What is Chronic Fatigue Syndrome?
Chronic Fatigue Syndrome (CFS / ME) is a long-term health condition characterised by profound fatigue and reduced physical or mental capacity following activity.
Key features often include:
- Severe fatigue that does not improve with rest
- Post-exertional malaise (PEM) — worsening symptoms after physical or mental activity
- Cognitive issues such as brain fog and poor concentration
- Sleep disturbances and unrefreshing sleep
- Muscle and joint pain
- Sensitivity to light, sound, or temperature
CFS can range from mild to severe. In severe cases, individuals may struggle with everyday tasks and may spend much of their time resting or confined to bed.
Why Does Chronic Fatigue Syndrome Develop?
There is unlikely to be a single cause of CFS. Instead, research suggests that the condition may arise from a combination of biological, neurological, immune, and environmental factors. These systems interact with each other, meaning disruption in one area may influence others.
Below are some of the key mechanisms that have been explored in research.
Immune System Dysregulation
Immune molecules called cytokines may be elevated in some cases. These signalling molecules help regulate immune responses but can also contribute to symptoms such as fatigue, muscle pain, and flu-like feelings when present at higher levels.
Some researchers have also suggested that CFS shares similarities with autoimmune conditions, where the immune system becomes dysregulated and mistakenly targets the body’s own tissues.
Mitochondrial and Energy Production Dysfunction
Research has suggested that people with CFS may experience impaired mitochondrial function, meaning their cells may struggle to produce energy efficiently. This could explain why even small amounts of physical or mental effort can lead to profound exhaustion.
If the body cannot produce sufficient cellular energy, the result may be:
- Severe fatigue
- Muscle weakness
- Slow recovery after exertion
Autonomic Nervous System Dysfunction
Many people with CFS experience symptoms consistent with dysautonomia, meaning the ANS may struggle to regulate these functions effectively.
This can lead to symptoms such as:
- Dizziness or lightheadedness
- Heart palpitations
- Temperature sensitivity
- Digestive issues
- Difficulty concentrating
Viral and Infectious Triggers
Viruses commonly associated with the onset of CFS include:
- Epstein–Barr virus (EBV)
- Human herpesvirus 6 (HHV-6)
- Cytomegalovirus (CMV)
- Enteroviruses
While these infections may not remain active, they may trigger long-term immune dysregulation or inflammatory responses.
Gut Microbiome Imbalance
Research suggests that individuals with CFS may have alterations in their gut microbiome, potentially affecting immune regulation and inflammation.
Gut-related symptoms that may occur include:
- Bloating
- Digestive discomfort
- Food sensitivities
- Altered bowel habits
Hormonal and Endocrine Disruption
For example, some research has identified abnormalities in cortisol, the hormone responsible for regulating the body’s stress response. Disruption in cortisol rhythms can affect energy levels, sleep patterns, and immune regulation.
Thyroid hormone imbalance and fluctuations in sex hormones may also contribute to fatigue, cognitive difficulties, and changes in metabolism.
Emotional Stress and Trauma
Chronic activation of the body’s stress response may place significant demands on energy systems and recovery processes. Over time, this may contribute to fatigue, nervous system dysregulation, and increased sensitivity to stress or exertion.
While emotional factors are not the sole cause of CFS, they may interact with other biological mechanisms to influence symptoms and recovery.
Common Symptoms of CFS
Although symptoms vary between individuals, the most commonly reported symptoms include:
- Persistent fatigue that does not improve with rest
- Post-exertional malaise (PEM)
- Muscle pain and joint pain
- Headaches
- Brain fog and cognitive difficulties
- Sleep disturbances
- Sensitivity to light, sound, or temperature
- Dizziness or palpitations
- Digestive issues
These symptoms can fluctuate over time, often with periods of improvement followed by symptom flare-ups.
Understanding CFS as a Whole-Body Condition
Chronic Fatigue Syndrome is increasingly recognised as a complex, systemic condition involving multiple biological systems.
Rather than being caused by a single factor, CFS may involve an interplay between:
- immune system dysregulation
- nervous system imbalance
- energy metabolism dysfunction
- hormonal disruption
- gut health changes
- environmental or emotional stressors
Understanding how these systems interact can help provide a more complete picture of why symptoms occur and why recovery can vary from person to person.
If you are experiencing symptoms similar to those described in this article and would like further guidance, you are welcome to get in touch with the practice for advice.
