In the most common type of fibromyalgia, the causes are not known. Physical injuries, emotional trauma, or viral infections such as Epstein-Barr may trigger the disorder, but no one trigger has proven to be a cause of primary fibromyalgia.
Many experts believe that fibromyalgia is not a disease, but is rather a chronic pain condition brought on by several abnormal body responses to stress. Areas in the brain that are responsible for the sensation of pain react differently in fibromyalgia patients than the same areas in healthy people.
People with fibromyalgia have decreased activity in opioid receptors in parts of the brain that affect mood and the emotional aspect of pain. This reduced response might explain why fibromyalgia patients are likely to have depression, and are less responsive to opioid painkillers, researchers say.
Chronic Sleep Disturbance
Sleep disturbances are common in fibromyalgia. Patients with the condition have a higher-than-average rate of a sleep disorder called periodic limb movement disorder (PLMD). Patients with PLMD involuntarily contract their leg muscles every 20 - 40 seconds during sleep, which may occasionally wake them up.
It is not clear whether fibromyalgia leads to poor sleeping patterns, or the sleep disturbances come first. Researchers continue to investigate the link between fibromyalgia and sleep.
- Patients with fibromyalgia have increased rates of cyclic alternating sleep pattern (CAP), which may produce serious sleep problems and have been strongly linked to symptom severity. CAP may be related to PLMD.
- Sleep disorders that cause breathing problems are common in women with fibromyalgia.
- Other biological measures of troubled sleep, such as levels of the hormone melatonin (which helps regulate circadian rhythms and the sleep-wake cycle), appear to be normal in most people with fibromyalgia.
Review Date: 12/27/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.