Most of us have our own idea of what stress feels like: headaches, dry mouth, neck pain, stomach cramps, sleepless nights… But what actually happens in the body when we have sudden or chronic stress?
Stress is often called the flight or fight response and it’s part of the biological mechanism we use to cope with threatening situations. When it happens, heart rate rises, breathing becomes faster, blood pressure increases and our muscles tense up.
Stress is a natural and healthy response to a threatening outside stimulus. But in modern life, our stress response often becomes frequent, habitual and even continuous, a chronic, near-constant state that has profound, potentially damaging effects on our health and well being.
In modern society, we don’t often face physical threats, but there are many regular, less dramatic triggers – pressure at work, arguments at home or on social media, cost-of-living pressures and unpaid bills, the pandemic, the drumbeat of war… In our highly complex, technology-dependent world, there are also many less obvious background stressors which create constant pressure.
And we all experience traumatic life events like the loss of a loved one, job loss and relationship break-ups. Over the years, we’ve seen countless examples of how one or two of these events combine with other factors like childhood trauma and lifestyle choices, to become the triggers for serious health challenges.
Understanding all of this is on a physiological and psychological level is made more complicated by the fact that we’re all different – each person’s stress response depends on personality type, genetic makeup, past experiences, the level of social support we have and a whole host of other factors (1).
The Role of Cortisol and Adrenaline in the Stress Response
In getting us ready to run or fight, our stress response involves the release of two key hormones:
- Adrenaline. This gets our heart pumping, the blood flowing and helps get fuel to areas like the muscles.
- Cortisol (often called the primary stress hormone). This helps release glucose into the bloodstream and makes sure that the brain has enough supply to cope with the stressful event. Cortisol also plays a role in releasing other substances that are involved in the repair of tissues in the event we are injured.
In a normal stress event, this is a natural process designed to protect us. With chronic stress, however, cortisol is released often or nearly all the time. That can have serious health implications in the long term. It means increasing blood sugar levels that can lead to insulin resistance and type 2 diabetes (2), the suppression of the immune system and high blood pressure that can contribute to heart disease and strokes.
The problem is that glucocorticoid receptors are present in every organ and system in the body, which can mean wide-ranging and damaging effects if the stress response is not controlled.
Autonomic Nervous System and Stress
Even the occasional brush with danger is just part of the constantly shifting state of the Autonomic Nervous System. The ANS is the part of our central nervous system that keeps all vital processes and systems working automatically and unconsciously.
When it’s mainly in fight-or-flight mode, it’s called the Sympathetic Nervous System; when we’re chilled-out and contemplative, it’s the Parasympathetic Nervous System.
Many of the organs and functions that are affected by stress are controlled by the ANS. This helps the body react without us having to consciously do something. Signals sent to the brain are transformed into involuntary responses such as raising blood pressure, dilating blood vessels in the lungs and providing bursts of energy.
The stress response involves the HPA axis (3) which involves the hypothalamus in the brain sending messages to the pituitary and adrenal glands which help release the stress hormones. If this axis is continuously active and we are unable to switch it off, organs and body systems are constantly over-activated and our health can begin to suffer in many different ways.
Stress at a Cellular Level
Even at the level of individual cells, research is beginning to show that chronic stress has a significant impact. Some studies have connected it with a shortening of chromosome elements called telomeres, a central factor in the ageing process, and have been linked to development of type 2 diabetes, heart disease and other conditions (4).
Other studies show that chronic stress can change the morphology of nerve cells, causing dendrites (the parts of the cell that branch out to form connections with other cells) to retract. It can cause an imbalance of white and grey matter in the brain which affects mental health. This may account for why people suffering from chronic stress tend to develop other conditions such as anxiety disorders and depression.
Stress and the Immune System
Perhaps the most profound danger from chronic stress lies with the immune system. Excessive release of cortisol suppresses our ability to fight infections and leads to chronic inflammation.
Inflammation is generally considered to be one of the leading factors in chronic illnesses such as heart disease, diabetes and cancer.
Stress, Anxiety and the Gut
Some of the most advanced and exciting medical research is proving the essential role of our gut flora, or microbiome, in maintaining physical and mental health.
Unfortunately, stress can directly affect our gut health. It can slow digestion so that vital nutrients don’t get to the internal organs and it may harm the good types of gut bacteria. Again, there’s a knock-on effect in the form of more inflammation (most of which begins in the gut) as a precursor for chronic conditions such as heart disease and cancer.
Stress and Sleep
If you’ve ever been extremely anxious, with the same thoughts going round and round in your head — then you know what it’s like to miss a lot of sleep. When we fall into a deep sleep, a wide range of healing processes begin, essentially working to repair the body during rest.
This includes the release of human growth hormone which helps increase energy levels during the day, reduces body fat and even increases bone density and muscle mass.
Lack of sleep not only makes us tired and in need of a quick energy fix. It also sends our appetite hormones haywire. The result is often overeating, drinking too much alcohol or energy drinks, and a cycle of weight gain and fatigue.
Reducing Stress to Improve Health and Wellbeing
With all the complex effects that chronic stress and anxiety have on the body, many people are now focused on reducing it. Non-invasive approaches such as yoga, meditation and other relaxation techniques have seen huge mainstream growth, especially during the pandemic.
Despite the fact that one of the single most effective methods of stress management is still meditation techniques developed thousands of years ago, modern technology offers some of the most exciting potential. There are many approaches but one of the most promising is Pulsed Electromagnetic Field or PEMF therapy (using low-frequency, low-intensity magnetic pulses). Others involve sound (binaural beats, certain types of music and sound to body vibrations), electrical stimuli, bio-feedback and laser or LED devices.
Combined with meditation and cognitive therapies, technology now offers some of the most profound improvements in our stress responses and psychological states. In today’s world, the stakes are getting ever higher.
- Mohd. Razali Salleh Life Event, Stress and Illness The Malaysian Journal of Medical Sciences, 2008
- Robert A Rizza et al Cortisol-Induced Insulin Resistance in Man: Impaired Suppression of Glucose Production and Stimulation of Glucose Utilization due to a Postreceptor Defect of Insulin Action The Journal of Clinical Endocrinology and Metabolism, 1982
- Staying Healthy: Understanding the stress response Harvard Health Publishing, 2020
- Stacy Lu How chronic stress is harming our DNA American Psychological Association, 2014