Stress & Mindfulness


What is stress?

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.

Why do we experience stress?

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.

There are two types of stress

  1. Acute stress prepares us for fight-or-flight, and is generally short-term.
  2. Chronic stress is long term and is the main cause of stress-related health problems.

Stress causes chemical changes in the body that, left unchecked, can have negative effects on both mental and physical health.

Acute stress in detail

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.

Physical responses

  • Blood sugar levels rise.
  • Additional red blood cells are released (to carry extra oxygen).
  • Blood flow to large muscles of movement increases.
  • Peripheral blood vessels constrict.
  • The pulse quickens.
  • Blood pressure rises.
  • Digestion stops.

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 in detail

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.

  • Insomnia can result when the normal cyclical fluctuations of cortisol levels through the day and night are disrupted.
  • Certain immune functions are suppressed by high cortisol levels.
  • Wound healing time lengthens.
  • Bone formation decreases.
  • Cortisol promotes the synthesis of glucose from proteins in order to make more glucose available as fuel in response to stressful situations. This reduces lean muscle mass and increases blood sugar levels.
  • Cortisol also increases the deposition of abdominal fat and increases cravings for food, especially carbohydrates (sugars). This can set up a cycle of stress and overeating.

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):

  • high blood pressure
  • ischaemic heart disease (angina and heart attacks)
  • diabetes
  • depression
  • anxiety
  • headache
  • osteoporosis

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.

How can mindfulness help?

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.

  • We learn to pause, however briefly. In that pause, our pre-frontal cortex and parasympathetic nervous system are more able to mediate our habitual fight-or-flight response.
  • We can begin to respond rather than react. We are also able to recover more quickly and become more resilient in the face of stress and powerful emotions.
  • This expanded awareness is not limited to stressful situations. Mindfulness can allow us to reclaim many moments, not just the difficult ones.