Melatonin Improves Mood Status and Quality of Life and Decreases Cortisol Levels in Fibromyalgia

Background: Mood disturbances are implicated in the pathogenesis of fibromyalgia. The aim of this study was to assess the effect of different doses of melatonin on quality of life, mood status, pain, anxiety, and urinary cortisol levels in patients with fibromyalgia. Methods: After a 10-day baseline period for the collection of data about participants' initial status, participants took different doses of melatonin for 10 consecutive days each, with placebo given during the 10 days either before or between melatonin doses. Participants' moods, quality of life, and pain levels were assessed using the Fibromyalgia Impact Questionnaire (FIQ), a Numerical Pain Scale (NPS), the State-Trait Anxiety Test (STAI), a Visual Analog Scale (VAS), and the Short Form-36 Health Survey (SF-36). Urinary cortisol levels were measured using enzyme-linked immunoassay. Results: Doses of 9, 12, and 15 mg of melatonin were associated with decreases in the total score of the FIQ, NPS scores, and urinary cortisol levels. The State-Anxiety subscale of the STAI improved after the 12 mg dose. The scores on the VAS improved after the 9 mg dose. The dimensions evaluated in the SF-36 questionnaire improved after the 9 mg dose. Conclusion: Melatonin improved mood, anxiety levels, and quality of life while decreasing cortisol levels in patients with fibromyalgia.