Why does it hurt?

Researchers believe repeated nerve stimulation causes the brains of people with fibromyalgia to change. This change involves an abnormal increase in levels of certain chemicals in the brain that signal pain (neurotransmitters). In addition, the brain's pain receptors seem to develop a sort of memory of the pain and become more sensitive, meaning they can overreact to pain signals.

Can it be treated?

While there is no cure for fibromyalgia, a variety of medications can help control pain and other symptoms. Exercise, relaxation and stress-reduction measures also may help.

Feb. 21, 2014 See more In-depth