Chronic Supplementation of Melatonin restores Impaired Circadian Rhythm in Patients with Coronary Artery Disease

Blood pressure (BP) has a characteristic and reproducible circadian pattern with high values during the day and low values at night. Previous studies have shown that in patients with coronary artery disease (CAD), the nocturnal dip of BP is absent or blunted, which may be correlated to the reduced melatonin levels or altered melatonin-cortisol interplay. Our objective was to assess the effect of bedtime melatonin administration on circadian pattern of BP and heart rate (HR) in CAD patients. One hundred CAD patients were recruited for the study. General health records were individually maintained. Each study participant was given a 5 mg pure melatonin supplement each night at bedtime for a period of 1 year. A 24 hour/7 day ambulatory blood pressure monitoring (ABPM) using ambulatory blood pressure monitor and serum melatonin level estimations were done initially, after 6 months, and after 1 year of melatonin supplementation. The rhythmic parameters of systolic BP (SBP) and diastolic BP (DBP), HR, viz. midline-estimating statistic of rhythm (MESOR), double amplitude, acrophase, 3 hour fractionated hyperbaric index (HBI) were significantly reduced and serum melatonin concentration significantly increased after 6 and 12 months of exogenous melatonin supplementation. Circadian hyperamplitude tension (CHAT) incidence decreased as melatonin treatment progressed. The number of subject diagnosed with CHAT was as follows: 37/100 at the beginning, 17/100 after 6 months, and 6/100 after 12 months. These data suggest that 5 mg/day melatonin treatment improved and restored the circadian pattern of BP in CAD subjects.