Stress may be the one thing that we all have in common. We have stress. We are stressed. We feel stressed. We stress.
But what is stress? For clarity we will define stress as the response of mind and body to a stressor or stressful experience.
Stress is a physical expression of our fight-or-flight survival mechanism. A threatening situation will trigger a stress response, which prepares us to confront or flee a possible danger. This helps for immediate danger but unfortunately the stress response is also triggered by tense situations where physical action is not an option, such as an interaction with an unreasonable boss, heavy traffic, or financial problems. In fact, any perceived threat to our goals, our sense of self or feelings of control can set off a stress response.
Stress causes chemical changes in the body that, left unchecked, can have negative effects on both mental and physical health.
Acute stress is a short-term response that originates in a part of our brain called the limbic system, specifically in the amygdala. The amygdala activates another part of the brain, the hypothalamus, which wakes up the sympathetic branch of the autonomic nervous system (our fight-or-flight response system). This interacts with vital organ systems, our skeletal muscles and the endocrine system of glands that secretes hormones.
In all, over seventeen different hormones are released during an acute stress response. Adrenaline and noradrenaline are familiar names. These hormones are released by the adrenal medulla (part of the adrenal glands, two small glands located on top of each kidney).
How long acute stress lasts may vary - the response can last for a few minutes or a few weeks.
The parasympathetic nervous system, mediated by the vagal nerve, counterbalances the acute stress response. It will slow things down again, given time and space. Our centre of reason, the pre-frontal cortex, is also able to step in and influence this pattern, but it often shuts down, leaving us unable to make emotionally intelligent decisions when we most need to do so.
Chronic stress occurs when repeated acute stress responses keep the body continuously alert, negatively affecting health. The parasympathetic nervous system does not get a chance to do its job and calm things down. The ongoing stress response causes the hypothalamus and pituitary gland to release a chemical known as ACTH (adrenocorticotropic hormone). ACTH, known as the "stress hormone", stimulates the adrenal gland to produce and release cortisol.
A persistently high level of cortisol affects our health in many ways.
These changes are slow and incremental and are often only noticed once our health is significantly compromised.
Specific health problems include (but are not limited to):
We adapt to chronic stress through a variety of coping mechanisms, some of which may be genuinely helpful and some which may be maladaptive and further contribute to the negative impacts on our health in the long term.
When we are mindful we are more able to recognise potential stressors as we encounter them and to bring greater awareness to our internal experience of stress.