Fibromyalgia (FM) is a chronic illness that causes pain in muscles and ligaments. In addition to muscular pain and stiffness, this medical condition also causes fatigue, sleep problems, depression, and an inability to think clearly. FM affects about 4 million Americans, the vast majority of them are women in their mid-30s to late-50s. Once classified as a psychological disorder, due to the lack of objective findings on physical exams, blood tests or x-rays, FM has recently been reclassified as a central sensitivity syndrome (CSS).