Melatonin and the Metabolic Syndrome

Inclusion Criteria: 1. Age 30-79 years. 2. Diagnosed with metabolic syndrome according to AdenosineTriphosphate-III criteria. 3. Availability for six months after enrolling in the study. Exclusion Criteria: 1. Inability to understand informed consent and to cooperate with study procedures. 2. Supplemental intake of melatonin. 3. Current smoking. 4. Current use of calcium channel blockers. 5. Current, planned, or recent (12 months) participation in another clinical trial. 6. Women who are pregnant, breast-feeding, attempting conception, or planning to attempt conception over the next 6 months. 7. Presence of any of the following diagnosed health conditions: * Active malignancy other than nonmelanoma skin cancer (current therapy for this malignancy,diagnosis within five years of enrollment, recurrence within five years of enrollment, or metastasis) * Uncontrolled hypothyroidism or hyperthyroidism * Recent (\< 1 year ago) history of heart attack, bypass surgery, angioplasty, or stroke * Heart failure (New York Heart Association functional class 3 or 4) * On renal dialysis * Immunosuppressive therapy (systemic corticosteroids, azathioprine, methotrexate, cyclophosphamide, * etc.) or an immunodeficiency syndrome * Narcotic or alcohol dependence * Obstructive sleep apnea (OSA) , defined either by previous diagnosis (with or without use of nasal CPAP), or by a score of 0.80 or higher on the MAP (Multivariate Apnea Prediction), a validated screening algorithm with high positive and negative predictive value for identifying OSA. 8. Shift-workers.