Nervous system dysregulation


One of the key contributors to mental health issues is a dysregulated nervous system. It affects, and is affected by, many of the other contributors listed on this website. 

A dysregulated nervous system will often cause us to respond (thoughts, feelings, behaviour) in an apparently inappropriate (disproportional) way to an event, person, or situation, either by under-reacting or over-reacting.

It is usually caused by unresolved, unfinished stress responses from our past.

It can also be caused by other psycho-spiritual, lifestyle-behavioural and biochemical factors as listed below.

It can manifest as mental health symptoms (such as depression, anxiety and panic, sleep issues, poor memory, poor concentration and attention, irritability, exhaustion), and inappropriate behaviour (such as rage outbursts, passive aggression, being shut down, lying, being vindictive or particularly argumentative), which can further exacerbate problems with relationships and mental health.


What is the nervous system?

The nervous system is a complex collection of nerves and specialised cells known as neurons that transmit signals between different parts of the body. It is essentially the body’s electrical wiring”Nervous System: Facts, Function & Diseases By Kim Ann Zimmermann – Live Science Contributor February 14, 2018,and%20the%20peripheral%20nervous%20system.[accessed July 3rd, 2020]

When we talk of a dysregulated nervous system, we are referring to the autonomic nervous system, which causes us to think, feel and behave in ways that are driven by unconscious patterns and which generate automatic responses.

What does the autonomic nervous system do?

The autonomic nervous system’s job is to keep us safe and alive.

The autonomic nervous system is divided into two systems: the sympathetic, and the parasympathetic 

  • The sympathetic regulates our fight and flight response (which enables us to either fight, or run when in danger)
  • The parasympathetic regulates our rest and digest response (which enables us to recover, regenerate and digest our food)
  • Both sympathetic and parasympathetic are essential to keeping us safe

The autonomic nervous system and the polyvagal theory

  • More recently, Dr. Stephen Porges has developed a more nuanced understanding of the autonomic nervous system.
  • His research shows that the parasympathetic system has more to it than the rest and digest mode.
    • It also has a freeze or shutdown mode, mediated by the dorsal vagus, which allows us to freeze and immobilise when we are in danger but can neither fight nor flee (such as during childhood abuse).
      • This is our most primal threat response, and comes from the most primitive part of our brain, our reptilian brain. 
    • It also has a social engagement system, mediated by the ventral vagus (hence poly-vagal), which allows for social engagement and connection with others in a constructive way when we feel safe. 
      • This system is linked to our mammalian brain.
      • It ensures our survival, as mammals depend on connection with other mammals to thrive. 
  • The polyvagal theory reframes our understanding of the autonomic nervous system as comprising (in descending chronological evolutionary order):
    1. Social engagement mode
      • mediated by the ventral vagus
      • links to our prefrontal cortex and mammalian brain (limbic system)
      • part of our parasympathetic nervous system
    2. Fight/flight mode
      • links to our mammalian brain (limbic system)
      • part of our sympathetic nervous system
    3. Freeze mode
      • mediated by the dorsal vagus
      • links to our reptilian brain (limbic system)
      • part of our parasympathetic nervous system
  • Mixed response:
    • Sometimes, the social engagement system tempers the other two (fight-flight and freeze) to create situations of safety
    • Rough housing/play/wrestling: fight or flight tempered by our social engagement system
    • Intimacy: freeze response tempered by our social engagement system 

What is a dysregulated nervous system? 

Our nervous system is a fine tuned, sophisticated system designed to ensure our survival. When we encounter threat, it adapts its response — and consequently our behaviour — to our circumstances.

Depending on our circumstances, it may activate:

  • our sympathetic system, if we need to fight or flee
  • our parasympathetic system, if we need to rest and digest
  • our dorsal vagus, if we need to freeze 
  • our ventral vagus, if we need to engage and connect with others

We are constantly and unconsciously reading our environment for cues of safety, or cues of danger, a process Dr. Stephen Porges calls “neuroception”, and adjusting our behaviour to stay safe, depending on our circumstances.

