Does melatonin play a role in regulation of 24-hour blood pressure rhythm?

Abstract

Hypertension is one of the most common cardiovascular risk factors. Recent data suggest that not only mean blood pressure values but also short-term blood pressure variability and diurnal blood pressure changes are important. Lack of nocturnal blood pressure decline results in accelerated development of hypertensive endorgan damage and poor cardiovascular prognosis. There are equivocal data regarding potential factors influencing diurnal blood pressure profile. Among other hormonal systems, melatonin was shown to play a role in blood pressure regulation. Its synthesis and release correlate with the day and night cycle. Melatonin has a regulatory effect on many physiological processes including regulation of cardiovascular system and blood pressure. Reduced plasma melatonin levels were found in patients with hypertension, coronary artery disease and acute myocardial infarction. Studies suggest that melatonin therapy may improve blood pressure control and reduce plasma catecholamine levels. The effect of melatonin on circadian blood pressure rhythm is unclear. A relationship between diurnal blood pressure profile and melatonin levels was found in some patients with essential hypertension. Melatonin may influence blood pressure control by various mechanisms, including inhibition of sympathetic activity, improvement of endothelial function, and direct vasodilatation.