Causes
Fibromyalgia is grouped into two categories:
- Primary (idiopathic) fibromyalgia -- the causes are not known
- Secondary fibromyalgia -- the causes can be identified
Primary fibromylagia is the most common type. Many experts believe that fibromyalgia is not a disease but rather a chronic pain condition brought on by a number of abnormal body responses to stress. Physical injuries, emotional trauma, or viral infections such as Epstein-Barr may act as triggers for the onset of the disorder, but none have proven to be a cause of primary fibromyalgia.
Chronic Sleep Disturbance
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Sleep disturbances are common in fibromyalgia. Both adult and young patients with fibromyalgia have a higher than average rate of a sleep disorder called periodic limb movement disorder (PLMD). PLMD used to be called nocturnal myoclonus. Patients with PLMD involuntarily contract their leg muscles every 20 to 40 seconds during sleep. This may occasionally wake up the patient.
Some experts believe that fibromyalgia does not lead to poor sleeping patterns, but that sleep disturbances come first. Researchers continue to investigate the link between fibromyalgia and sleep.
- In one study, healthy volunteers reported fibromyalgia-like pain after they had been subjected to disrupted deep sleep. Disturbed sleep appears to trigger factors in the immune system that cause inflammation, pain, fatigue, and lower tolerance to pain. A 2004 study published in the journal Rheumatology found that patients with fibromylagia have increased rates of the cyclic alternating sleep pattern (CAP). The increase CAP produced significant sleep impairment, which was strongly linked to symptom severity. (Previous studies have also suggested that CAP may be related to PLMD.)
- A 2004 report published in the journal Sleep found that sleep-disordered breathing is common in women with fibromyalgia.
- Other biologic measures of troubled sleep, however, such as levels of the hormone melatonin, which helps to regulate circadian rhythms and the sleep-wake cycle, appear to be normal in most fibromyalgia sufferers.
Brain Chemicals and Hormonal Abnormalities
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