In order to communicate with one another, the two branches of the autonomic nervous system use special chemical hormones, called neurotransmitters. Neurotransmitters act as vehicles, carrying information back and forth between your brain and your body.

If something goes wrong with these neurotransmitters, messages from the body to the autonomic nervous system can easily be confused.

Specific neurotransmitters that are thought to play a role in fibromyalgia:

  • Substance P: Substance P is a neurotransmitter found in your spinal fluid. It helps to communicate sensations of pain to your brain and body. A number of studies have shown that fibromyalgia patients have up to three times more Substance P in their spinal fluid than healthy people. This can cause enhanced perceptions of pain, making a normally mild stimulus excruciatingly painful.
  • Endorphins: Endorphins are hormones secreted by the body in reaction to physical stress, such as exercise or fear. Endorphins are considered a natural opioid and help your body to deal with pain and fatigue. Beta-endorphin is highly involved in pain suppression, but fibromyalgia patients appear to have only 50% of the normal levels of this endorphin. This could explain why fibromyalgia patients experience so much pain.
  • Serotonin: Serotonin is a neurotransmitter that helps to regulate your mood. It keeps you from feeling overly depressed or manically excited. A number of studies have reported that fibromyalgia patients appear to have low levels of serotonin in their brains. Low levels of serotonin have been linked with depression, anxiety, and chronic headaches. Antidepressants that manipulate the levels of serotonin in the brain seem to alleviate these fibromyalgia symptoms.


Along with neurotransmitters, your autonomic nervous system also relies on hormones in order to stimulate certain bodily functions. Hormones are special chemicals secreted by various glands in your body, helping to trigger growth, fertility, and other functions.

Hormones that are important to your autonomic nervous system include:

  • Cortisol: The hormone cortisol is secreted by your adrenal glands. It is released when your body is physically threatened or stressed. Commonly referred to as the "stress hormone," cortisol function tends to be abnormal in fibromyalgia patients. If you have fibromyalgia, your body often considers itself to be in a stressed state. As a result, you release more cortisol than most people. This can you leave you feeling persistently tired and drained. 
  • Growth Hormone: Growth hormone is released during exercise and deep sleep and helps to control muscle and tissue growth as well as metabolism. It helps to heal wounds and injuries incurred by your body throughout the day. People with fibromyalgia appear to have very low levels of growth hormone is their bodies. For some reason, the autonomic nervous system doesn’t trigger the release of enough growth hormone to help repair muscles and tissues. To compound this, many fibromyalgia patients don’t get enough deep sleep, which limits the release of growth hormone. 
  • Norepinephrine Norepinephrine is a hormone released by your adrenal gland and controlled by your sympathetic nervous system. It helps to control stress responses, such as sweating, increased heart rate, and muscle contraction. Fibromyalgia suffers appear to have lower levels of epinephrine, contributing to pain and fatigue.


Table of Contents
1. System Dysfunction
2. Hormones out of whack?
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