Hypertension, or high blood pressure, is a condition in which an individual's blood pressure is higher than the normal level. It is estimated that one in three individuals in the United States has high blood pressure, though many do not know it because there are usually no symptoms. Uncontrolled hypertension may lead to stroke, heart attack, heart failure, or kidney failure. Beta-blockers are one class of drugs that have been developed to help lower blood pressure, and thereby decrease the risk for these serious problems. Beta-blockers also lower the levels of melatonin, a hormone that has a sleep-promoting effect. Many individuals who take beta-blockers for hypertension complain that they have trouble sleeping, which may be related to the beta-blockers' effect on melatonin levels. This study will evaluate the effectiveness of treatment with melatonin supplements in improving sleep in individuals with high blood pressure who are taking beta-blockers. In addition, the study will examine whether the melatonin supplements aid in lowering blood pressure.
Participants in this double-blind study will be randomly assigned to receive either melatonin supplements or placebo for the duration of the study. Participants will take part in two inpatient phases. Each inpatient stay will last 4 days and will be separated by 3 to 4 weeks. While in the clinic, participants' sleep patterns and core temperature will be recorded and plasma, saliva, and urine samples will be collected. Blood pressure will be measured before and after each inpatient stay, as well as at points during the stay. Throughout the study, participants' activity will be monitored by an accelerometer worn around the wrist.
