It affects more females than males, with a ratio of 9:1 by American College of Rheumatology (ACR) criteria. Fibromyalgia is seen in about 2% of the general population. It is most commonly diagnosed in individuals between the ages of 20 and 50, though onset can occur in childhood.
The defining symptoms of fibromyalgia are chronic, widespread pain and tenderness to light touch. There is also typically moderate to severe fatigue. Those affected may also experience heightened sensitivity of the skin (also called allodynia), tingling of the skin (often needle-like), achiness in the muscle tissues, prolonged muscle spasms, weakness in the limbs, and nerve pain. Chronic sleep disturbances are also characteristic of fibromyalgia. Studies suggest that sleep disturbances are related to a phenomenon called, alpha-delta sleep, a condition in which deep sleep is frequently interrupted by bursts of brain activity similar to wakefulness. Deeper stages of sleep are often dramatically reduced.
Symptoms can have a slow onset, and many patients have mild symptoms beginning in childhood, that are often misdiagnosed as growing pains. Symptoms are often aggravated by unrelated illness or changes in the weather. They can become more tolerable of less tolerable throughout daily or yearly cycles; however, many people with fibromyalgia find that, at least some of the time, the condition prevents them from performing normal activities such as driving a car or walking up stairs. The disorder does not cause inflammation as is characteristic of rheumatoid arthritis, although some NSAIDs may temporarily reduce pain symptoms in some patients. Their use, however, is limited, and often of little to no value in pain management.