Stress has various effects on the brain, including triggering a physiological response in the body.  It is why managing stress is important.  Chronic stress can come from chronic illness, which is why stress must be kept under control if you want to have a peaceful, normal life.  Stress causes the amygdala part of the brain to send a signal to the hypothalamus.  Stress then results in an increased heart rate, charged senses that read the environment for harmful anything, and a deeper intake of oxygen not limited to a rush of adrenaline that helps guide the release of cortisol, a stress hormone that helps restore lost energy.  High levels of cortisol can wear one out, while stress kills brain cells, and can actually reduce the size of the brain, specifically the pre-frontal cortex.  Stress causes massive high blood pressure, heart disease, and diabetes.

                        Works Cited

https://www.tuw.edu/health/how-stress-affects-the-brain/