Why your stress response can feel like it’s hijacking your personality, and what to do about it

Stress, Vagus nerves and Polyvagal Theory, made simple (really)

You may have heard the common wisdom that your nervous system has two main modes — calm/happy and Fight Or Flight.  In fact, you have three settings programmed into your Autonomic Nervous System (ANS), not two.

These settings are arranged as a simple hierarchy for dealing with threats to your safety.  In response to danger your most recently evolved system deploys first, and your most ancient system cuts in only as a last resort.

This ingenious arrangement, expounded by Dr Stephen Porges in his excellent book The Polyvagal Theory, explains everything from simple shyness to incapacitating trauma reactions, and why stress can impact so dramatically on your physical health.

As an owner of a human mind-body it’s important that you understand how this works, so you can have a healthy and low-stress life.

It all begins with something so familiar that you may not have thought of it as being a defence system…

Polyvagal Theory made simple

Level One:  Social Engagement

As a social mammal your first defensive response to danger is to try to negotiate your way out using your Social Engagement System.  Or, you might try to feel safe by comforting yourself with other people’s Social Engagement Systems — by co-regulating with reassuring people.

This behaviour is coordinated by the most recently evolved branch of your Vagus nerve.  This is a cranial nerve that regulates your heart (circulation), lungs (breathing), larynx (speech), jaw (chewing), pharynx (speech, swallowing), face (emotional expression), and middle ear (perception of voices).

All of these components are wired together into the same part of your brainstem, so they operate in concert.  That’s why you can read someone’s emotional state from their face, their voice or their breathing, or with the right equipment by measuring the electromagnetic signals from their heart.

If your Social Engagement System succeeds in getting you out of danger, you will return to your default physiological state — safety, or the digest and repair state in which physical resources are free to be used for healthy tasks like growth and recovery.  Your heart rate and breathing will be normal, your voice and eyes expressive, your hearing balanced, and your body will be working well.

However, if it is unable to resolve the challenging situation or soothe your soul, it down-regulates and hands over to your Level Two defence mechanism…

More science…

  • This is your mammalian or Ventral Vagus Complex at work, a major player in your Parasympathetic Nervous System.
  • It’s mostly myelinated and evolved to coordinate suckling behaviour and parent-baby attachment in mammals.  It regulates the muscles of your head and neck, and the organs above your diaphragm.
  • When enabled and functioning well, it produces a physiological state of safety — the ‘digest and repair’ state.
  • Ventral Vagal tone is the foundation of emotional resilience.
  • Respiratory Sinus Arrhythmia, a measure of healthy heart rhythm, provides a good index of Ventral Vagal tone.

Level Two:  Fight Or Flight = mobilisation

When your Social Engagement System throws its hands in the air, your Fight Or Flight mechanism takes over.

This is your Sympathetic Nervous System (SNS) in action.  Its speciality is keeping you safe by mobilising you to run away from, or fight off, a threat.

That’s why your heart speeds up to pump extra blood, with its cargo of oxygen and glucose, to the major muscles of your body.  You may sweat to cool the mechanism which would otherwise overheat from activity.  Energy-intensive tasks like digestion and analytical cognition will slow or stop.  Your focus will narrow onto the source of threat.

Your Social Engagement System is now off or sputtering, so your voice may go quiet or monotone, your throat may tighten, you may lose expressiveness around your eyes, and your perception of human voices may reduce (though low frequency sounds typical of predators, machinery and background noise may seem louder).  You may feel suspicious, often needlessly, of others’ intentions.

This is all normal.

If your Flight Or Flight system looks like it’s not going to be able to resolve the situation either, perhaps because you are unable to physically escape or your assailant is more powerful than you, it too cuts out and escalates the issue for management by the ultimate survival specialist, your Level Three defence system…

More science…

  • When activated in response to environmental cues of danger, your Sympathetic Nervous System (SNS) suppresses the function of the ventral and dorsal Vagal pathways and, consequently, the functioning of all organs and muscles regulated by these nerves.  This is why stress has such an impact on health and recovery.
  • When your ANS judges the environment to be safe, the Ventral Vagus is capable of modulating the response of your SNS to enable ‘mobilisation without fear’, such as play fighting.
  • Your intrinsic heart rate is about 90 beats per minute.  In a safe situation the Ventral Vagal brake dampens this to 60-70 beats per minute, by coming on when you exhale (breathe out).  During inhalation (breathing in) and/or when your SNS takes over, the Ventral Vagal brake comes off, allowing your heart to speed up.

Level Three:  Freeze = immobilisation

Under acute threat to your life (or perception of such) and when Fight Or Flight is not going to be effective, your third and most ancient defence system comes online — the Freeze response.

It’s a survival program managed by a different, primitive branch of your Vagus Nerve.  It deploys an old, trusty method of defense — immobilisation.  Just like the mouse hanging limp in the jaws of the cat, playing dead, this system shuts down movement and most signs of life.

Your breathing and heart will slow dramatically, your muscles will soften, you may pass out or feel frozen in place, and your pain threshold will increase.  You might defecate — this is the origin of the expression “To sh*t oneself“.  You might mentally dissociate (lose presence) from what’s happening, to reduce its impact.

As your Social Engagement System is still switched off, it means blank eyes, no talking, and poor perception of human voices.

In this state it is not possible to fight or flee.  Victims of life-threatening events often question “Why didn’t I put up a fight or run when I had a chance?”  Well, because you couldn’t.  Your ANS made the judgement for you that the situation was a Level Three, requiring immobilisation as the best chance for your survival.  It physiologically prevented you from mobilising, and was very serious about it.  You simply weren’t in charge.

