Investigators are constantly looking at various explanations for the occurrence of fibromyalgia. Some, for example, are exploring hormonal disturbances and chemical imbalances that affect nerve signaling. Other experts believe fibromyalgia with its deep muscle pain is linked to stress, illness, or trauma. Still others think there is a hereditary cause or say there is no explanation at all. But while there is no clear consensus about what causes fibromyalgia, most researchers believe fibromyalgia results not from a single event but from a combination of many physical and emotional stressors.

Other Theories About Causes of Fibromyalgia

Some have speculated that lower levels of a brain neurotransmitter called serotonin leads to lowered pain thresholds or an increased sensitivity to pain. It’s associated with a calming, anxiety-reducing reaction. The lowered pain thresholds in fibromyalgia patients may be caused by the reduced effectiveness of the body’s natural endorphin painkillers and the increased presence of a chemical called “substance P.” Substance P amplifies pain signals.

There have been some studies that link fibromyalgia to sudden trauma to the brain and spinal cord. Keep in mind, though, theories about what causes fibromyalgia are merely speculative.

Who Gets Fibromyalgia?

Fibromyalgia is far more common in women than in men. Some interesting studies show that women have approximately seven times less serotonin in the brain. That may explain why fibromyalgia syndrome, or FMS, is more common in women.

Another theory states that fibromyalgia is caused by biochemical changes in the body and may be related to hormonal changes or menopause. In addition, some (but not all) people with fibromyalgia have low levels of human growth hormone, which may contribute to the muscle pain.

Symptoms of fibromyalgia include:

• Chronic muscle pain, muscle spasms or tightness
• Moderate or severe fatigue and decreased energy
• Insomnia or waking up feeling just as tired as when you went to sleep
• Stiffness upon waking or after staying in one position for too long
• Difficulty remembering, concentrating, and performing simple mental tasks (“fibro fog”)
• Abdominal pain, bloating, nausea, and constipation alternating with diarrhea (irritable bowel syndrome)
• Tension or migraine headaches
• Sensitivity to one or more of the following: odors, noise, bright lights, medications, certain foods, and cold
• Feeling anxious or depressed
• Numbness or tingling in the face, arms, hands, legs, or feet
• Increase in urinary urgency or frequency (irritable bladder)
• Reduced tolerance for exercise and muscle pain after exercise
• A feeling of swelling (without actual swelling) in the hands and feet

Fibromyalgia symptoms may intensify depending on the time of day — morning, late afternoon, and evening tend to be the worst times. Symptoms may also get worse with fatigue, tension, inactivity, changes in the weather, cold or drafty conditions, overexertion, hormonal fluctuations (such as just before your period or during menopause), stress, depression, or other emotional factors.