The immune - pineal system, formed by the integration of the adrenergic and immune systems pineal gland, appears to be involved in the genesis of the dysfunctions found in fibromyalgia. Melatonin is secreted by the pineal gland and has promoter activity of sleep. Studies show that melatonin and its precursors , serotonin and tryptophan are reduced in patients with fibromyalgia.