On the other hand, the parasympathetic nervous system regulates the “rest and digest” functions. In other words, this system controls basic bodily functions that happen while one is sitting quietly reading a book (1).

Chronic stress or prolonged activation of the stress response can change the balance of the stress response system. Cortisol, also known as the stress hormone, is released by adrenal glands, located on top of both kidneys, in response to any stress we face. The cortisol rises and declines as we pass the stage of stress but being in a longer and consistent stage of stress, may eventually contribute to an imbalance in the daily rhythms of cortisol production.

Adrenal glands get affected by prolonged stress which dysregulates the hormone production network which includes Hypothalamus, pituitary and adrenal glands (HPAaxis). Genetic background, early-life environment, and current life stress are the main factors that determine the HPA axis activity that controls the amount of cortisol a person is exposed to during adulthood.