First of all, let’s notice the role of perception in the biology of stress. This is what triggers the stress response. When we experience stress or something unpleasant, it sets off a physiological cascade that affects our brain and body. The perception of the stressor, or threat, alerts the HPA axis (which is composed of the hypothalamus, pituitary and adrenal glands) to react to the threat with the well-known weapons of fight, flight or freeze.

Subsequently and very quickly, the adrenals release cortisol and other hormones into the bloodstream and help to coordinate reactions from other bodily systems, like the cardiovascular, immune, digestive, and reproductive systems to name a few.

When the stress has subsided, reuptake of the chemical messengers, like cortisol, is done via particular receptors in the brain.

The stress system is calibrated to deal with intermittent stress after which it is designed to return to a balanced state. However, much of our stress seems to hang around and doesn’t subside quickly enough. Thus, chronic unremitting stress affects the system’s ability to regulate itself, and affects the efficient reuptake of stress hormones, which keep circulating in the body. The wear and tear of a chronically activated stress system degrades the functioning of the immune system and can lead to disease.