Chronic Fatigue Syndrome

  • What is Chronic Fatigue Syndrome?

  • How common is Chronic Fatigue Syndrome?

  • What is the cause of Chronic Fatigue Syndrome?

  • How is the diagnosis of Chronic Fatigue Syndrome made?

  • Which factors can trigger Chronic Fatigue Syndrome?

  • Is Chronic Fatigue Syndrome a neuromuscular disease?

  • Is there organic evidence for Chronic Fatigue Syndrome?

  • What factors maintain or contribute to Chronic Fatigue Syndrome?

  • How others react and the advice they offer.

  • Since the cause of Chronic Fatigue Syndrome is not known, can it be treated?

  • References.


What is Chronic Fatigue Syndrome (CFS)?


Chronic Fatigue Syndrome (CFS) is also known as Myalgic Encephalomyelitis (ME), post-viral fatigue syndrome (PVFS) and recently it was named as "Systemic Exertion Intolerance Disease” (SEID) [1]. The fact that a number of names have been given to CFS is an indication of the different theories that exist around it. The term CFS was given by American scientists as it was found to describe the condition shortly, clearly and without making assumptions about its causes.

The main problem affecting people with CFS is persistent fatigue, and this is not like the usual tiredness that any person can feel. In CFS fatigue is usually severe and it causes difficulties in the daily life of the individual by affecting their physical and mental functioning. A number of other symptoms exist and they include muscle pain, joints pain, headaches, painful lymph nodes, possible problems with orthostasis, sleep problems, memory problems, difficulty in finding words and processing information, and other.

Fatigue and the other symptoms may be present at rest and worsen even with little physical or mental effort. Activities of daily living such as shopping, housework, writing, maintaining a discussion can be tedious and require great effort to be made. People with chronic fatigue often live a life with limited activities and in some severe cases, may become wheelchair bound or bedridden. As a result, there may be irritability, low mood, anxiety and possible depression.


How common is Chronic Fatigue Syndrome (CFS)?


CFS is a relatively common disease. It is estimated that 0.8% of the population have it [2] and half of the patients need therapeutic support from specialised centres [3]. In Greece there are not, yet, epidemiological studies on the prevalence of CFS and the information on the other kinds of fatigue is very limited. Assuming that the same or similar epidemiological data may apply to Greece, only patients with CFS can be several thousands with half of them being in need for help from specialist therapists. These figures grow if the studies showing CFS to have a percentage as high as 3% are taken into account. The rates increase a lot if fatigue that follows other chronic diseases is taken into account. For example, chronic fatigue after a stroke may be up to 70% [4.5].


What is the cause of Chronic Fatigue Syndrome (CFS)?


The cause of CFS is not yet known. Probably not a single cause will be found to exist for this complex condition. Factors that may trigger the syndrome can be a viral disease, psychosocial stressors, overactive life, or decreased physical activity. Lately, there are more studies being conducted on the causes of CFS and the contribution of biomarkers. Many scientists consider CFS to be a multifactorial syndrome and not the process of a single disease. This will not be unique in CFS as it is known to happen in other health conditions like, for example, heart disease where many factors contribute to its appearance.


How is the diagnosis of Chronic Fatigue Syndrome (CFS) made?


The diagnostic criteria and the necessary tests to be carried out for the diagnosis of CFS, as they are defined by our knowledge so far, are described here.


Which factors can trigger Chronic Fatigue Syndrome (CFS)?


Viral infection

Many people with CFS report a viral infection or recurrent infections such as flu, cold, diarrhoea and vomiting or a glandular fever. During their illness they have more symptoms including pain and fatigue. As a result, people rest which is needed in order to feel better. This is followed by a gradual recovery, but there are cases when the symptoms persist.


Symptoms can persist for different reasons. Prolonged stress or ill health that can be pre-existing to the disease, can lead to prolonged time needed to recover from the disease. The immune system can be affected by stress and if this is present before, during or after the start of the illness then it could delay the recovery. Another factor that can delay recovery is depression. Weakness and fatigue occurs in all individuals after a long period of fatigue and prolonged rest. When very active people have an illness (e.g. athletes) they could decondition fast and more fatigue can develop as a result.


Many people do many things, very quickly, such as go back to exercising too soon or exercising too much without taking a lot of breaks during the acute stage of the disease, which lead to prolonged fatigue. This often occurs in people who expect to recover quickly, are not aware of the characteristics of the illness, who were used to be active or who do not like being unhealthy. Other risk factors are high personal expectations and social or work pressure.

When recovery is slower than usual it does not mean that the acute phase of the illness is still taking place, but there could be prolonged fatigue and intolerance to activities and exercises. This usually happens after a prolonged illness. The person feels as if they have the viral disease, but it does not exist. In CFS there is no infection anymore. When the acute phase of the infection has passed then the virus leaves.

Other factors that can trigger CFS

CFS is not always associated with a viral disease. It can be triggered by a bacterial infection (such as brucellosis or hepatitis), after a pregnancy, after traumatic events (such as the sudden loss of a loved one), after overactive life and extreme anxiety, but it could also appear suddenly without any apparent reason.


Is CFS a neuromuscular disease?


CFS is not a disease of the muscles. Studies have shown that muscles work properly, although patients may not feel they do. The present muscle pain does not actually cause a permanent damage. In CFS, simple activities can initiate a process similar to that of inactive muscles, which face unexpected requirements. In such cases, the muscles present uncoordinated contractions, which are painful and inefficient. Often, there may be potential muscle damage and delayed onset of muscle pain.


