Results of a recent study suggest that melatonin may have a beneficial effect on blood pressure. The study, published in the Jan. 20, 2004, rapid-access issue of Hypertension, showed that taking melatonin at bedtime for three weeks lowered blood pressure among 16 men with untreated hypertension. However, a single dose of melatonin had no effect at all on blood pressure.
The researchers - from Harvard Medical School and Brigham and Women's Hospital in Boston - theorized that melatonin may affect blood pressure via its effect on the body's biological clock. But since taking melatonin also improved sleep among the study's subjects, the researchers haven't been able to rule out the possibility that sleeping better might also have helped with blood pressure reduction.
While these results are interesting, they'll have to be confirmed in larger studies before we can be sure that melatonin really does lower high blood pressure. If so, melatonin may be used in addition to - or instead of - medications now used to control blood pressure. And, of course, studies will be needed to determine how melatonin interacts with the various drugs currently used to treat hypertension.
Like high cholesterol, high blood pressure is a risk factor for heart disease. You may be able to bring your pressure down without medication by discontinuing all stimulants, including coffee and tobacco, taking supplemental calcium and magnesium, (however, I don’t recommend supplemental calcium for men)and sticking to a low-fat diet that is rich in fruits and vegetables. Lower your salt intake and, if you're overweight, try to get your weight within five pounds of your ideal weight. Regular exercise and practicing relaxation techniques to counteract stress are also very important.
As far as melatonin is concerned, until we know more about its effect on blood pressure, I suggest using it only occasionally as a remedy for jet lag. Take a 2.5 mg sublingual (under the tongue) tablet for a night or two after arriving in a distant time zone.
Andrew Weil, M.D.