The Physiological Effects of Stress on the Human Body


Have you ever felt so stressed that it got you sick?

It is a wide-known fact, already regarded as common sense, that too much stress can be detrimental to our health. Not only does exposure to it affect our behavior and vice-versa, it also affects our body, specifically our nervous and immune systems. Here is the analysis of the process.

The General Adaptation Syndrome

Austrian-Canadian endrocrinologist Hans Selye was the founder of the field of research concerning stress and its effects on the human body. He studied the sequence of events experienced by the body during stress adaptation, called the general adaptation syndrome (GAS). According to Selye, the body goes through three stages or responses during stress:

  1. Alarm: Upon the initial awareness of a stressor, the parasympathetic nervous system (PSNS), which triggers the fight-or-flight response, kicks in.
    • Adrenal glands release stress hormones that increase heartbeat, blood pressure, and blood sugar. This leads to a sudden adrenaline rush i.e. a burst of temporary extra energy to aid the body in dealing with the stress.
    • The goosebumps you feel and the heightened reaction time are further effects of the energy burst during alarm.
  2. Resistance: As long as the stressor is present, the body will attempt to fight off or resist it by entering into sympathetic division activity. This stage will continue until the stressor goes away or all of the organism’s resources run out, whichever happens first.
    • Sympathetic division activity prepares the body for more energy output and protects it from harm. Digestion decelerates, pupils dilate, and the effects of the previous stage continue, albeit to a lessened degree, and the organism will feel more relaxed.
    • Sympathetic division is the emergency division of the autonomic nervous system (ANS), a division of the peripheral nervous system (PNS) that controls involuntary body function.
    • One of the stress hormones, noradrenaline (or norepinephrine) actually seems to affect the brain’s processing of pain, causing analgesia (insensitivity to pain), researchers found. For instance, during your panic (in flight) you may not have realized that you have bruised your arm until after the stress is gone. Another is that you may be able to tolerate more pain when during a fight with someone or something (like burns from fire).
    • Activity of the sympathetic division
  3. Exhaustion: This occurs when the body has depleted its resources, either before, during, or after the stressor ends.
    • Exhaustion may lead to the formation of stress-related diseases such as hypertension and a weakened immune system, or even the death of the individual if external aid is unavailable.
    • When the stressor ends, the parasympathetic division (rest-and-digest response) activates and attempts to restore back lost resources. The body still produces stress hormones, however.

Alarm and resistance are stages that we frequently experience throughout life, allowing us to adapt to life’s harsh demands. However, it is the prolonged secretion of the stress hormones during exhaustion that bring the fatal effects of stress. This aspect convinced other researchers to see the connection between stress and, in Selye’s words, diseases of adaptation.

Example: You are out for a jog. Suddenly, you hear the barking of a dog. You later realize that it’s right behind you, and it’s chasing after you.

  • Alarm: Upon seeing the large dog, its fangs, and its foaming mouth, you immediately deduce that you’re in danger. So, you get goosebumps and feel a sudden rush of energy, and try to run (flight) to a safe spot before the dog bites you.
  • Resistance: As you flee, the body releases additional adrenaline so long as the stress (the dog) is present. You can run for an extended amount of time and distance, more than when you’re just out for a brisk sprint. Your body will suppress any pain you may feel in this stage.
  • Exhaustion: The dog is gone. You are very, very tired and starting to lose consciousness. There may even be a chance you will suffer a heart attack. Lingering goosebumps indicate stress hormones are still present.

Stress and Your Defense

Selye first discovered the relationship between stress and the immune system. Psychoneuroimmunology concerns the study of physiological effects (stress, emotions, behavior, thinking, etc) on the immune system.

When stress is good

When leukocytes (white blood cells) surround a pathogen, they surround it and release the chemicals and enzymes into the bloodstream. Such chemicals activate receptor sites on the vagus nerve, alerting the brain that the body is sick and making the immune system work even harder.

Stress works the same way except that rather in the bloodstream, it starts in the brain. Just as constant exposure to weak pathogens further activates the immune system, so does exposure to stress. In other words, stress makes your body’s soldiers even stronger.

When stress is bad

The immune system serves to protect the body from harmful pathogens; however, it may find itself under friendly fire. Basically, when you subject yourself to stress, and you deal with it the wrong way (see first link above), or when you take in too much, you are bringing yourself down. The body produces cortisol, which suppresses inflammation, during stress. If it lingers for too long in the body (chronic stress), we will begin resisting it, leading to chronic inflammation. The body resists by releasing cytokines, substances associated with chronic inflammatory and autoimmune conditions. Such negative effects persist even after the stress itself disappears.

Illnesses brought by stress include heart diseases, cancer, depression, and HIV/AIDS. It affects not only those exposed to stress, but also those around them.


When we are stressed or challenged, we feel we are threatened and need either to fight back or run away. Some forms of stress are good and beneficial whil others are bad, but having too much of stress is tantamount to suicide. We need to change either our environment, where there are less problems, or our reaction thereto, where we can use stress always as a motivator.