Is there organic evidence for Chronic Fatigue Syndrome (CFS)?


The exact physiological mechanism around CFS remains unclear. It could be that there are physiological mechanisms but they are not yet understood and confirmed scientifically. There is evidence of changes in the immune system and some suggestions of changes in the operation of the hypothalamus and the cortisol production. Investigations into the causes and treatments of CFS are ongoing, but still there is little evidence surrounding the organic evidence of the occurrence of the syndrome. Whatever triggers the syndrome, the presence of a biochemical dysfunction may be an important reason why patients begin to feel very tired. When fatigue and disability settle, then other factors may intervene and affect the experience of CFS.


What factors may maintain or contribute to Chronic Fatigue Syndrome (CFS)?


Activity and rest during CFS

Most patients try to overcome their unexpected, prolonged and severe fatigue by rest or by pushing themselves to go back to their normal activities. Others do both. While these are normal ways of coping and possibly the only ones that the patients can do, they can result in perpetuating the vicious cycle of symptoms and disability.

Patients face increasingly intense fatigue and pain, and their natural reaction is to rest more and significantly reduce the activities of daily life. While rest soothes the symptoms in the short term, in the long term it causes problems with reduced exercise tolerance and muscle weakness. There may be loss of muscle mass, problems with the circulatory and respiratory system and increased sensitivity to activity. As a result, some people may become more sensitive to repeated experiences of exhaustion, pain and failure on efforts for activity and wish to avoid or reduce such experiences. To avoid these experiences, as the symptoms are translated as signs to reduce their activities, they limit further their functions.

Some people try to manage their condition by fighting through it, often ignoring the fatigue. This does not last long since they end up feeling exhausted. Often people find that since neither resting more nor doing more helps them, they end up doing what they can when they can. This pattern of increase - decrease (boom - bust) of the activity results in fatigue and perpetuates a plateau phase instead of improving activity.


Emotional impact

CFS can have a severe impact on the emotions of the person living with this illness, but often these emotions are not understood. Anxiety, depression, frustration, boredom can occur in chronic conditions and can perpetuate fatigue. We know that depression and anxiety cause physiological changes, which include increased fatigue, muscle pain, memory and concentration problems and decreased motivation and activity. People with CFS often have fear of making things worse and are worried about their unknown illness. Past experiences where symptoms became worse, result in the creation of fear of the disease, but also of the activities. Frustration is often inevitable because of the constraints the individual has due to the syndrome, but also because of the high expectations that often the patients have of themselves. This may, too,  have an effect on reducing activities.


How others react and the advice they offer

It is not usual that people are given the correct advice and this affects their situation negatively. Some people are not given any advice at all or they are told to follow a life of limitations, while others receive mixed advice as to remain in bed for a month or go for a quick run. Not offering specialist professional advice often leads to the chronicity of the disease and increases the suffering from it.

Receiving wrong advice by others, especially from those who do not consider people with CFS as patients or do not take their symptoms seriously, can result in anxiety. It could be that health professionals do not consider the disease as a real disease because the lab tests are unclear, it could be because patients may look healthy and have few physical symptoms. For these reasons, patients may be accused of hypocrisy or even hysteria. Often patients are told that they only suffer from depression. Although depression may be present in some cases, it is not the complete story. Frequently, patients are told that all this illness is simply in their minds.

Family, friends and health care providers' support is essential. Sometimes, it can be difficult for others to understand what is happening, especially when the symptoms are not many or when they only see the patient on the days they feel better. Sometimes, social attitudes toward chronic diseases tend to see the condition as normal/real or psychological/"in the mind" of the individual. This is a misconception because all diseases are a mix of physiological and psychological factors.


Since the cause of Chronic Fatigue Syndrome (CFS) is not known, can it be treated?


Although the causes of CFS are not clear, this does not mean that it cannot be treated. There are several other conditions where their causes are not clear, for example high blood pressure, seizures and others, or where the original cause does not exist anymore, for example chronic back pain after an injury and phantom limb pain after amputation. However, these diseases are often treated successfully not by addressing the primary cause, but by identifying and treating the triggers and the symptoms. In general, in chronic conditions the initial episode that caused the illness may be different from the factors that keep it over time.


Studies show that most of people with CFS gradually improve over time. However, the rate and speed of recovery increase significantly with proper treatment. There is no known pharmacological treatment or cure for CFS. However, the symptoms should be managed with standard clinical practice. The National Institute for Health and Care Excellence of the United Kingdom recommends two types of treatment for CFS, Graded Exercise Therapy (GET) and Cognitive Behavioural Therapy (CBT) [5].




  1. Clayton et al. Beyond Myalgic Engephalomyelitis / Chronic Fatigue Syndrome. Redefining and illness. Report guide for clinicians. The National Academy Press 2015 Washington D.C.

  2. Johnston et al. The prevalence of chronic fatigue syndrome/myalgic encephalomyelitis: a meta-analysis. Clinical Epidemiology 2013;5:105–110.

  3. NICE, Clinical Guideline 53. Chronic fatigue syndrome/myalgic encephalomyelitis (or encephalopathy). Diagnosis and management of CFS/ME in adults and children, 2007.

  4. Glader et al. Poststroke Fatigue A 2-Year Follow-Up Study of Stroke Patients in Sweden. Stroke, 2002;33:1327-1333.

  5. May et al. Improved physical fitness of cancer survivors: A randomised controlled trial comparing physical training with physical and cognitive-behavioural training. Acta Oncologica, 2008;47(5):825-834