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Melatonin May Be Important for Healthy Blood Pressure Levels

Melatonin is a hormone secreted by the pineal gland in mammals, primarily during sleep. In humans it is a key player in biological rhythms and may also be involved in the onset of puberty. Additional studies have demonstrated that melatonin helps the body maintain a strong immune system. Light exposure during the time when melatonin secretion is at its highest—between 1 and 2 a.m.—causes a decrease in melatonin production and impaired immunity. In fact, in order for the human body to secrete optimal levels of melatonin, complete darkness is required. 

Researchers have found that exposing animals to even minute amounts of light during the night increases their risk of developing cancer. Studies of flight attendants whose biological rhythms are thrown off by air travel through time zones also indicated that their disrupted melatonin production may increase their risk of cancer. Melatonin production also decreases significantly with age, leaving older people vulnerable to decreased immunity. Melatonin first entered the spotlight due to its ability to enhance sleep and reduce the effects of jet lag. But an ever-expanding array of research on this hormone indicates it has a far wider role to play in our health. It has been shown to alleviate migraines and cluster headaches, protect aortic smooth muscular cells against oxidation damage (in vitro), benefit schizophrenia patients with tardive dyskinesia, and (as mentioned above) protect against carcinogenesis. 

Now, a new study indicates melatonin supplementation lowers blood pressure and improves sleep in men with essential hypertension. The study was published in the February issue of the journal Hypertension. It is known that patients with essential hypertension suffer from disturbed circadian pacemaker function. In addition, the biological clock was shown to be involved in certain aspects of cardiovascular regulation. Given this connection between the biological clock and the cardiovascular system, researchers in the Netherlands sought to determine whether nighttime melatonin intake would enhance the functioning of the biological clock and consequently reduce blood pressure in patients with essential hypertension. The authors studied 16 men with untreated essential hypertension. The subjects consumed either a single dose of oral melatonin or repeated doses daily for three weeks (2.5 mg) one hour before sleep. 

The researchers then measured melatonin's effect on 24-hour ambulatory blood pressure and sleep quality. The results indicated that while a single dose of melatonin had no effect on blood pressure, repeated melatonin intake significantly reduced systolic and diastolic blood pressure during sleep. Repeated (but not acute) melatonin intake also improved sleep. The study's authors concluded, “support of circadian pacemaker function may provide a new strategy in the treatment of essential hypertension.”

This article was published on Friday June 08, 2012.
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Scheer FA, Van Montfrans GA, Van Someren EJ, Mairuhu G, Buijs RM. Daily Nighttime Melatonin Reduces Blood Pressure in Male Patients With Essential Hypertension. Hypertension. 2004 Jan 19 [Epub ahead of print].