Claudette, A. (2011). Introduction to Psychology, 1st ed. Pearson Education South Asia Pte Ltd.

Selye, H. (1956). The Stress of Life.

Autonomic Nervous System. Retrieved from


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Dealing with Stress: The What and the How

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  1. Great article in regards to stress and how our body deals with it. I really liked how you put it in 2 parts, one where stress is good for the body and the other where stress is bad for the body. I also learned something new too; the general adaptation syndrome and the different stages of them. It definitely reminded me of our flight or fight response that many people associate with stress. I can definitely relate to the general adaptation syndrome’s stages, especially towards the resistance stage since sometimes I get random bruises that pop up from nowhere and now I know why! Plus, great example on the general adaptation syndrome; that definitely makes the readers really connect to it. Towards the end, on your conclusion, minor typo but that’s alright. But, in regards to how stress can lead to suicide, maybe you can also touch base on the cultural aspects of how countries treat stress differently? Also, maybe you can elaborate on how stress can lead to HIV/AIDS? After reading that part, I wanted to know more about that. In regards to the two points of when stress is good and bad for you, it would be cool if you could also put in real life examples of that so that your readers also get a better idea and connect with it more. Overall, great article!

  2. Stress is a complex issue and you formatted your article well to explain it like using good examples. I also liked how you pointed that certain type of stress is either good or bad. I feel like you can definitely expand your conclusion or perhaps talked more about how we can change our environment. But, I think you should elaborate more on your conclusion. Overall, this is a great formatted articles filled with good examples

  3. We are currently in some of the most stressful times the world has ever seen. Metaphorically, it makes sense that people these days are so desensitized to pain. We are in a continuous fight or flight situation pretty much 24/7. I think as a planet we have seen enough. Even though this isn’t what the article was about it lead me to think about stress on a broader scale. This article was very informative. How does stress lead to HIV/Aids? That’s super interesting and I would like to know more about it.

  4. Really well detailed article, I think your use of diction was spot on and some of the information was quite news to me, like stress being able to give HIV/AIDS. Most of us could agree that stress will for ever show its face in each and everyone of our lives but I also feel knowing the causes and medical intake on the study of stress and what it really is and how it really affects the body/ brain can benefit readers greatly such as myself. I even remember covering the three stages of Stress that you mentioned in my Intro to Psych class. All in all this article is great. Thanks!

  5. I remember first learning about how constant stress can have devastating consequences to one’s health. I find it fascinating that the stress response was designed as a protective measure, but is now detrimental to survival in modern situations. Currently, humans as a species typically don’t have to worry about getting eaten by a predator or dying from exposure (though these things do happen occasionally); but instead have to worry about things that would not matter to our predecessors. Personally, I find myself stressing about money, working a boring job, and planning a wedding; and knowing that stress is harmful paradoxically causes me to stress even more. However, with these new stressors come new coping techniques. Fidget spinners and other devices have become very popular, and I think some of that popularity has to do these devices providing anxious individuals an outlet for the energy that builds up when they are in stressful situations. Where once we had auditory and visual stimuli to keep our minds off of stressful issues (music and movies), we now have kinesthetic stimuli to give our antsy extremities something to focus on.

  6. Oh boy, I sure can relate to this topic. I may not have faced a lion on the savannah, but I remember stressing about the gauntlets of tests, papers, and presentations in high school as if my life depended on it. The mental and physical burnout took me years to recover from.

    I didn’t know that Hans Selye was the person to pioneer this field of study. Have there been any more recent studies on the health effects of stress?

    In regards to your references, what page numbers did you reference in the article? Consider looking up citation styles such as APA or MLA and choosing one for your references.

    I’ve heard before that stress leads to chronic inflammation and a weakened immune system, but the wording in the second half of the article is confusing to me.

    And to give feedback on further topics of exploration, what populations are susceptible to chronic stress and the negative effects? Have there been studies on people who have lived in war zones or those who’ve grown up in abusive environments? What do studies of meditation and mindfulness say about stress reduction?

  7. Stress is no stranger to anyone living in this current era with all the stressors that are upon people in a day to day fight to overpower it. I wasn’t aware of the general adaptation syndrome and found it to be quite interesting in relation to how it progresses in three stages. Though, when I reviewed the facts on alarm, resistance and exhaustion it really made me think of my own personal experiences I’ve had with stress. When I was attending college, I remember how certain deadlines would push me to sleepless nights with rushing between work and school. It had my stress level go off the charts. I would experience alarm with increased heart rate to get it done before the deadline was up. I would build resistance to not sleeping due to the alarm reaction of not having a project done in time. In result, I would pull all-nighters for several days in a row. The initial worry of having it done it time kept a resistance to overworking my body and building my anxiety. Until the initial fall out of exhaustion where my body would just fall asleep involuntarily. This would then repeat itself when I would force myself awake again to keep going because of the stress of ideas of failing and wasting money. I am glad to learn that there are at least good forms of stress that can help make the immune system work harder and become stronger. At least there is some form of buildup but initially finding ways to deal with stress can help prevent bringing yourself down and becoming sick. I really enjoyed this article with the included facts and details on how stress can work from the inside to affect us physically.

