al., 2016). Two significant tracks contribute to immune responses control and they are the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS) (O’Daly, 2020). Therefore, if a person experiences a stressful situation, the brain actuates the sympathetic-adrenal medullary (SAM) and HPA axes, which prompt the secretion of hormones that influences immune regulation (O’Daly, 2020). Among the hormones that are produced include hydrocortisone, adrenocorticotropic hormone (ACTH), lactotropin, and adrenaline (O’Daly, 2020). Research shows that prolonged emotional trauma represses or decontrols natural or acquired defence systems’ reactions by altering of the types of cytokine balances, thereby reducing the impacts of phagocytes and lymphocytes on immune system (Seiler et al., 2020). While acute inflammation remains to be a flexible response to actual harms and diseases, chronic sensational reactions are calamitous to wellbeing. Undeniably, inflammatory responses to stress and other physical harms are inevitable, and their dangers lie in the intensities and periods of occurrences.

Stress Impact on Nervous System

The effect of stress on the nervous system is established from the role of sympathetic nervous system in immune response. Aside from stress-related glucose-corticoid (GC) hormones that regulate immune functions, there is also a neurotransmitter, noradrenaline that performs the same function (O’Daly, 2020). More specifically, catecholamines induce cell multiplication during an antigen attack, helping in the production of cytokine and antibodies, cytolytic activity, and transport of the cells. Most frequently, catecholamines perform conjointly with the stimulation of the HPA axis (O’Daly, 2020). Adrenal medulla cells produce and release adrenaline hormones composed of epinephrine and norepinephrine. Notably, sympathetic nerve fibres secret norepinephrine in quantities that are proportionate to attacked tissues. Scientific investigations have proven that body can be provided with a boost in tackling any immediate threat if catecholaminergic systems are acutely activated (O’Daly, 2020). Illustratively, the most immediate effect of stress-induced norepinephrine and epinephrine is the increased pulse rate and plasma circulation in mammalian skeletal muscles. Plainly, it is psychological stress that leads to the flight-and-fight response in humans through the intervention of SNS.

Further, there is an effect of long-term activation of SAM to immune regulation and overall health. If the SAM is chronically triggered, epinephrine and norepinephrine can dysregulate immune function (O’Daly, 2020). A connection between SNS to the body’s resistance system is based on the findings that noradrenergic sympathetic nerve fibres move out of the central nervous system (CNS) to all major and minor lymphoid organs (Khalil et al., 2020). The adrenal medulla secrets epinephrine that moves in a circuit and sticks to specific adrenergic sensory receptors, causing the same results as those of direct sympathetic nervous activation. With this explanation, there exists a direct link between SNS and the immune system.

Effects of Contextual Stress Factors in Immune Function

Aside from stressful life events, there exist some contextual factors that are stress-related, which possess a measurable influence on the disease-resistance mechanism. A good example of such a factor is an adverse experience that was encountered by an individual (Ehrlich et al., 2016). In fact, having some stress-related sicknesses such as depression, cardiovascular disease, and cancer are traced to early adversities (Zion-Guest et al., 2012 as cited in, Seiler et al., 2020). Baumeister et al. (2016) have stated that the combination of acute and chronic psychic stress encountered throughout an individual’s infancy years is also known to show prolonged neurophysiological results and raises one’s susceptibility to diseases. Another important outcome of prolonged mental stress at infancy stages is that the exposure might alter behavioural and anatomical reactions to severe and immedicable stresses in maturity. With alterations in the anatomical and behavioural responses, it means that the immune system is compromised.

An additional contextual factor that is thought to be stress-related and linked with the immune response is pregnancy. The association with psychoneuroimmunology is premised on the observation that the antenatal phase is a vital period for the development of the nerves in a foetus. This is because there is a susceptibility at the time and various kinds of stress exposures have been established to induce extended effects on brain advancement and behaviours (Christian, 2012, as cited in Seiler et al., 2020). Motherly emotional stress during the pregnancy period is linked with dangers such as maternal health and birth results, in addition to infant-related outcomes (Christian, 2015, as cited in, Seiler et al., 2020). Indeed, the pregnancy period is a delicate moment for the life of the mother because any little exposure to the stressor may cause irreversible harm to both the mother and the unborn child.

In addition, age is specified as a distinctive factor that determines the functioning of the human defence mechanism. Some researchers have found that prolonged trauma can repress and cause dysfunction of the immune system hence resulting in immunosenescence, which is the loss of immune function (Mathur et al., 2016). Typically, the condition occurs in elderly individuals, leaving these people more exposed to illnesses (Mathur et al., 2016). Elderly individuals aged above 65 years possess multiple elevations in transmitted quantities of proinflammatory cytokines, for example, interleukin-6 and tumour necrosis factor (TNF) (Michaud et al., 2013, as cited in Seiler et al., 2020). The cytokines repress the functions of immune-defensive cells and disrupt the body’s capacity to safeguard itself against pathogens. Certainly, chronic stress is the main cause of dysfunctional immune systems in elderly people, and it again exposes them to more acute stress and other sicknesses.


In summary, psychological stress has a great effect on the immune system, which in turn impacts health conditions because of the interrelationship that exists between the nervous systems and immune systems. Little researches have been undertaken to study the relationship between psychological stress and immune response. Nonetheless, people have continued to have varied perceptions about the stress itself. On the positive side, stress as a response mechanism is crucial in providing an individual with focused energy to stay alert in case of any stressors. However, stress reduces the body’s ability to rid itself of any disease-causing pathogens.

Scientific assessment of the immune system helps in understanding how it works in defending the body against pathogens. An individual’s body system is conditioned to fight antigens naturally. Chronic activation of SAM helps in regulating immune function and general health. The disease-fighting mechanism depends on the nervous system that coordinates sensory information between body cells. Additionally, stress’ effect on immune response cannot be studied in isolation but within the context of other factors such as age, pregnancy, and adverse childhood experiences. Pregnancy is a critical factor because it is a period characterised by increased vulnerability to the effects of even low–levels of stress.


Baumeister, D., Akhtar, R., Ciufolini, S., Pariante, C., & Mondelli, V. (2016). Childhood trauma and adulthood inflammation: A meta-analysis of peripheral C-reactive protein, interleukin-6 and tumour necrosis factor-α. Molecular Psychiatry, 21(5), 642-649.

Ehrlich, K., Miller, G., & Chen, E. (2016). Childhood adversity and adult physical health.

Khalil, A., Nasr, R., & Enar, R. (2020). Relationship between stress, immune system, and pandemics of coronaviruses’ COVID19: Updates narrative review. European Journal of Molecular & Clinical Medicine, 7(10), 995–1008.

Mathur, M., Epel, E., Kind, S., Desai, M., Parks, C., Sandler, D., & Khazeni, N. (2016). Perceived stress and telomere length: A systematic review, meta-analysis, and methodologic considerations for advancing the field. Brain, Behaviour, and Immunity, 54, 158-169.

O’Daly, J. (2020). Sympathetic, parasympathetic and enteric nervous systems: Autonomic, enteric nervous Systems. LAP LAMBERT Academic Publishing.

Seiler, A., Fagundes, C., & Christian, L. (2020). The Impact of Everyday Stressors on the Immune System and Health. In Choukèr A. (Eds), Stress Challenges and Immunity in Space (pp.71-92). Springer, Cham.

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StudyKraken. "Effects of Psychological Stress on the Immune System." February 11, 2023.


StudyKraken. 2023. "Effects of Psychological Stress on the Immune System." February 11, 2023.


StudyKraken. (2023) 'Effects of Psychological Stress on the Immune System'. 11 February.

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