Chronic fatigue syndrome (ME/CFS) experts assert two symptoms; post-exertional malaise” and cognitive  problems, are the hallmark symptoms of this disorder.


man lying down

Exhaustion induced by small amounts of exertion is typical in chronic fatigue syndrome

People with chronic fatigue syndrome (ME/CFS) experience unusual levels of fatigue or exhaustion after mild exertion. The Centers For Disease Control  (CDC) calls the fatigue ‘severe, incapacitating, and all-encompassing” At its most severe ME/CFS leaves people with chronic fatigue syndrome house or bed-bound.

Post-exertional malaise  (PEM) – The term ‘post-exertional malaise’ (PEM) was coined in an attempt to describe a unique kind of fatigue present in ME/CFS.  It refers to symptom flareups after physical or mental exertion that can last for days to weeks. Exercise tests suggest many people with ME/CFS have a unique metabolic deficit that prevents them from regularly engaging in much physical activity.

A study which identified five different types of fatigue in ME/CFS, only one of which was found in the healthy population, suggested unique types of fatigue are present in the disease.

  • ‘Post-exertional fatigue (or malaise)’ –  occurs after physical or mental exertion; it is considered a hallmark symptom of this disease.
  • ‘Brain fog’ – involves having difficulty with words and concentration; it is considered a hallmark symptom of this disease.
  • ‘Wired But Tired fatigue’ – characterized by low energy levels accompanied by a feeling of over stimulation or being unable to relax, feeling ‘wired and tired’ is common in chronic fatigue syndrome.
  • Molasses Fatigue’ – is characterized by a feeling of heaviness in the limbs.
  •  Flu-like fatigue – similar to what people who have a cold experience.

Other Symptoms

Problems Getting a Good Nights Sleep

Almost all chronic fatigue syndrome (ME/CFS) patients experience unrefreshing sleep and/or reduced or increased levels of sleep. Sleep issues can range from insomnia, to early waking, to difficulty achieving deep sleep. Sleep studies focusing on traditional sleep issues have had mostly unremarkable findings but recent studies employing measures of autonomic nervous functioning suggest that system is intimately involved in sleep and other issues.

Difficulty ‘Thinking’

People with ME/CFS  often report more difficulty with thinking including slowed understanding, trouble finding or saying words, trouble with writing, reading and mathematics, inability to keep track of things, short term memory problems and poor concentration.  Studies indicate that problems with ‘executive functioning’ (working memory, planning, organizing) are particularly affected.

Autonomic Nervous System Symptoms

Many autonomic nervous system symptoms are found including difficulty standing (orthostatic intolerance), rapid heartbeat and poor blood pressure regulation (particularly during standing) that causes  dizziness, nausea, fatigue, headaches, sweating, pallor, mottling in lower limbs, etc.;  palpitations, breathing dysregulation (breath holding, irregular breathing, exercise induced shortness of breath), irritable bowel syndrome (constipation, diarrhea, cramping, bloating and/or nausea), visual disturbances, burning sensations, chest pain…

woman in pain

Many of the defining symptoms of ME/CFS are pain symptoms. Upper body pain is particularly common.


Widespread muscle and joint pain,  tension headaches and shoulder and neck pain are common.  Migraines without aura are common. Upper body pain is particularly common. Studies indicate that lower pain thresholds, particularly after exercise, are present and allodynia can be found.

Sensory ‘Overload ‘

Hypersensitivity to light, sound, odors, vibration, speed, reduced multi-tasking ability, difficulty making decisions, motor overload – increased clumsiness, etc. when fatigued, dizziness, numbness, tingling, nausea are often found.

Visual Tracking

Vertigo, loss of depth perception, inability to follow quickly moving objects, etc. are common.

Muscle Coordination

Poor coordination, effortful movement, difficulty with everyday activities such as brushing one’s teeth, dialing the telephone, etc.

Hormonal Type Symptoms

Increased or reduced body temperature, hot/cold feelings, intolerance of weather extremes, feverishness, sweating episodes, weight gain or weight loss, anxiety or panic attacks, alcohol intolerance often occur. Studies suggest gynecological issues are common in ME/CFS.

Immune System Symptoms

Sore throat, tender lymph nodes, fever, muscle and joint pains, new sensitivities to food, drugs and/or chemicals are common. Once thought to be a hallmark of this disorder, studies have indicate that enlarged lymph nodes are not common.

Mood Issues

Irritability, depression and/or anxiety commonly occur in chronic diseases and  are increased in ME/CFS as well.  Mood disorders are not increased in people with ME/CFS before they become sick.

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