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  • Writer's pictureSusan Woodward

The Role of the Autonomic Nervous System in Chronic Fatigue Syndrome / ME

Updated: Apr 13, 2022

One of the key components to 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 Autonomic Nervous System is a part of the Nervous System that controls and regulates bodily functions/Body Systems without any conscious recognition or effort by us. It has influence over muscles, glands and organs throughout the body and controls a range of functions such as heart rate, respiratory rate, salivation, digestion, perspiration and urination.

The ANS comprises two antagonistic sets of nerves: The Sympathetic Nervous System and the Parasympathetic Nervous Systems.

Seesaw picture representing the 2 branches of the autonomic nervous system how they work synergistically

When our brain perceives a threat, the Sympathetic branch of our Nervous System kicks in, pumping blood to our muscles/ heart/brain so we are ready to fight or run for our lives -- commonly referred to as the ‘Fight or Flight’ mode.

When the threat has passed, the Parasympathetic branch of the Nervous System takes over to calm everything down – commonly referred to as the ‘Rest, Heal & Digest’ mode.

In healthy and low stress individuals this switching between the Parasympathetic and Sympathetic Nervous Systems works synergistically via a mechanism called The HPA Axis. This Hypothalamic- Pituitary-Adrenal Axis operates via an increasing or decreasing feedback loop which either stimulates or inhibits the release of certain stress hormones in particular, Cortisol and Adrenaline.

However, in chronically stressed individuals the HPA Axis can become desensitised to the calming effects of the Parasympathetic branch leading to Sympathetic Nervous System Dominance. It is this Sympathetic Dominance which can result in adrenal overload and the physical, mental and emotional exhaustion experienced in CFS/ME.

Whilst this 'Fight or Flight' mechanism can be life-saving in the short term (up-regulating heart rate, blood pressure and blood sugar levels to allow oxygen and vital nutrients to reach our muscles, heart and brain) over the long term, this up-regulation of Body Systems can lead to an array of unpleasant symptoms: palpitations, light-headedness, dizziness, shakiness, irritability, intense hunger, energy crashes, frequent urination, anxiety and sleep disruption. Conversely, other Body Systems normally controlled by the Parasympathetic System (digestive/immune/hormonal) are down-regulated which again, over time, lead to an array of symptoms and digestive, immune and hormonal complications.

This Sympathetic Dominance which leads to imbalance in so many of the Body’s Systems is why we see such a varied and wide-ranging symptom pattern in CFS/ME.

Getting out of Sympathetic Dominance is crucial in order to achieve symptom reduction and to allow the body to regain its natural balance (levels of homeostasis) – only then is the body in a place where it can start to heal.


What can we do to get out of Sympathetic Nervous System Dominance?

> Identify and support the body systems most out of balance.

> Eat a diet that supports healthy blood sugar levels & does not increase Cortisol production.

> Identify and correct nutritional deficiencies to support adrenal, thyroid and energy production.

> Learn tools/techniques to reduce anxiety and calm our stress response.

> Improve sleep quality.

> 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.

> Identify and correct digestive issues such as gut dysbiosis and gut permeability to reduce burden.


Predisposition to CFS/ME

So, with the endemic levels of stress we all experience in today's relentless digital age, 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 sensitive gene and the 'highly sensitive' personality which shows some people are hard-wired to process and react to stress differently to most other people – life events will have a deeper impact upon them.

A common denominator I see in all my 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, endless 'To Do' lists, their minds are always processing, strategising worrying, they find it more challenging to shut off, to say no and can have a skewed perception of self-care. Awareness around these energy depleting personality subtypes is important in being able to recognise and change behavioural patterns that might be driving a negative stress response and contributing to Sympathetic Dominance.

As can be seen from the above, taking a multi-faceted approach is essential to regain balance in the body and to achieve lasting symptom improvement. Working with a health practitioner who understands this is key.

Click here for detailed information on the CFS/ME Reboot Programme.

References Cvejic, E., Sandler, C.X., Keech, A., Barry, B.K., Lloyd, A.R. and Vollmer-Conna, U. (2017) Autonomic nervous system function, activity patterns, and sleep after physical or cognitive challenge in people with chronic fatigue syndrome, Journal of Psychosomatic Research, 103, 91-94.

Fisher, J.P., Young, C.N. and Fadel, P.J. (2010) Central Sympathetic Overactivity: Maladies and Mechanisms, Autonomic Neuroscience, 148 (1-2): 5-15.

Johnson, C. (2017) Chronic Fatigue Syndrome Studies link Autonomic Nervous System Problems to the Brain, HelathRising Available: syndrome-link-autonomic-nervous-system-problems-to-brain/

Martinez, M., Mora, T., Vargas, A., Fuentes-Iniestra, M., Martinez-Kavin, M., (2014) Sympathetic nervous system dysfunction in fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and interstitial cystitis: a review of case-control studies, Journal of Clinical Rheumatology, 20, 3: 146- 50.

Orjatsalo, M., Alakuijala, A. and Pertinen, M. (2017) Autonomic Nervous System Functioning Related to Nocturnal Sleep in Patients with Chronic Fatigue Syndrome Compared to Tired Controls, Journal of Clinical Sleep Medicine.

Robinson, L.J., Durham, J., MacLachlan, L. and Newton, J.L. (2015) Autonomic function in chronic fatigue syndrome with and without painful temporomandibular disorder, Fatigue: Biomedicine, Health and Behaviour, 3, 4.

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