Journal of Sleep Medicine & Disorders Cite this article: Fatima G, Das SK (2016) Deciphering the Role of Sleep in Fibromyalgia Syndrome. J Sleep Med Disord 3(4): 1055. Central *Corresponding author G hiza l Fa tim a , De p a rtm e nt o f Rhe um a to lo g y, K.G . Me d ic a l Unive rsity, Luc kno w , Ind ia , Em a il: Submitte d: 03 Fe b rua ry 2016 Accepted: 30 Ma y 2016 Publishe d: 31 Ma y 2016 ISSN: 2379-0822 Copyright © 2016 Fa tima e t a l. OPEN ACCESS Ke ywo rds • Sle e p • Fib ro m ya lg ia • Dysm e no rrho e a • Hyp e ra lg e sia Review Article Deciphering the Role of Sleep in Fibromyalgia Syndrome Ghizal Fatima* and Siddharth Kumar Das Department of Rheumatology, K.G. Medical University, India Abstract 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 diffcult 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. INTRODUCTION FMS is a chronic musculoskeletal pain disorder of unknown aetiology, characterised by chronic widespread pain and muscle tenderness and the presence of tender points on examination. Patients experience both allodynia (pain from a normally non- painful stimulus) and hyperalgesia (inappropriately intense pain from a normally painful stimulus). Other common accompanying features are fatigue, sleep disturbances, stiffness, and paraesthesias, headaches, Raynaud’s like symptoms, depression and anxiety [1]. FMS is much more than widespread pain as it overlaps substantially with other central sensitivity syndromes such as chronic fatigue syndrome, irritable bowel syndrome, chronic pelvic pain syndrome/ primary dysmenorrhoea; temporo- mandibular joint pain, multiple chemical sensitivity, restless legs syndrome and interstitial cystitis. The diagnostic criteria have changed repeatedly, and there is neither a definitive pathogenesis nor reliable diagnostic or prognostic biomarkers. Clinical and laboratory studies have provided evidence of altered central pain pathways. Few patients with FMS also report difficulty with swallowing, bowel and bladder abnormalities, numbness, tingling and cognitive dysfunction [2]. FMS is a persistent and potentially debilitating disorder that can have a devastating effect on quality of life, impairing the patient’s ability to work and participate in everyday activities, as well as affecting relationships with family, friends, and employers. It imposes heavy economic burdens on society as well as on the patient [3]. There is as yet no cure for FMS. Some treatments have been shown by controlled clinical trials to effectively reduce symptoms, including medications, behavioral interventions, patient education, and exercise. FMS is one of the least understood pain syndrome in medicine today, which is a chronic disorder characterized by persistent and widespread pain, with an estimated prevalence of 2-4% in the adult general population [3.4% for women and 0.5% for men] [4]. FMS definition and content has changed repeatedly in the 110 years of its existence. The most important change was the requirement for multiple tender points and extensive pain for diagnosis of this condition that arose in the 1980s (1990 American College of Rheumatology classification criteria) [5]. In 2010, a second shift revised the definition of FMS, so it came into being in the form of the preliminary 2010 ACR criteria that excluded tender points,