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Stress and Breathing

It is commonly understood that in times of stress our breathing changes. Breathing rate increases as a natural response to a perceived threat - be that real or imaginary, it's basically telling you to 'get out of there' or 'get ready to fight'.

Today I'm going to delve into this a little more and look at some of the mechanisms behind what's going on.


  • Breathing changes under stress.

  • Stress is a natural response that results in physiological changes.

  • Our physiological responses are on a continuum between coma and panic.

  • Our breathing is determined by carbon dioxide levels, the diaphragm, and the brain.

  • Fast or slow breathings blood flow within the heart.

  • The brain will respond to blood flow change and carbon dioxide levels within the lungs.

  • Changing your breathing provides us with conscious control over our stress response via the lungs, diaphragm, heart, and brain axis.

What is Stress?

Stress responses are a totally natural response to a perceived threat. One should however consider stress as being a continuum on an autonomic arousal scale. With at one end being someone in a coma and at the other end being someone in a full-blown panic attack: with heart racing, pupils dilating, hyperventilating, increased adrenaline and other hormones. Along this continuum, we can place states such as being alert, feeling sleepy, being asleep.

However, when we commonly refer to stress,it is associated with being in a high level of autonomic arousal (increase heart rate, breathing, etc.). Unfortunately for us as a species, although we do not face the same type of life-threatening stressors as our ancestors, we still have this ancient mechanism ruling our lives. And unlike the animal kingdom, where they can let go of stress quickly once the threat has passed, we as a species can keep this threat alive with our thinking. Unfortunately, this can build to the point where it can start to feel pathological.

Breathing, body, and brain connection.

The relationship between the brain, body, and breathing is anchored through the diaphragm and carbon dioxide levels within the lungs. Carbon dioxide is the trigger for breathing because as the levels get too high it will trigger the diaphragm to relax resulting in exhalation.

The diaphragm is a large dome-shaped muscle located below the lungs and heart cavity. Although we don't normally pay much attention to it, it is a muscle that plays many roles in our health and function. Functionally as the diaphragm contracts the muscle flattens which creates a vacuum, this vacuum then allows air to be drawn into the lungs as it relaxes the opposite happens and the air is expelled. As you can imagine with around 22,000 breaths per day it is an extremely busy muscle.

However, something else happens during breathing, and that is as we inhale and the diaphragm moves downwards, the heart will also increase in size. Blood flow also slows down within the heart. This event then triggers a signal to the brain to say 'speed up the heart rate'. So if you inhale more than you exhale your heart rate will increase - and if you exhale more than you inhale the heart rate will slow. Like I said although you are not normally conscious of this muscle we can have some conscious control over its behaviour. Therefore the breath represents a bridge between the conscious and unconscious control of the body.

Breath control is therefore an important lever to help manage autonomic arousal, due to our ability to take some conscious control over its behaviour.

So in those moments of elevated stress that tried and tested advice of breathing slowly and deeply really has some physiological underpinnings.


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