Understanding the stress response Let’s start with the basics: the sympathetic and parasympathetic nervous systems. Both are part of the autonomic nervous system, a regulatory center that influences organs, vessels, glands, genitals, and digestive system, driving the survival reactive and regulatory involuntary functions of the body.
The parasympathetic system manages metabolism, reproductive health, sleep and energy cycles, body temperature, and fluid regulation and is often referred to as the “rest and digest” state while the sympathetic nervous system is the reactive survival response is often referred to as “fight or flight.”
When the body is under stress, it favors the sympathetic nervous system. This drives the activity of the hypothalamic-pituitary-adrenal axis (HPA axis), stimulating the adrenal glands to release cortisol and stress-responding neurotransmitters.
Hormones serve as regulatory substances, providing stimulation or repression of signals based on receptor function and balance in the body. Our metabolism, sleep, sexual hormone function, and mood are all influenced by the hormone regulation of our autonomic nervous system and balance of our HPA-axis. Chronic stress can disrupt hormone regulation and cause major metabolic consequences.
Thyroid hormone regulation Let’s start with the thyroid. When the body is at rest, the hypothalamus releases thyroid-releasing hormone (TRH). In response, the pituitary gland releases thyroid-stimulating hormone (TSH), increasing thyroid hormone production and regulation.
But, in times of stress, the adrenals are prioritized over thyroid regulation, and energy is shunted to them. What’s more, cortisol, which is released in response to stress, can interfere with how the inactive thyroid hormone, T4, is converted to the active form, T3. In addition, stress can interfere with T3 expression, all of which puts the brakes on metabolism.
https://www.mindbodygreen.com/articles/how-stress-messes-with-your-hormones
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