What causes fibromyalgia?

The cause of fibromyalgia is not known. Patients experience pain in response to stimuli that are normally not perceived as painful. Researchers have found elevated levels of a nerve chemical signal, called substance P, and nerve growth factor in the spinal fluid of fibromyalgia patients. The brain nerve chemical serotonin is also relatively low in patients with fibromyalgia. Studies of pain in fibromyalgia have suggested that the central nervous system (brain) may be somehow supersensitive. Scientists note that there seems to be a diffuse disturbance of pain perception in patients with fibromyalgia.

Also, patients with fibromyalgia have impaired non-Rapid-Eye-Movement, or non-REM, sleep phase (which likely explains the common feature of waking up fatigued and unrefreshed in these patients). The onset of fibromyalgia has been associated with psychological distress, trauma, and infection.