  8. This gives a very procedural and structured explanation of the physiological account behind stress as proposed by Hans Selye. It is indeed interesting to break down and understand the biological processes in our body upon encountering a stressful event, as well as understand when the process starts to reflect ‘bad stress’ (distress) instead of ‘good stress’ (eustress). Thank you for the informative write-up!

    However, the article mainly focuses on the short-term immediate physiological response of stress, and I thought it would be interesting to delve into more long-term effects arising from chronic stressors, which is what many of us may encounter in our daily lives. For example, bullying in school/workplace, marital problems or more closely experienced in the current world, refuge and death issues that arise from war. Highlighting the gravity of prolonged stress by pointing out its adverse physical and mental health impacts can help to raise awareness amongst our society so that we may be better equipped with the understanding to aid the people encountering such chronic stressors.

    There are two distinct stress systems that have been proposed to exist in our bodies, the sympathetic-adrenomedullary system, and the hypothalamic-pituitary-adrenocortical (HPA) system. The content of the above article focuses on the sympathetic-adrenomedullary system, which demonstrates the acute “fight or flight” response, where the sympathetic system is activated during crisis. On the other hand, the HPA system represents how our bodies mediate a stressful factor in the environment, and is thus more characterized by its neuroendocrine response to prolonged and long-term stress. It operates by the following process:

    1. Hypothalamus and pituitary gland communicates through action potentials or the release of hormones which flow through the blood network
    2. The pituitary gland then releases hormones to communicate with the adrenal glands (located next to the kidney)
    3. The adrenal cortex then releases cortisol

    Cortisol is an important stress-related hormone that induces important effects on our body and brain. For example, Singer and Zumoff (1992) demonstrated that cortisol may suppress gonadal function when they found that the blood level of testosterone in male hospital residents (doctors, not patients) was severely depressed, presumably because of the stressful work schedule they were obliged to follow. It was also found that cortisol can directly impact hippocampal functions such as one’s memory. Humans who showed increasing 24-hour cortisol for 3 to 6 years progressing to the point of high levels were found to have more memory impairments and smaller hippocampal volumes (Lupien et al. 1998). These studies all highlight that prolonged stress from work and school can have profound effects on our lives.

    On another note, I am referred to a link to another article in the first paragraph of this write-up. The article talked about cognition as a mediating factor to stress-processing, which comprises of how an individual primarily and secondarily appraises the stress event. Secondary appraisal involves the estimation of resources available to cope with the stress. Upon reading, I recalled Cohen and Wills (1985)’s work on social support as a factor to developing depression upon encountering stressful events. I thought that social support could thus be seen as a ‘resource’ to cope with stressful events, which may then determine if an individual develops depression after a stressful event. Cohen and Wills (1985) thought of social support as operating in two ways through a main effect or, through a buffer.

    The main effect hypothesis states that people with high levels of social support are less likely to be depressed regardless of what happens to them. This is because individuals who experience close bonds, acceptance and caring from appropriate social support will feel greater self-esteem and a sense of self-efficacy, helping to guard against depression. Meanwhile, the buffering hypothesis suggests an interaction of social support with life stress, whereby the presence of social support during a life stress event acts as a buffer to these stressors. It seems that both conceptualisations of social support are correct in some respects, but each represents a different process through which social support may affect well-being upon encountering stress.

  9. Reading this was like being right back in EMT School. Eustress (good stress) and Distress (bad Stress) was a major topic in our class, because it effects patients, as well as the EMT themselves. Being in Emergent Medicine means constant ups and downs, long periods of quiet (thankfully) punctuated with instant “Get Up and GO!” moments, that can then last for hours, depending on the situation or injuries. Eustress enhances our immune system and makes us stronger in both physicality, and emotionally. Think of the benefits of working out, or doing house work. It gets us moving, and we can feel its benefits almost immediately! While Distress, is generally overwhelming and overtime, destructive.

    It’s crucial to be aware of how to perform self care when in moments of Distress. When it is appropriate to do so of course. But this means, taking a nap on your day off, or going out and picking up ingredients to your favorite meal, cooking it and enjoying it. To catching a movie with friends or a nice long cuddle with your Cat! Eustress can become Distress if it is prolonged and goes unaddressed. Self care and Self Awareness is crucial in keeping oneself out of Distress, and within the acceptable boundaries of Eustress.

    Really good topic for an article! I would have liked a more, personal interpretation in the Authors conclusion, maybe a quick anecdote or personal experience to highlight the important points being made in the article. Overall, an enjoyable read.

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