Melatonin levels in premenopausal women with fibromyalgia syndrome.

The fibromyalgia syndrome (FMS) is a chronic, widespread pain disorder of unknown etiology. It has been suggest that familial component, environmental factors, endocrine and neurotransmitter alterations, and psychological factors may contribute to the development of FMS. The role of melatonin in FMS is unclear. Some studies describe a lower nocturnal peak and a decreased secretion of melatonin in women with FMS when compared with healthy matched controls. The aim of the present study was to determine the possible role of melatonin in FMS patients. We examined the characteristics and levels of melatonin in 25 consecutive premenopausal women with FMS. Serum blood samples were collected from 25 patients and 20 the age and gender matched healthy controls. Melatonin levels were measured by enzyme-linked immunosorbent assay. Then, the results were compared with those from healthy subjects. Serum melatonin levels of FMS patients were not statistically different from those of controls (P > 0.05). No association was observed between melatonin levels of patients with FMS and disease duration, sleep disturbances, fatigue, and pain scores. Our results demonstrate that melatonin levels were similar in patients with FMS and healthy controls. Further studies are needed to determine the possible role of melatonin.