Theories Behind Chronic Fatigue Syndrome: A Functional Medicine Approach
Functional medicine looks at CFS as a multifactorial condition, meaning that its causes could stem from various systemic dysfunctions, rather than a single, identifiable pathology. From this perspective, the body is seen as an interconnected system, and imbalances in one area could trigger a cascade of other problems, leading to chronic fatigue. Here are several mechanisms theorised to contribute to CFS based on current research:
Immune System Dysfunction
There seems little doubt that CFS is associated with immune system dysregulation. Research has indicated that individuals with ME/CFS often exhibit heightened immune responses, such as inflammation or the activation of cytokines, which are molecules that help regulate immune responses. These immune system imbalances could lead to chronic low-grade inflammation, which might be a key factor in the fatigue and pain experienced by those with CFS.
Studies from UK researchers have explored the idea that CFS may share common pathways with autoimmune conditions. In these conditions, the immune system mistakenly attacks the body’s own tissues. The dysfunction in immune signaling might impair the body’s ability to repair itself or recover from illness, contributing to the persistent fatigue.
Mitochondrial Dysfunction
The mitochondria are the powerhouses of our cells, responsible for producing energy. A number of studies have pointed to mitochondrial dysfunction as a possible cause of the overwhelming fatigue in CFS. In a functional medicine context, this is often referred to as energy dysregulation at the cellular level. Research from the UK has suggested that people with ME/CFS might have mitochondrial damage or dysfunction, leading to an inability to generate sufficient energy for normal bodily functions. This energy deficit could explain why physical or mental exertion exacerbates the symptoms of CFS.
This theory also ties into metabolic disturbances that have been observed in some patients, suggesting that the body is unable to properly utilize nutrients or oxygen to fuel cellular processes, leading to the characteristic exhaustion and muscle pain.
Neurological Dysfunction
Another theory gaining traction is that CFS involves abnormalities in the brain and nervous system, particularly in how the body perceives and processes fatigue. Dysregulation in the autonomic nervous system (ANS), which controls involuntary body functions such as heart rate and blood pressure, may be a key factor in CFS. Dysfunction in the ANS could contribute to the fluctuating energy levels and cognitive dysfunction seen in CFS patients.
Research from UK-based studies has shown that individuals with CFS often report symptoms consistent with dysautonomia, such as dizziness, lightheadedness, and an inability to regulate body temperature. The autonomic nervous system may also play a role in the “brain fog” commonly experienced in CFS, which includes symptoms like poor concentration, memory problems, and confusion.
Chronic Infections
Many sufferers with CFS report the beginning of their illness being precipitated by a period of illness. Given that most of us experience illness at various points throughout our lives, this begs the question why do some people have trouble recovering from their illnesses? It would seem to again point to their being multiple triggers.
There are some viruses and pathogens which have been commonly linked to the development of CFS. These include:
- Epstein-Barr virus – a member of the herpes virus family, it is one of the most commonly implicated viruses in CFS. It is known to cause infectious mononucleosis (mono), and reactivation of EBV is frequently observed in patients with CFS/ME. Research suggests that chronic EBV infection may lead to prolonged immune activation and dysfunction, again a common feature of CFS.
- Human Herpes Virus 6 (HHV6) – reactivation of this virus is often linked to neurological symptoms and immune dysfunction. It can affect the central nervous system causing inflammation in the brain.
- Cytomegalovirus – another herpes virus, in CFS it commonly leads to inflammation, immune dysfunction and general CFS symptoms.
- Enteroviruses – often seen in post viral fatigue, these viruses can persist long-term in tissues resulting in long-term immune system activation, muscle pain and fatigue.
- Borrelia burgdorferi (Lyme’s disease) – Lyme’s disease is caused by a bacterium, that can cause ongoing persistent low grade infections giving rise to symptoms similar to CFS.
Emotional and Psychological Impact
Living with an autoimmune disease can take an emotional toll. The chronic pain, fatigue, and unpredictability of symptoms can lead to feelings of frustration, anxiety, and depression. Additionally, the impact on physical appearance—such as rashes, hair loss, or joint deformities—can affect self-esteem and body image.
Living with auto-immune conditions can be extremely challenging and lonely, especially for those who are unsure where to turn for support. If you, or someone close to you, would like to discuss the health challenges you are experiencing please get in touch here (link to contact page).
References:
- James, W., & Hamilton, R. (2019). Autoimmune Diseases and Their Triggers. The Lancet. Retrieved from https://www.thelancet.com/
- Shoenfeld, Y., et al. (2012). Autoimmune Diseases: Triggers and Environmental Factors. Journal of Autoimmunity, 39 (3), 200-206.
- Liao, B., et al. (2021). Genetic Factors in Autoimmune Diseases. Frontiers in Immunology. Retrieved from https://www.frontiersin.org/
Gut Microbiome Imbalance
The role of the gut microbiome in overall health has become a major focus of research in recent years. There is growing interest in how the gut microbiome may influence systemic inflammation and immune function. Imbalances in the gut flora could contribute to dysregulation of the immune system, which, as mentioned earlier, is a key theory in the development of CFS.
