The more I read about human disease (in particular diseases linked with chronic inflammation like diabetes, obesity, metabolic syndrome and even depression and anxiety), the more I blame stress for the surge in numbers of chronic diseases seen today. The overwhelming majority of the studies examining the stress response over time show very clearly that individuals who live in a chronically stressed state consistently have worse health outcomes. However, while it is certainly beneficial to reduce and avoid chronic exposure to stress, there are some short-term benefits of acute stress that can serve to increase performance, focus and even motivation. In today’s post, I want to try and simplify this topic by introducing the stress response from an evolutionary perspective and discussing some of the short-term benefits before moving on to the negative outcomes brought on by chronic stress.
**As usual, note that entire textbooks and research collections are designated to this topic. I have only chosen to cover some of these topics broadly for your benefit.
The Stress Response from an Evolutionary Perspective
I hear people everyday complaining of stress. In a world where it always seems like there’s something that “needs” to be done, rarely do we find a time to relax and repair. But what is stress from a physiological perspective? Why does it make us feel anxious, tired, and overworked? Stress is actually a protective response for humans in which hormones such as cortisol and epinephrine are produced to provide us with the ability to adapt to certain conditions. You can think of this as a coping mechanism for the body in times of danger to increase arousal through activation of what’s called the sympathetic branch of the nervous system. Sympathetic activation leads to increases in bodily functions such as endogenous glucose production, blood pressure through vasodilation, heart rate elevation, arousal, and increased respiration. This makes sense because in the past, if we wanted to flee from danger such as attack from prey, we needed to develop the ability to allocate as many resources as possible (glucose, oxygen, attention span) to the task at hand. Then, once the attack was over, our bodies could return to the resting stage, also know as parasympathetic activation.
To briefly summarize, stress is an adaptive response that primes the body for attack. In short-bouts, our bodies handle stress quite well. However, long-term exposure to stress is a different story, as a heightened activation of these systems is very expensive for the body and it eventually begins to wear down. I’m sure all of you reading this have felt tired and worn down after a stressful day. Well, if your heartrate is elevated, blood pressure high, and liver is working overtime to increase blood glucose, your body (through the feeling of fatigue) is most likely sending you a message with instructions to rest, relax, and repair. In my opinion, it’s not about avoiding stress completely, that’s impossible and unnecessary. I believe it is more important strike a balance with stress that allows you to both perform at a high level (acute stress) and avoid getting worn down (chronic stress).
When Stress Helps Us
As I mentioned above, I don’t believe all stress in bad. In fact, in my own life, the stress response has probably helped me perform in a variety of situations. A perfect example of this would be in preparing for a hockey game. Prior to big games, I could literally feel my heart rate elevate and would often sweat at a ramped pace. This makes sense- my body was preparing for battle. However, would it be good for me to live my life in this state? Probably not. Anyway, here’s a few additional benefits of short-term stress exposure:
**Before reading the examples, look at this graph. Notice that there is an optimal amount of stress that leads to peak performance. Beyond this optimum level of arousal, the body begins to fatigue and the negative effects of stress set in.
It aids us in preparing and performing in events that require performance such as athletic events, workouts, presentations, and exams.
Short-term stress helps us build up resilience, allowing us to cope and handle future stressors.
In times of danger, the short-term stress response provides us with the resources such as oxygen and glucose to respond. It does this through shutting down bodily functions such as digestion, ovulation, and immunity.
So, in summary. In times of danger or times requiring peak performance, the stress response (adrenaline and cortisol) is beneficial. Now let’s look at what happens with chronic stress.
Chronic Stress- A Major Threat to Human Health and Longevity
One of the most interesting aspects of the stress response is how dramatic the differences are between short-term and long-term exposure. What in the acute phase can provide us with energy, focus, and strength can lead to fatigue, weakness, and disease if it persists in the long-term. But why? This is where we must look at the systems in play, in particular what happens with glucose homeostasis, the immune system, and the body tissues:
1) Glucose Homeostasis- During the stress response, both adrenaline and cortisol are released into the bloodstream. Cortisol is a glucocorticoid hormone that is catabolic in nature. Catabolism means to break down, so cortisol acts to breakdown stored carbohydrates (glycogen) and proteins to glucose. This glucose then enters the bloodstream to be used for energy production.
Why long-term cortisol surges are bad: Long-term cortisol elevations will lead to long-term elevations in blood sugar levels. To counteract this, the pancreas secretes insulin to remove the sugar from the blood. However, if blood sugar is constantly high, insulin remains elevated. Elevated insulin levels are a major driver of fat storage and obesity. Further, cortisol signals the body to store fat rather than burn it, further contributing to weight gain (in particular around the abdominal region).
2) Immune Function- Cortisol halts the division of immune cells such as lymphocytes. Think of it this way- your body isn't concerned with bacteria or viruses when a tiger is chasing you. However, chronic immune suppression is dangerous, as it opens up the opportunity for all sorts of infections to occur (including bacteria and viruses). This is why we often get sick after long, stressful weeks! See more here- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1361287/?utm_source=Global+Healing+Center&utm_campaign=87899af75f-Natural_Health_Blog_RSS_Feed&utm_medium=email&utm_term=0_7950820145-87899af75f-107880133&_escaped_fragment_=po=29.3860
3) Tissue Breakdown- Cortisol elevation leads to decreased protein synthesis. This leads to less opportunity for repair of muscles, bones, and connective tissues. For active individuals, this can predispose you to injury as the body isn't given the optimal environment for repair.
I hope I have made it clear that you should take measures to control the stress response. However, I realize this is easier said than done, so I have come up with a broad list of actions that you can take to counteract the more stressful times in your lives.
Counteracting Stress- Striking a Healthy Balance
As I mentioned above, you will not avoid stress completely in the modern world. However, you can take some steps to limit the stress and avoid the negative health consequences associated with chronic elevations:
Eat a diet rich in vitamins, minerals, and antioxidants: Avoiding nutrient depleted food sources such as packaged and refined goods will only exacerbate the stress response. By providing your body with whole, nutrient dense foods, you can ensure that you’re providing the raw materials for a healthy stress response, while limiting inflammation.
Exercise: This is obvious to me, but exercise in any form is beneficial. Endorphin release, insulin-independent glucose uptake, and much more. Stay moving!
Meditate: It’s hard, I know. However, just 5-minutes a day can provide some serious benefit. If you really can’t do it, try yoga.
Don’t let your brain talk you out of relaxing: too often we tell ourselves we aren't good enough, don’t work hard enough, and don’t have the things we want in life. This leads to increased feelings of stress and anxiety to be constantly doing something. Trust me- all of the stress is counterproductive. Give yourself some credit, take a few breaths, and learn to relax throughout your day.
I know this post is a bit longer than most, but I feel that is warranted given the importance of this issue. Stress-management is key to living a happy, healthy, and productive life and I hope this post helps you in adopting a lifestyle that allows you to do so.