By Cort Johnson in Health Rising.
“Stress” is an unfortunate term. Usually we think of stress as emotional; in biology, though, stress means anythreat that disrupts the balance (or homeostasis) of the body. The stress response or HPA axis, prepares the body to respond to the threat. Any threat then, whether infectious, emotional, physical, chemical, etc, will initiate the stress response.
Once triggered, the stress response suppresses non-critical functions such as growth and metabolism (i.e., hypothyroidism, long linked to ME/CFS) and reproduction (i.e., hypogonadism, also connected with ME/CFS). It also releases cortisol to make sure the brain, heart and muscles have sufficient glucose (at the expense of less critical functions like digestion). Cortisol also primes the immune system for action (and has a delayed proinflammatory effect).
As noted in Part 1, studies indicate that chronic stress causes a progression from high to low cortisol and can result in the development of cortisol sensitivity – a situation in which the body becomes more responsive to cortisol. (When cortisol sensitivity occurs low cortisol can have the same or greater effects than high cortisol does in healthy individuals.) This increased cortisol sensitivity cannot be measured by cortisol/synacthen tests (which measure level not effect) but it does results from epigenetic changes that can be shown.
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