The hormone melatonin helps lower blood pressure and also helps senior citizens get a better night's sleep.

As we age, blood pressure increases and becomes more irregular, and the circadian rhythm, which control the body's wake and sleep cycles, functions less efficiently. A study published in the journal Current Aging Science found that melatonin helps both problems.

Researchers studied volunteers whose median age was 80. During the first week of the study, data on blood pressure and sleeping habits was collected. During the following two weeks, seniors were given a low dose (1.5 mg) of melatonin at 10:30 each night, then data was collected again and assessed.

Melatonin significantly reduced blood pressure, and the amount depended on time. The maximum lowering of systolic blood pressure fell between 3:00 and 8:00 in the morning, the time of the highest risk of heart attacks and strokes. Nighttime and morning BP decreased on average 8 mmHg for systolic pressure readings and 3.5 mmHg for diastolic readings.

In addition, the higher the systolic reading was the first week, the more it dropped after melatonin was added. The blood pressure rates also became more regular.

Melatonin also helped smooth the circadian rhythms, an effect found in none of the seniors who received a placebo.

According to the Centers for Disease Control and Prevention, more than half of Americans aged 55 and older have high blood pressure. High blood pressure can lead to heart attack, heart failure, stroke, aneurysms, kidney failure, and other major health problems.