the lesser the dose that works, the better.
I started at 10mg...but felt tired and sleepy all day
Down sized to 3mg with good sleep
A side effect of Melatonin is an increase in blood vessel flexibility and resulting drop in BP.
Melatonin and Blood Pressure
Melatonin may also be effective at regulating other bodily functions aside from sleep. Researchers have begun to investigate whether or not melatonin can improve blood pressure readings for those with hypertension. A review in the 2011 issue of "Vascular Health and Risk Management," confirms that there have been several studies on the relationship of melatonin and night blood pressure, and the results are promising, especially for nighttime blood pressure regulation.
During the day, however, any effect on blood pressure was minimal. In addition to its potential for blood pressure regulation, melatonin may improve sleep for some people who take medications to control their high blood pressure.
Certain blood-pressure-regulating medications like beta blockers may interfere with sleep. While melatonin has been studied for its effect on those who use blood pressure medications, the current evidence that it improves sleep for this population is inconclusive. If you are on blood pressure lowering medication, do not take melatonin without your doctor's consent, as it could cause your blood pressure to go too low which could result in shock and serious health consequences, according to the American Heart Association.
Because of its ability to promote sleep, melatonin should be taken before bedtime.
Doctoroz.com recommends taking 0.3 to 1 milligram of melatonin an hour and a half before bedtime. The website warns that taking too much melatonin -- more than 1 milligram -- may have an adverse effect and end up disrupting your sleep cycle.
Lack of sleep may in turn raise your blood pressure according to the American Heart Association.