Stress has a surprisingly broad action on our whole being including our immune system and our thinking capacity.
When I use the word stress, I am using it as a general term to describe any potential threat to our well being. So we are talking of everyday emotional states like fear, anxiety, worry, tension etc.
A basic understanding of our biological response to stressful situations will put a lot of what I am going to say in context. It did turn on a few light bulbs for me when I first read this up in Bruce Lipton's excellent Biology of belief.
Our biological stress responses involves a series of signalling/hormonal mechanisms that result in the production of the stress hormones cortisol and adrenaline. These hormones prepare the body by diverting all of the bodies energy resources for a fight/flight response:
The above responses make a lot of sense in the face of an acute threat like being chased by dog or a tiger. You want all your energy to be focused on dealing with the external threat rather than on internal processes like digestion or fighting an infection.
Similarly fast reflexive decisions are favored over slow analytical thinking as they provide higher chance of survival. You really don't want to appreciate the flowers or take a lot of time to decide if you should run left or right when you are being chased :).
What I have discussed above has surprising implications in everyday life.
The stress response is not an objective response. It is triggered when you perceive a situation as a threat. In other words, the triggers to stress are a matter of individual perception.
In modern life, most individual stressors are not physical in nature and our biological responses which are designed for short lived physical stressors have a very limiting effect on our experience.
Consider the following scenarios that a fair number of people find stressful:
As the examples and discussion makes it clear, even temporary situational stress makes us dumb by impairing our cognitive abilities. This has practical performance repercussions in everyday scenarios.
Chronic stress on the other hand has important health implications. Diverting energy and nourishment away from our visceral organs and depressing our immune system exposes us to illness and reduces the body's ability to heal itself.
No health intervention like a diet or exercise or medicine can be effective in the face of depressed immune and internal systems. Any effort to restore health must take a serious look at the the stress situations of the person involved.
Ability to manage our stress effectively can dramatically affect the quality of our everyday experience.
Given that most modern day stressors are subjective, ability to manage and alter our perception is a key skill in managing stress.