How does your body experience stress?

When we talk about stress, we have to talk about cortisol and the nervous system. As humans, when we experience something that is stressful, our body responds by releasing a natural hormone called cortisol. It is released by the adrenal glands as part of our fight or flight nervous system response.

The term “fight or flight” refers to one of the different nervous system responses we can experience and stems from the vagus nerve.

The vagus nerve, often described as the body’s “superhighway”, is responsible for turning off the fight or flight response. It’s called “vagus” because it wanders, like a vagrant, among the organs. It carries information between the brain and the internal organs and controls the body’s response to external stimuli. In this way, it is responsible for the mind-body connection.

Initially, it was understood that there were two parts of the nervous system: the para-sympathetic and the sympathetic, however an update to our understanding of the nervous system introduced the poly-vagal theory – named “poly” with the introduction of a third strand of the nervous system.

Here’s how stress plays a role in poly-vagal theory:

The sympathetic

The sympathetic part of our nervous system is responsible for the “fight or flight” experience. It is what happens when cortisol floods our body and we get ready to physically defend ourselves or run away as fast as possible.

You can identify if you’re in this state because it is often associated with high anxiety, jitters, restlessness, panic attacks, lack of sleep – basically any embodied experience that keeps you in a state of high alert and hyper-arousal. Once the fight-or-flight chemical reactions have begun, it can take our bodies 10–20 minutes to return to our pre-fight/pre-flight state and through long exposure to stress or trauma, we can in fact get “stuck” in this state and remain highly sensitive to external stimuli.

The para-sympathetic

The para-sympathetic nervous system is the calming aspect of our nervous mechanics. Here, the vagus nerve comes to the fore and works to balance the sympathetic part mentioned above.

However, when our external stimuli is in fact too stressful and our sympathetic state is overwhelmed, the dorsal branch of the vagus nerve can activate, putting us in a state of shutdown, collapse or most commonly known: freeze. In contrast to the hyper-arousal state mentioned above, this is the state of hypo-arousal.

This reaction causes a sense of numbness in the mind and body; our muscles can feel fatigued and we move into a state of immobility and dissociation. Here, the purpose is to numb the body to the external stimuli because, sometimes, it’s easier to be less sensitive to pain.

Our ‘window of tolerance’ – social engagement

This third nervous system response, coined the “social engagement” system or ‘window of tolerance’, is a mixture of activation and calming. It is defined best by Nichole Schnackenberg in her book, Bodies Arising“…there is a ‘window’ – a range of optimal arousal states within which emotions can be experienced as tolerable and experiences can be integrated – between the extremes of hypo- and hyper-arousal.”

The window of tolerance is the ventral vagal part of the nervous system. When you’re in this state, you feel like you can deal with whatever’s happening in your life. You might feel stress, but it doesn’t bother you too much.

Ideally, as humans we will gently move between our two hyper- and hypo-arousal states – being stimulated in stressful situations but also being able to self-regulate and self-soothe, returning to a calm, settled stated without getting stuck in either extreme.

Too much stress or a traumatic experience can shrink our window of tolerance, meaning that it may take very little to throw you off balance. However, through specialist help and support, individuals can expand their window of tolerance to ensure that they are more able to cope with challenges.

Our top tips for returning to your window of tolerance:

  • Breathing – this is the one part of the autonomic nervous system responses that we can control! Take deep, slow breaths with a focus on your belly rising and falling
  • Mindfulness – through things like journalling and meditation we can learn to be present in the here and now, and not “stuck” experiencing the past in the present
  • Compassion – similar to the above, learning to be compassionately curious about our emotional experience. If possible, inviting feelings in and recognising that we don’t need to over-identify with our emotional experience

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