Deciphering the Role of Sleep in Fibromyalgia Syndrome

Fibromyalgia syndromes (FMS) is a chronic and debilitating musculoskeletal pain disorder of unknown aetiology with usual accompanying features of fatigue, sleep disturbances and stiffness and is one of the least understood pain syndrome in medicine today. Other symptoms include tingling of the skin, prolonged muscle spasms, weakness in the limbs, nerve pain, muscle twitching and chronic sleep disturbances. In addition to this FMS is perceived as a disorder of central sensitization. Polysomnography data has demonstrated that FMS patients have reduced short-wave sleep suggestive of wakefulness during non-REM (rapid eye movement) sleep. In FMS, the combination of pain and sleep disturbance is a double-edged sword: the pain makes sleep more difficult and sleep deprivation exacerbates pain and the reduction in sleep disturbance is usually followed by improvement in pain symptoms. Sleep disturbances are among the most common symptoms of FMS, a chronic condition affecting the spinal cord and brain that causes patient to feel pain and fatigue, and affects concentration. In fact, along with the tiredness, pain, and psychosocial distress, sleep disturbances are a core feature in FMS patient. In the last few years, it has become increasingly clear that treating the associated sleep disturbance improves the daytime symptoms of FMS. Mechanistically, sleep deprivation impairs descending pain-inhibition pathways that are important in controlling and coping with pain. Clinical trials of pharmacological and non-pharmacological therapies have shown that improving sleep quality can reduce pain and fatigue, further supporting the hypothesis that sleep dysfunction is a pathogenic stimulus of FMS. Therefore, it is important to understand the sleep disturbances in FMS patients. In this review we will try to elucidate the sleep abnormalities in FMS patients.