The main symptom of fibromyalgia is pain that is believed to derive from an increased sensitivity to pain stimuli. The pain can be brought on by different situations, including noises, weather changes, or stress, but it may also occur without any relation to external events. The characteristic pain usually affects the neck, buttocks, shoulders, arms, upper back, and chest. "Tender points" are localized areas of the body that are tender to light touch. The tender points of fibromyalgia are commonly located around the elbows, shoulders, knees, hips, back of the head, and the sides of the breastbone. Other common symptoms associated with fibromyalgia include fatigue, sleep disturbances, migraine, numbness or tingling in various body parts, and irritable bladder. Irritable bladder can cause frequent urination and discomfort during urination (dysuria). Bowel disturbances as seen with irritable bowel syndrome may occur, including diarrhea and abdominal pain. Irritability, mood changes, depression, forgetfulness, and anxiety are emotional symptoms of fibromyalgia.