ME/CFS includes debilitating fatigue that is constant or recurring. This is not tired because you’ve had a long day, it’s the kind of fatigue you experience when you have the flu or are undergoing chemotherapy. Some patients describe this as feeling like they have lead in their body or that they have no energy, like a dead battery.

But it also has other symptoms, such as waking up feeling drained or like you have a hangover. Most of these patients take more time (up to two hours) to transition from sleeping to awake activity. They may have insomnia or require more than eight hours of sleep, yet still not feel refreshed in the mornings.

ME/CFS also includes trouble with thinking abilities. This could include the inability to process new information quickly (such as when given driving directions or asked to remember a phone number). It could include the inability to do math’s in your head or difficulty multitasking. Forgetting words or getting your “wires crossed” is also commonly reported in those with ME/CFS.

Another symptom, orthostatic intolerance, may make a person uncomfortable standing in one place long. The patient feels a strong urge to lie down or they may feel dizzy. Often patients unconsciously compensate by folding their legs when they sit down or shifting their weight from one leg to another when they stand. They may not know why, but they avoid lines, doing dishes at a sink, or standing at a sink to brush their teeth. Standing in a hot shower exacerbates this feature of the disease.

Other symptoms some patients experience include muscle pain, sore throat, swollen lymph nodes, sound and light sensitivity, cold and heat sensitivity, headaches, easy bruising, and vertigo. In all, about 60 different symptoms can occur with the disease, and each patient’s symptom profile may be different.

How does it start?

The disease can be triggered by an infection or series of infections, surgery, another illness, an accident, or any other physical or emotional stressor. It may come on gradually or suddenly. Commonly, people with the disease say they feel they caught the flu, but it never went away. Some report the symptoms starting one day without any apparent trigger. ME/CFS seems to have a genetic component because it occurs more often among blood relatives.

What causes the symptoms?

Research has revealed brain inflammation, systemic inflammation, low blood volume, immune system deficiency, abnormal gene reactions to exercise, abnormal energy metabolism in response to exercise, and abnormalities in the hypothalamic/adrenal/pituitary system. But none of these biological findings has led to a widely accepted diagnostic marker or led to an understanding of the cause of all the symptoms.