Rule #8 of John Medina's Brain Rules: Stressed brains don't learn the same way.
Emotional stress causes us to lack focus and inhibits our ability to retain information. This impacts kids' school work and employee's productivity.
The body's defense system releases adrenaline and cortisol in immediate response to a serious but passing danger, such as a oncoming car in your lane. If you are facing hostility at home or work on a regular basis or YOU are the one with raging anger daily - your body deregulates a system which was created to deal with short-term responses. This becomes dangerous to your health.
Chronic stress produces adrenaline which creates scars in your blood vessels that can cause a heart attack or stroke, and cortisol damages the cells of the hippo-campus, crippling your ability to learn and remember information that may be crucial to your success.