The Science Behind Stress


Conversations around stress are everywhere. We know that chronic stress is rampant in our society and that it’s a major contributor to our overall abhorrent state of health, but WHAT really is stress?

This week I’ll explain the effects of stress on our bodies.

Our bodies work to maintain homeostasis. We all remember this concept introduced to us in high school, right? Homeostasis is the body’s ability to maintain a certain pH level, an ideal level of oxygen, a certain temperature, etc. A ‘stressor’ is anything that throws our body out of homeostasis, and the ‘stress-response’ is how the body reestablishes homeostasis.

The stress-response plays a major role in our survival today. Drought, famine, parasites and other unpleasant experiences, have been survived because our body is reasonably good at handling sustained disasters.

Unique to humans is the ability to activate the stress response via psychological and social disruptions. We actually generate all sorts of stressful events purely in our heads: finances, relationships, traffic, etc. Viewed from the perspective of evolution, chronic and sustained psychological stress is a recent invention and mostly linked to humans. Further, regardless of the actual stressor – injury, starving, too hot, too cold, mortgage, relationship woes – you turn on the same hormonal milieu responsible for the stress-response.

Enter the nervous system, which is broken down into two parts: the sympathetic and parasympathetic. The nervous system is a network of fibers that are a continuum of the brain and spinal cord and branch out to innervate muscles and organs. One half of the nervous system is activated during stress (the sympathetic) and another half is suppressed (the parasympathetic).

During stress, like when someone jumps out from behind the door, the sympathetic nerve fibers release adrenaline. Adrenaline is responsible for making your stomach clench and your hair rise. The parasympathetic on the other hand is activated during sleep and relaxation and promotes growth, energy storage and digestion. Have a huge meal, sit there, happily full and drowsy and the parasympathetic nervous system is activated. Run for your life across a field and you’ve turned down the parasympathetic and turned up the sympathetic. Thus, the autonomic nervous system works in opposition. When our sympathetic nervous system is activated, blood is diverted to the muscles; when the parasympathetic is activated blood flows to the center.

The brain is the master gland and can activate the hormonal stress cascade through experiencing or thinking about a stressful situation. Stress triggers the brain to release hormones that travel to the adrenal gland where more hormones, namely glucocorticoids, are released. Glucocorticoids are steroid hormones and act similarly to adrenaline (released by the sympathetic nerve fibers); together they make up the workhorses of the stress response. Stress stimulates the pancreas to release glucagon and together with adrenaline and glucocorticoids, increased levels of sugar in the blood. Stress activates hormones that inhibit reproduction (prolactin), hormones that affect the heart (antidiuretic hormone), and hormones that prevent growth (growth hormone).  

These days, our lives are inundated with stressors: student loans, divorce, illness, work, etc.  Our bodies do not differentiate one stress from the next and the same physiologic cascade ensues. Our bodies are not designed to withstand the constant exposure to stress hormones and this contributes to the foundation of disease and imbalance.

Stay tuned next week when I discuss WHAT you can do to help your body adapt to these modern conditions.

If you want to learn more, I’ll be speaking at the Portland Spring Wellness Pop-Event! Click here to get your tickets and learn more!