More science…

  • This is your reptilian or Dorsal Vagus at work, also part of your Parasympathetic Nervous System.
  • It’s mostly unmyelinated and serves organs below your diaphragm such as your stomach (including stomach acid), intestines and sexual organs.
  • When the ANS judges the environment to be safe, the Ventral Vagus is capable of modulating the response of the Dorsal Vagus to enable ‘immobilisation without fear’, such as in hugging or sexual intimacy.

Where things go wrong

This is all as it should be.  This three-part safety system is a very clever operational hierarchy, honed by evolution over millions of years.  It functions automatically because it’s designed to protect you.  It’s not a matter of personality.  It really isn’t about you at all.

Difficulty arises, though, if your ANS gets ‘stuck’ at a defence level, leaving you unable to properly digest, repair, or socially engage, or when it habitually misreads everyday situations as threatening and switches on disruptively.

It may be difficult to perceive whether you are stuck in a defence mode if it’s chronic and familiar.  The simplest test is this:  Are you calm, reasonably cheerful, and fairly confident and engaged, the majority of the time?  Yes?  Great!

If not, you are in one or other defence mode, with its associated impacts on your health, cognition, relationships and joy of life.

More specifically…

It is a good thing to spend time co-regulating your nervous system with nice friends at Level One, Social Engagement.  However, if you are over-using this system for defence purposes you may experience yourself fawning or kowtowing more than you would like, rather than relating to others confidently as an equal.  In other words, being a confrontation-avoidant people-pleaser — probably in an attempt to prevent yourself from switching down a gear into Level Two, Fight Or Flight.

The most common problem in modern urban cultures is to be stuck at, or to over-use, Fight Or Flight — mobilisation.

You may experience this as generalised anxiety (racing thoughts, catastrophising), social anxiety (shyness, avoidance), stress (pressure or overwhelm), or anger (being hostile or reactive, damaging relationships).

Because your nervous system regulates organ function, stuck at Level Two you may also experience physical problems related to your heart, voice, swallowing, hearing (especially voices), sexual function, and stomach or bowel.  Injuries and illness may be slow to heal.

It can eventually also trigger a descent into depression.

Dorsal Vagus nerve immobilisation Least common but quite debilitating is to be stuck at Level Three, immobilisation, a manifestation of Post Traumatic Stress Disorder (PTSD).  You may experience being triggered into full or partial immobilisation by everyday events that in some way resemble the original trauma.  You may feel dissociated, avoid engaging with people, or appear to others to be ‘not present’.

Friends and family may be confused and frustrated by their inability to soothe you and bring you out (using their Social Engagement Systems), because in immobilisation your nervous system is minimally responsive to interpersonal signals of care.

Physical systems that may be affected include regulation of your blood pressure, heart function, bowel and digestive function, cognition and sexual function.

Your general health may falter in many puzzling ways as a result of the chronic down-regulation of basic physiological functions like breathing, circulation, digestion and assimilation of food, and tissue repair.


What can you do for yourself?

Fortunately, this is where psychological therapy – or really, education – comes to the rescue.  It sets out to retrain your Mobilisation and Immobilisation systems to respond appropriately only when needed, and to stay offline the rest of the time.  You can learn how to make things that used to feel threatening much less triggering, and to better self-regulate.

The goal is to spend most of your life feeling safe in the digest and repair physiological state, with a skillful Social Engagement System dominating proceedings.

Other interventions can help too, such as pranayama yoga or yogic breathing techniques, which directly and very beneficially modulate the function of the nervous system, and breath-centric mindful movement practices such as yoga asana and Tai Chi.

Nutrition can have a big impact by supplying the raw materials your nervous system requires to function well, and by reducing inflammation.  Diet also affects the microbiome in your gut, which science is now showing has surprisingly profound effects on nervous system reactivity and brain function.

Environment is key.  Your nervous system needs biological safety cues to settle down into safety mode.  This means quiet, greenery and appropriate layout.  (See below for more details.)

Also, of course, companionship with others who have healthy Social Engagement Systems is extremely helpful.  That means people who are calm, reasonably cheerful, and fairly confident and engaged, the majority of the time.

What can you do for others?

Enhancing others’ health, resilience and creativity by optimising their nervous system settings is all about making them feel safe, not just removing objective threats.  Concrete walls and checkpoints make a workplace objectively safe, yet trigger our nervous systems into a chronically defensive state.  Remember it’s our nervous systems that need environmental safety cues, not our intellects.

This means designing environments that are…

Quiet.  No thundering air-conditioning systems or other low-frequency sound pollution.  Use soft furnishings to absorb sound.  If you play music use a light, prosodic playlist, not bassy tunes or radio advertising and ‘news’.

Green.  Buildings need plants, or at the very least views of greenery.  People who live in apartments with trees around them feel less anxious than those living in identical apartments in adjacent blocks without trees.

Cosy.  Buildings need some nooks.  Refer to the tradition of Feng Shui to guide layouts.  It’s all about optimising environments to generate a feeling of safety and relaxation.

Socially secure.  An employee or school child who feels continually evaluated, or under threat of punishment or expulsion from the tribe — that is, biologically unsafe — will be in a chronic physiological state of defence and thereby unable to manifest their cognitive and creative potential.  They will not be resilient.

So, make a point of creating socially connected, constructive employment and educational cultures, and a home environment for yourself and your family based on the same principles.


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