Your body is hard-wired to react to stress in ways that are meant to protect you against a life-or-death situation. A couple million years ago this was absolutely necessary. Our ancestors primarily dealt with immediate threats, like a lion looking to you as their next meal.
When the danger passed, we were safe to return to baseline and go about our business. In our modern world, we rarely find ourselves up against predators but that does not mean that we do not face dangers, they are just subtle and constant- numerous demands that accumulate each day (Check out some common stressors here). Unfortunately, our body still recognizes and treats each one of these events as an attack on our life.
How Stress Works
Stress begins in the brain. The amygdala, our “emotional center”, detects and assesses potential threats and if need be, alerts the hypothalamic-pituitary-adrenal Axis (HPA-axis) to trigger a stress response. A signal is sent to the hypothalamus to release corticotrophin-release hormone (CRH), which binds at the level of the pituitary, signaling it to release adrenal corticotrophin hormone (ACTH) into the bloodstream. ACTH travels to the adrenal glands where it prompts the release of multiple stress messengers including adrenaline and cortisol.
The release of cortisol, our primary stress hormone, causes a number of changes that helps to protect us in the face of a threat. For example, it mobilizes energy (in the form of glucose) and increases your heart rate, blood pressure, respiration, muscle tension and the availability of substances that repair tissue. It also temporarily alters the immune system and suppresses our digestive and reproductive systems as these functions are not necessary for immediate survival (i.e. running from a tiger).
High levels of cortisol in the blood are sensed by receptors in areas of the like the hypothalamus and hippocampus (our memory center), signaling the hypothalamus to cease the production of ACTH and shut off of the stress response. This process is referred to as a negative feedback mechanism and it is our bodies built-in protection against constantly being in “fight-or-flight”.
The Effects of Stress
In the short term, the changes we experience in response to stress are adaptive for survival. Acute surges in cortisol calm inflammation, enhance memory, focus and decision making, and efficiently revs up metabolism to replenishes our energy reserves. However, if we experience repeated stress over many weeks we can alter our sensitivity to stress. Stress can be physical or emotional.
Frequent stress impairs the ability of the hypothalamus to turn off our stress response, resulting in an accumulation of stress hormones that wear and tear on the brain and body. While our bodies are extremely adaptable and can continue to function under very high levels of stress for a prolonged period of time, we start to do so at the expense of our other regulatory functions.
Our immune system, digestive system and reproductive system become chronically downregulated and may shut down completely. Unfortunately, this is usually a subtle, slow build and we often don’t notice that something is wrong until we are experiencing a number of uncomfortable symptoms, many of which you probably don’t readily associate with stress.
Written By: Coach Courtney