Stone Age men had the luxury of long rest periods between such bursts of intense physical activity during which they could recover their composure. In our hectic contemporary world, rest periods have become so short that some of us remain in a debilitating, constantly over-stimulated state. The human stress reflex varies greatly from person to person, probably based on genetically determined set points. Some of us have a hair-trigger reaction to even the mildest stimuli, while others remain nearly inert until their very survival is threatened. Whenever hyperstimulation of the circulation becomes marked or prolonged, it predictably punishes the body's organs.
Cardiac damage can occur in as short as a few weeks of continuous circulatory over-stimulation.
There's an intriguing theory that suggests that each of us is programmed with a finite number of heart beats during our lifetime, and that speeding up the heart inevitably brings us to an earlier death. One of the challenges of modern living is to gain awareness of our own stress reflex, when it starts and when it reaches a level where we must control it to avoid hurting ourselves. Because we are thinking beings, we typically develop mental correlates of the physiologic changes brought on by the stress reflex. Rarely the stress reflex will call up seemingly unrelated feelings like guilt or paranoia. The most dangerous emotion associated with the stress reflex is internalized anger.