As our bodies internal clocks determine that it is time for sleep, triggered largely by the change from daylight to darkness at night, we produce the hormone like substance melatonin that causes sleepiness. As melatonin levels rise in the blood, blood pressure levels fall during nightly sleep. Italian researchers speculate that melatonin may decrease noradrenaline (norepinephrine) levels, increase nitric oxide production, and lessen resistance to blood flow within large arteries. All those effects would be expected to lower blood pressure.
So the doctors at a clinic in Modena decided to evaluate the effect of melatonin on the daily blood pressure variance in nine women with normal blood pressure and another nine whose hypertension was being treated with ACE inhibitor drugs. Their ages ranged from forty-seven to sixty-three. For three weeks, the women were randomly assigned to melatonin or a placebo. During the next three weeks, the groups "crossed over" to get melatonin if they had been taking placebo and vice versa.
Melatonin treatment decreased both systolic and diastolic nightly blood pressure by 3.77 and 3.63 points overage. Some women had as much as a 10-point blood pressure decline during the night's sleep. Women who normally had the least reduction in nocturnal blood pressure showed the greatest improvement.
There was no change in blood pressure during the day, which was to be expected since melatonin levels disappear or diminish after awakening. But the difference between nocturnal and diurnal blood pressure intensified, and that difference has been linked with heart disease. The greater the difference between blood pressure during the day and during the night, the better.
Similar research has been conducted at Harvard University, where investigators gave melatonin to sixteen men over a three week period. A single dose of 2.5 mg did no good, but taken nightly over the course of the three weeks, it reduced systolic and diastolic blood pressure on average by 6 and 4 points respectively. The difference between blood pressure during the day and during the night was increased by 15 percent systolic and 25 percent diastolic. Subjects enjoyed better sleep as well, although the improvement in sleep was not related to the blood pressure improvement.
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Originally Posted by ineedtogrow
