Melatonin Reduces Nighttime High Blood Pressure

Healthnotes Newswire (November 30, 2006)—A hormone known as a treatment for insomnia and sleep disorders may have a new use: lowering high blood pressure. Melatonin, which regulates sleep cycles, has been shown in a new study to lower blood pressure in people with nighttime high blood pressure (nocturnal hypertension).

“People with high blood pressure may have disturbances of their biological clocks,” said Ehud Grossman, MD, of the Department of Internal Medicine D and Hypertension Unit at the Chaim Sheba Medical Center in Tel Hashomer, Israel. “Their nighttime blood pressure may not fall to normally lower levels. These people appear to be at particularly high risk of cardiovascular events, such as heart attack and stroke.”

Blood pressure, like many other body functions, has a daily rhythm. It normally goes down at night while you sleep. In the morning when you rise, your blood pressure rises as well, peaking in the mid-afternoon. In the late afternoon and evening, blood pressure once again starts to go down.

Nocturnal hypertension is associated with a high risk of disease and death. It is a better predictor of cardiovascular risk than daytime blood pressure. The body’s melatonin processing appears to be impaired in people with nocturnal hypertension, leading to a possible deficiency of the hormone. However, in previous studies taking melatonin appeared to interfere with the blood pressure–lowering activity of some hypertension medications.

Grossman and colleagues tested 38 people who were managing their hypertension with drugs, so the researchers were able observe if there was any interaction between the drugs and melatonin supplements. The participants were randomly assigned to receive 2 mg of controlled-release melatonin or a placebo two hours before bedtime, nightly for four weeks. Special 24-hour blood pressure–monitoring equipment was used to assess changes in blood pressure.

At the end of four weeks, those taking melatonin supplements had significantly reduced nighttime blood pressure, whereas the placebo had no effect.

“Our results suggest that melatonin supplements improve nighttime blood pressure control in treated patients with nocturnal hypertension,” concluded Grossman. “Though its exact mechanism is unknown, melatonin appears to influence how the nervous system regulates blood vessel dilation and pressure. Larger, long-term studies using varying amounts of melatonin are now needed to confirm these preliminary findings.”

(Am J Med 2006;119;898–902)

Jeremy Appleton, ND, CNS, is a licensed naturopathic physician, certified nutrition specialist, and published author. Dr. Appleton was the Nutrition Department Chair at the National College of Naturopathic Medicine, has served on the faculty at Bastyr University of Natural Health Sciences, and is a former Healthnotes Senior Science Editor and a founding contributor to Healthnotes Newswire. He has worked extensively in scientific and regulatory affairs in the supplement industry and is now a consultant through his company Praxis Natural Products Consulting and Wellness Services.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.