Some studies suggest that the microbiome in people with CFS may differ significantly from that of healthy individuals, particularly in relation to the diversity and balance of microbial species. Research has also indicated a potential link between gut health and neurological symptoms, supporting the idea that a dysfunctional gut-brain axis might be involved in the development of CFS.
Hormonal Imbalances
Another potential mechanism underlying CFS is hormonal dysregulation. The body’s endocrine system, which produces hormones to regulate various functions, is almost certainly disrupted in CFS patients. For instance, research has shown abnormalities in cortisol levels, which is the hormone responsible for managing stress. Chronic stress, which can be both physical and psychological, might lead to persistent high or low cortisol levels, disrupting the body’s natural rhythm and contributing to fatigue.
Additionally, thyroid dysfunction has been observed in some CFS patients, which can also lead to fatigue, weight changes, and cognitive impairments. Imbalances in sex hormones, such as estrogen and progesterone, may further exacerbate fatigue, especially in women.
Emotional Trauma as a Trigger
Emotional trauma is increasingly recognised as a potential trigger for CFS. Trauma—whether physical, emotional, or psychological—can have long-lasting effects on the body’s stress response system. Traumatic events, such as abuse, a history of chronic stress, or a significant life event, can overwhelm the body’s ability to cope, leading to systemic imbalances.
Emotional trauma may lead to dysregulation in the autonomic nervous system (ANS), contributing to symptoms of CFS like brain fog, fatigue, and dysautonomia. It can also cause long-term stress responses, affecting the immune system, hormonal balance, and the body’s ability to recover from illness or exertion. There is a growing body of research that shows a link between trauma and chronic illness. People who have experienced significant emotional or psychological trauma may be more likely to develop CFS or experience a worsening of symptoms.
Studies have noted that the chronic activation of the stress response can create a vicious cycle in which the body remains in a heightened state of alertness, further depleting energy reserves and exacerbating fatigue. Emotional trauma may also influence the gut-brain axis, further compounding the physical and psychological challenges faced by those with CFS.
Symptoms Commonly Experienced in CFS
Fatigue
The hallmark symptom of CFS, it can be severe and persistent, and it doesn’t improve with rest. This fatigue is often disproportionate to the activity level and can last for 24 hours or more after even mild exertion.
Muscle and Joint Pain
Many people with CFS report widespread muscle pain, joint pain, and headaches, often without any overt signs of inflammation.
Cognitive Dysfunction
Brain fog, memory issues, trouble concentrating, and a sense of confusion are common. This is often referred to as “cognitive impairment” or “brain fog” and is one of the most disabling aspects of the condition.
Sleep Disturbances
Despite feeling chronically fatigued, many people with CFS have trouble falling or staying asleep, and they may wake up feeling unrefreshed.
Post-exertional Malaise (PEM)
A unique and debilitating symptom of CFS is post-exertional malaise, where symptoms worsen significantly after physical or mental exertion. This can lead to days or even weeks of debilitating symptoms following even mild activities.
Sensitivities
What is Chronis Fatigue Syndrome
Chronic Fatigue Syndrome is a multifaceted condition with complex underlying mechanisms. It is key in understanding CFS to appreciate the interplay between the immune system, metabolism, neurological function, emotional trauma, and environmental factors. Functional medicine approaches of treatment aim to address all of these interconnected factors and systems in order to direct those suffering with CFS towards healing and recovery.
If you or someone you know, has been suffering with CFS and would like any further advice please feel free to contact us here.
References
References:
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- Myhill, S., & Booth, S. (2013). Mitochondrial dysfunction in chronic fatigue syndrome. Journal of Clinical Pathology, 66(7), 580–586.
- Robinson, M., & Dobson, A. (2018). The autonomic nervous system and chronic fatigue syndrome. Clinical Autonomic Research, 28(4), 341–349.
- Yelland, L. M., & Avenell, A. (2019). Gut microbiome and its role in CFS/ME. Microorganisms, 7(10), 420.
- Ray, A., & Agrawal, A. (2020). The link between stress, trauma, and chronic illness. Journal of Psychosomatic Research, 133, 109–115.
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the literature.” Journal of Clinical Virology, 62, 99-104. - Mangan, A. M., et al. (2015). “Cytomegalovirus and its role in the pathophysiology of chronic fatigue syndrome.” Journal of Clinical Pathology, 68(5), 391-398.,
- Dowsett, E. G., et al. (1990). “Chronic enteroviral infection and myalgic encephalomyelitis.” Journal of Clinical Pathology, 43(1), 51-53.
- Krupp, L. B. (2003). “Chronic fatigue syndrome and Lyme disease: Clinical findings and pathophysiology.” Annals of Internal Medicine, 138(4), 312-320.
