Melatonin lowers elevated nocturnal blood pressure

Townsend Letter for Doctors and Patients, Feb-March, 2007 by Alan R. Gaby

Thirty-eight hypertensive patients (mean age, 64 years) with nocturnal hypertension (mean systolic blood pressure > 125 mm Hg, according to repeated 24-hour ambulatory blood pressure monitoring) who were on stable doses of antihypertensive medication were randomly assigned to receive, in double-blind fashion, 2 mg of sustained-release melatonin or placebo two hours before bedtime for four weeks. Nocturnal systolic blood pressure decreased from 136 mm Hg to 130 mm Hg in the melatonin group (p = 0.011, compared with baseline; p = 0.01, compared with placebo). The reduction in systolic blood pressure was most pronounced between 2 AM and 5 AM (p = 0.002).

Comment: Blood pressure normally declines at night. An impaired nocturnal blood pressure decline is associated with a high risk of cardiovascular events and mortality. Hypertensive patients who do not show a normal nocturnal blood pressure decline have been shown to have a blunted nocturnal surge of melatonin secretion. The results of the present study indicate that the addition of 2 mg of melatonin at night to stable antihypertensive treatment improved nocturnal blood pressure control in patients with nocturnal hypertension.

Grossman E, et al. Melatonin reduces night blood pressure in patients with nocturnal hypertension. Am J Med. 2006;119:898-902.