Why are less stress-hormones in the body important?

The stress-system is - from the evolutionary point of view - a very old survival-system. When it evolved, survival situations - e.g. running away from a wild animal - needed may be 30 minutes. Either the predator or the hunted animal succeeded. The stressing situation came to an end and the stress hormone-production of the body stopped.

When, for example, some caregivers may be physically or emotionally abusive and if this is the case, it is  not safe for the body or psyche of the child and the stress goes on for years. Or at work having deadlines all the time. The corridor of well-being gets tight. The body cannot relax any more and stress-hormones are produced continuously. 

Counselling gives insights, kinesiology works with the autonomous reactions of the body.

What are the impacts when the body is covered with a high level of stress hormones over a long period?