Melatonin May Cut Hypertension Risk

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Melatonin May Cut Hypertension RiskJanuary 19, 2004 01:04:14 PM PST , HealthDay

By Amanda Gardner

HealthDay Reporter MONDAY, Jan. 19 (HealthDayNews) -- Melatonin may do more than

cure jet lag.

Researchers have found taking supplements of the hormone at night helped reduce

blood pressure levels in a small number of men.

Pending further investigation, this over-the-counter supplement could join the

arsenal of effective blood pressure treatments, the authors of a new study say.

Researchers have learned recently that people suffering from high blood pressure

have disturbances in their biological clocks, which are tied to light and dark

and regulate sleep patterns. Exactly how the two are linked is not yet known.

" There is an early morning peak in cardiovascular incidents [heart attacks], "

says Frank A.J.L. Scheer, lead author of the study appearing in the February

issue of Hypertension.

" Since in the early morning there are also changes induced by the circadian

rhythm [biological clock], a hypothesis was that disturbances of this circadian

rhythm might be one of the underlying mechanisms of this increased peak in the

early morning. And that by restoring the anticipatory functionality of the

biological clock [with melatonin], we might be able to counteract that, " Scheer

adds.

Scheer is a neuroscientist at Brigham and Women's Hospital and Harvard Medical

School Division of Sleep Medicine, both in Boston.

Others caution it's too early to draw any firm conclusions about melatonin's

ability to control blood pressure.

" It's obviously a wait-and-see situation, " says Dr. Michael Schloss, co-director

of the New York University Lipid Treatment and Research Center and a clinical

associate professor of medicine at NYU School of Medicine.

Melatonin is a hormone produced by the body's pineal gland. As darkness arrives,

the pineal gland kicks into action. As melatonin production rises, people start

to feel less alert and sleepy. Melatonin levels decline with sunrise, and remain

low throughout the day.

Scheer and his colleagues looked at 16 men, all of whom had untreated high blood

pressure, at the Netherlands Institute for Brain Research in Amsterdam. The men

were randomly assigned to receive either a placebo, a single dose of melatonin

or 2.5 milligrams of melatonin one hour before bedtime for three weeks. The

study was designed so all the men would be assigned to each group at one point.

While the men taking the placebo or the single dose of melatonin experienced no

change in their blood pressure, those taking the hormone each night throughout

the three weeks had lower nighttime systolic and diastolic blood pressure.

Systolic blood pressure (the top number in the reading) decreased by an average

of six millimeters of mercury while the diastolic blood pressure (the bottom

number) decreased by an average of four millimeters of mercury.

Participants taking melatonin also reported sleeping better, but this was not

necessarily related to changes in their blood pressure.

" We did not find such a correlation in this study, " Scheer says. " We, however,

don't exclude that chronically improved sleep may also contribute to the lower

blood pressure. The improvement of sleep by repeated and not by single melatonin

actually further supports the hypothesis of the increase in the circadian rhythm

output of the biological clock. "

No one is sure why these changes took place, only that they are potentially

significant. People are asleep for about a third of their lives, the study

authors point out, and nighttime blood pressure seems to be a better predictor

of cardiovascular risk than daytime blood pressure. Melatonin may be effective

in reducing morning blood pressure, which may be contributing to the increased

risk at that time, the study authors say.

Still, experts, including the study authors, caution patients not to do anything

just yet.

" From a medical point of view, more patients need to be studied, " Scheer says.

" Also, in our study the patients were untreated by any other medication and

because many people with hypertension are treated already by regular

hypertensive drugs, it also would need to be established how co-treatments would

affect the blood pressure. "

 

 

 

 

 

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