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  • Jacqui Snooks

So, What is the Autonomic Nervous System and How Does it Relate to my Stress Levels?

The Autonomic Nervous System (ANS) is responsible for controlling the internal bodily systems which function involuntarily, such as the lungs, heart and digestive system. It has two branches: the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system readies your body for emergencies, threat and danger, and the parasympathetic nervous system helps to restore rest, balance and calm. These two systems work together to regulate our stress levels as they ebb and flow through the course of our day to day life.

As it turns out, our nervous system responses are biologically and historically hard-wired to contend with threat; our survival as a species has depended on it.

Picture retrieved from Unsplash

This is because our prehistoric ancestors lived in constant fear of threat and danger. As we evolved, the flight-fight-freeze response developed to help brave wild weather and fight predators. Both then and now, when threat occurs, the ‘fear centre’ of our brain, called the amygdala, sends a distress signal to activate our sympathetic nervous system. When this occurs, we become flooded with stress hormones, the prefrontal cortex or ‘thinking’ centre of the brain is temporarily put on hold, and the fight-flight-freeze response takes over.

An example of sudden threat may be if a car suddenly veered onto the footpath, hurtling toward you at rapid speed. If this occurred, you wouldn’t stop and think about your next move. It is more likely that your heart would begin to race and your breathing and blood pressure would increase as your muscles tensed up in preparation for jumping out of the way. During this time, other autonomic processes, such as the digestive system, shut down to support the sympathetic physiological response.

The fight-flight-freeze response is switched off by the parasympathetic nervous system which brings balance once we realise the threat has passed.

When the car gains control, we realise are now safe. The brain stops sending panic signals to the nervous system. Our muscle tension, blood pressure, breathing rate and heart rate return to normal levels. When we are in this mode, we are not experiencing the fight-fight-freeze response anymore; harmony presides and balance is restored. This is often referred to as the ‘rest and digest’ state.

As we have seen, in evolution, our stress response was designed to help us survive. However, research shows that our sympathetic response can also be activated by psychological and mental stress. Our busy modern lifestyles often do not provide adequate time for our nervous systems to return to a balanced and calm state. Our bodies become chronically stressed and our minds overstimulated. This sympathetic overload reduces our ability to regulate our feelings and gain perspective when things go awry. Picture retrieved from Unsplash

Learning about the ANS and how to regulate to a calm state can be a game changer. There many internal and external resources you can use to build into your daily routine to ensure you don’t stay in a chronic overwhelm. Things such as mindfulness practice, regular long walks, yoga, going to the gym, catching up with a good friend, reflective writing are all practices which help to regulate our stress response. However, the key is discovering what works best for you, and embedding these practices into a daily self-care routine.

Of course, this can be difficult to maintain, particularly if we are not clear about what causes our stress in the first place. Seeking help from a trained professional may help you to discover your unique stress triggers, how to manage them, and how to regulate to a place of calm.

Jacqui Snooks is a registered counsellor and psychotherapist and director of Haven Counselling and Psychotherapy in Mornington. For more information please visit:

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