What Causes Fibromyalgia?

Piecing it Together

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When you have a debilitating illness that impacts all aspects of your life, it's normal to ask "why?" When it comes to fibromyalgia (FMS), we're constantly adding more and more pieces to the puzzle. While we don't yet have a complete picture, we're getting closer.

Experts are learning a lot about what leads to FMS, but they're still not clear on why these things lead to FMS in some and not in others.

Many experts believe the condition is linked to a genetic predisposition, which could clear up that question.


Fibromyalgia is grouped into two categories: primary and secondary. Primary FMS is the most common and is also called "idiopathic" FMS, meaning it has an unknown cause. Secondary FMS is associated with other causes of chronic pain.

#1 - Primary (Idiopathic) Fibromyalgia

Suspected causes of primary FMS include abnormalities in the brain and hormones, chronic sleep disturbance, psychological and social effects, and muscle abnormalities. Research is also looking in multiple other directions, with varied success.

Brain & Hormonal Abnormalities

Studies show, with FMS, the parts of your central nervous system that deal with pain signals work differently from other people's. This is called central sensitization.

Researchers know people with FMS can have numerous abnormalities in their hormonal, metabolic and brain-chemical activity, but they're not sure whether these are causes of fibromyalgia or the effect of pain and stress on the central nervous system.

Some physical changes in the brain have been discovered, as well.

People with FMS may have abnormalities in any of the following:

  • Melatonin: low levels
    Some studies show taking melatonin supplements can cut pain levels, improve sleep and help alleviate depression symptoms in people with FMS. However, other studies have shown little or no improvement.
  • Norepinephrine & Dopamine: low levels
    Low levels of norepinephrine can lead to loss of alertness, mental fog, depression, and apathy. Your body uses norepinephrine to create dopamine, and low dopamine results in muscle pain, further cognitive dysfunction, and movement-related problems (i.e., tremor, poor balance, clumsiness.)
  • Glutamate & GABA: out of balance
    Glutamate's job is to get your brain cells riled up. It's important for learning and other situations that require rapid thought. GABA's job is to counter glutamate and calm your brain. In FMS, research shows that glutamate levels are too high in relation to GABA, which can lead to overstimulation and even death of brain cells.
  • Stress hormones: low levels
    Deficiencies in the stress hormones cortisol and norepinephrine make your body less able to cope with psychological or physical stress. (Physical stress includes infection or strenuous activity.)
  • IGF-1 growth hormone: low levels
    This hormone promotes bone and muscle growth. Low levels are related to problems with thinking, low energy, muscle weakness an intolerance to cold. This level may be a marker of FMS rather than a cause.
  • Substance P: high levels
    Substance P is a chemical messenger in the nervous system associated with pain perception. If you have too much, your brain gets too many pain signals. People with FMS can have up to three times the normal amount in their spinal fluid.
  • Abnormal pain perception: high activity levels
    Some studies and brain scans suggest fibromyalgia patients have too much activity in the parts of the brain and central nervous system that process pain.

Researchers are working to understand what these abnormalities mean and how this knowledge can lead to treatments.

Chronic Sleep Disturbance

Sleep disturbances and fibromyalgia go hand and hand, and some experts believe sleep disturbances come first. People with FMS have higher than average rates of restless leg syndrome, periodic limb movement disorder (PLMD) and sleep-related breathing disorders such as sleep apnea.

Some sleep problems of FMS may be linked to levels of the nervous-system chemicals serotonin and melatonin, which help regulate sleep-and-waking cycles.

Psychological & Social Effecs

According to studies, people with FMS are more likely than others to have experienced severe emotional and physical abuse. This suggests that post-traumatic stress disorder (PTSD) or chronic stress could play a strong role in the development of FMS in some people.

Evidence shows that stress and PTSD actually lead to changes in the brain, possibly from long-term over-exposure to stress hormones.

Muscle Abnormalities

Though these things cannot be tested at your doctor's office or clinic, some research has shown that people with FMS have three kinds of muscle abnormalities:

  • Biochemical
    Some FMS patients have low levels of muscle-cell chemicals that make sure you have enough calcium in your muscles. When levels are low, the muscles stay contracted rather than relaxing.
  • Structural & blood flow
    Researchers have found people with FMS have especially thick capillaries (tiny blood vessels). This could mean your muscles don't get enough oxygen-rich blood or other compounds you need for proper muscle function.
  • Functional
    Experts don't know why this is but speculate that the pain and stress of the disease itself may harm muscle function.

#2 - Secondary Fibromyalgia

Secondary fibromyalgia appears either after or in conjunction with other medical problems, usually one of the following:

When there's another condition at work, it can give doctors a real a challenge when it comes to diagnosing secondary FMS. First, it can be difficult to sort out what condition is causing what symptoms. Second, FMS is considered a diagnosis of exclusion because anything reversible has to be treated before a doctor can diagnose it.

If you suspect you have FMS on top of another condition, talk to your doctor. Good communication is often the key to a successful diagnosis.


de Zanette SA, et al. BMC pharmacology & toxicology. 2014 Jul 23;15:40. Melatonin analgesia is associated with improvement of the descending endogenous pain-modulating system in fibromyalgia: a phase II, randomized, double-dummy, controlled trial.

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