The role of the autonomic nervous system in CFS/ME

One of the key components in understanding chronic fatigue syndrome/ME is to understand the role of the autonomic nervous system (ANS), and how an altered or dysfunctional ANS may be creating and/or exacerbating the symptoms associated with CFS/ME.


The ANS is a part of the nervous system that controls and regulates our body’s internal organs without any conscious recognition or effort by us. It influences muscles and glands throughout the body and controls a range of functions such as heart rate, breathing, salivation, digestion, perspiration, and urination.

The ANS comprises two antagonistic sets of nerves - the sympathetic nervous system and the parasympathetic nervous systems. When our brain perceives a threat, the sympathetic branch of our nervous system kicks in, pumping blood to our muscles, heart, and brain so we are ready to fight or run for our lives; often referred to as the 'fight or flight' mode.

When the threat has passed, the parasympathetic branch of the nervous system kicks-in to calm everything down. Often referred to as the 'rest, heal, and digest', or 'feed and breed' mode.

In healthy, low-stress individuals, this switching between the parasympathetic and sympathetic nervous systems works synergistically via a mechanism called the HPA axis (the hypothalamic/pituitary/adrenal axis), which operates on either increasing or decreasing feedback loops, either stimulating or inhibiting the release of certain stress hormones; in particular, cortisol.

Exhausted man

In chronic stress, however, the HPA axis can become desensitised to the calming effects of the parasympathetic nervous system, leading to sympathetic nervous system dominance and adrenal overload. This results in the physical, mental, and emotional exhaustion experienced in CFS/ME. In simpler terms, being stuck in 'fight or flight' stress mode.

In this sympathetic nervous system dominance, the functioning of all the body's systems is either up or down-regulated, leading, over time, to the wide-ranging number of random symptoms experienced in CFS/ME.

Getting out of sympathetic nervous system dominance is crucial to get symptom reduction, and also to allow the body to rebalance and regain its natural levels of homeostasis - only then can the body start healing.

How can we get out of sympathetic nervous system dominance?

  • Eat a diet that supports healthy blood sugar levels and does not increase cortisol production.
  • Identify and correct nutritional deficiencies.
  • Identify and support the body systems most out of balance.
  • Improve sleep quality.
  • Learn tools/techniques that can lower your anxiety and stress response.
  • Identify and correct digestive problems such as gut dysbiosis and gut permeability.
  • Identify and correct food sensitivities.
  • Identify and break negative behavioural patterns that drive us into 'fight and flight' mode.
  • Deal with unprocessed trauma/grief that can be driving a negative stress response.

So with the endemic levels of stress we all experience, why isn't everyone tipping over into CFS/ME?

Well, genetics will play a role in a predisposition to this illness. There is interesting research around the 'highly sensitive' personality and the sensitive gene which shows some people are hard-wired to process and react to stress differently to others. 

A common denominator seen in CFS/ME clients is a type A personality: The over-achiever, the perfectionist, the worrier, the helper. These personalities tend to be self-critical with very high expectations of self, with endless 'to-do' lists. Their minds are always processing, thinking, worrying, or strategising, and they find it challenging to shut off.  Awareness around these energy-depleting personality subtypes is paramount in changing behavioural patterns that might be driving a negative stress response.

As can be seen from the above, working with a nutritional therapist who takes a multi-faceted approach, way beyond nutrition, will be essential in supporting this very complex and multi-factorial condition.

Nutritionist Resource is not responsible for the articles published by members. The views expressed are those of the member who wrote the article.

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London N8 & EC3M
Written by Susan Woodward, (Replenish Nutrition), Dip CNM mBANT rCNHC
London N8 & EC3M

Susan Woodward is a Registered Nutritional Therapist who specialises in supporting Chronic Fatigue Syndrome, ME, Fibromyalgia, Digestive and Hormonal health. Rather than look at symptoms in isolation, Susan’s focus is on identifying and supporting underlying imbalances in the body and the root cause of illness.

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