Patients diagnosed with Fibromyalgia syndrome generally complain about physical as well as mental fatigue. With medical imaging technologies it could be proven that Fibromyalgia syndrome patients show abnormal changes in the central nervous system. The evaluation of the individual history of Fibromyalgia syndrome cases uncovered a high prevalence of stress related factors including anxiety, obsessive disorders and sleep disturbances.

So there is sufficient clinical evidence to state a direct connection between Fibromyalgia syndrome and fatigue. As a matter of fact debilitating fatigue is one of the criteria required for the final diagnosis of Fibromyalgia syndrome. This said, the exact relation between Fibromyalgia syndrome and fatigue still has to be established.

One theory about the causes of Fibromyalgia syndrome however claims that the inability to reach stage four sleep could be a triggering factor for Fibromyalgia syndrome. Stage four deep sleep is considered essential for maintaining regular functions of the nervous system, and electroencephalography studies have shown that Fibromyalgia syndrome patients lack slow-wave sleep. So following this theory an unknown cause would impede regular deep sleep, causing chronic fatigue and finally resulting in the picture of a fully developed Fibromyalgia syndrome.

Two completely different theories about the causes of Fibromyalgia syndrome formulate irregularities with dopamine and/or serotonin, both important neurotransmitters that influence addiction patterns, the pathology of schizophrenia and Parkinson’s disease (dopamine) and determine sleep patterns, mood, concentration and perception of pain (serotonin). Again it can be stated that also according to these theories fatigue – this time as a consequence of neurotransmitter dysfunctions – would be a central part of the Fibromyalgia syndrome.

Another, again completely different hypothesis postulates that Fibromyalgia syndrome is essentially a psychosomatic disorder which camouflages a deep depression as the underlying cause. Also in this case one can easily recognize chronic fatigue as an integral part of such a depression.

Though there have been several studies and research projects for all these theories, none of them so far have led to conclusive results.