If our nervous system is well regulated, we will respond appropriately to our circumstances and threats (thoughts, feelings, and behaviours), but once the threat is gone, our nervous system should return to homeostasis.

If, for instance, you are in a very stressful situation, with financial worries or difficult life circumstances for example, and are feeling extremely stressed and anxious, then your nervous system is responding appropriately to your external circumstances. Go to stress in order to find out more about how your current stress could be impacting your mental health and how to deal with it. 

If our nervous system is dysregulated however, it is reacting to present circumstances on the basis of past stressors rather than current ones.

  • It gets stuck in a threat response, even once the threat has passed
  • So we still have physiological and biochemical manifestations of threat, even though our circumstances are safe
  • There is then a discrepancy between our physiological perception of threat (with the full biological cascade of neuroendocrine dysregulation), and our external reality 

When our nervous system is dysregulated, we will have faulty neuroception which will cause us to over-react or under-react inappropriately, due to cues from our internal physiology which are mismatched with external circumstances.

Symptoms of a dysregulated nervous system

A dysregulated nervous system can cause mental health symptoms such as anxiety, PTSD, OCD, ADHD, depression, insomnia, poor attention, poor memory, addiction, exhaustion

It can lead to dysfunctional, inappropriate, or violent behaviour characterised by over-reaction (outbursts, tantrums, anger) or under-reaction (passivity, catatonia, withdrawal, shutting down) towards people, events and situations.

Biochemically, it is usually accompanied by a dysregulated HPA axis, or imbalanced stress hormones

This is because a dysregulated nervous system is caused by the same things that dysregulate the HPA axis and stress hormones, and the biochemical consequences of a dysregulated nervous system is a dysregulated HPA axis and imbalanced stress hormones. 

Causes of a dysregulated nervous system

A dysregulated nervous system can be caused by a threat response from the past that does not complete the full cycle and does not get “finished” so it stays in our system, causing thoughts, feelings and behaviour that would be consistent with a threat even though there is none. 

Or in the case of biochemical threats, as Dr. Naviaux points out in his “cell danger response”, our bodies go into “defense” mode and get stuck there, even when the threat has passed, due to the cascade of neuroendocrine and inflammatory responses which create their own dysregulation in our physiologies.

There are many factors which can contribute to a dysregulated nervous system:

Psycho-spiritual factors:

Lifestyle-behavioural factors:

Biochemical factors:

While we don’t often think of biochemical factors causing a dysregulated nervous system (we tend to think of the psychological and lifestyle factors), in fact, our bodies interpret threat in the same way, whether it is psychological or physiological. 

Both cause a similar neuroendocrine chain reaction. So if our bodies are under chronic attack by toxins such as heavy metals or mould; infections such as Lyme disease or bartonella; or if our gut is full of pathogens, our bodies can interpret this as a vital threat to our physiology. 

This can cause our nervous system to go into overdrive and get “stuck”, spewing out stress hormones which unchecked, can cause systemic inflammation.

On a cellular level, this parallels Dr. Naviaux’s cell danger response, in which cells get stuck in a threat response even once a threat has passed. Naviaux R. K. (2014). Metabolic features of the cell danger response. Mitochondrion, 16, 7–17.[accessed July 3rd, 2020], Dr. Neil Nathan, “Toxic: Heal Your Body from Mold Toxicity, Lyme Disease, Multiple Chemical Sensitivities, and Chronic Environmental Illness” October 2018, Victory Belt Publishing

Consequences of a dysregulated nervous system

A dysregulated nervous system can cause mental health symptoms such as depression, anxiety, insomnia, poor attention and poor memory, but can also lead to behaviours which are unhelpful to living a healthy, balanced life, and cause:

  • Difficult relationships, whether with colleagues, partners, friends or family
  • Poor life choices (such as indulging in addictive substances or behaviours) due to trying to avoid the discomfort we feel from our nervous system dysregulation and ensuing mental health symptoms
  • Acting in ways which are short-sighted, unhealthy and destructive to ourselves and others because our thoughts and behaviours are ruled by our limbic system (the more primitive, emotional, reflexive part of the brain) rather than our prefrontal cortex (the more rational, executive, organised and planning function of the brain)