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Take BP pills at night to cut heart risk, study finds

A small switch in your daily schedule could significantly cut your risk of heart attack and stroke, a new study finds.

Taking blood pressure medications at bedtime instead of in the morning reduces the risk of a heart attack and other cardiovascular problems by about two-thirds, Spanish researchers reported.

The new study adds to a growing body of research that suggests blood pressure medication is more effective when taken before going to sleep instead of upon awakening. But the researchers caution that no one should switch from morning to bedtime dosing without first consulting a doctor and having his or her blood pressure monitored over a 24-hour period.

It’s now well-accepted that heart attacks are more common in the morning than the evening, says Michael Smolensky of the biomedical engineering department at the University of Texas at Austin. Smolensky wasn’t a coauthor on the new report but has collaborated with the authors.

Less widely accepted is the notion that blood pressure varies over the course of the day, so one or two readings in the doctor’s office doesn’t tell the whole story, says Smolensky, co-editor of the journal Chronobiology International.

“Mother Nature had in mind that when we went to sleep at night our heart rate and blood pressure would decline” to give our cardiovascular system a rest, Smolensky says. But, he says, people with high blood pressure are less likely to experience that nightly dip, which puts them at a greater risk of complications.

In an email to msnbc.com, lead author Ramon Hermida described bedtime hypertension treatment as “the most effective, cost-free approach to obtain the goal of greater sleep blood pressure reduction.” Still, says Hermida, director of the bioengineering and chronobiology labs at the University of Vigo in Spain, “all patients should be evaluated individually…with ambulatory blood pressure monitoring.”

Monitoring patients’ blood pressure over a day or two is important, because taking medication at night might lower it too much, Smolensky says. That could lead to falls if they got up to go to the bathroom at night or even increase their risk of a stroke because they weren’t getting enough blood to the brain, he says.

Hermida’s new study randomly assigned 661 patients to take all of their prescribed high blood pressure medications upon awakening or to take at least one of them at bedtime. At the beginning of the study, all of them wore ambulatory blood pressure monitors for 48 hours. They were tracked for about 5 ½ years on average and had their blood pressure monitored for 48 hours straight at least once a year.

All of the patients had chronic kidney disease. They represented a subset of patients in a larger study of the timing of blood pressure treatment. That study overall found a similar reduction in risk as it did in the kidney disease patients alone.

“Ours is just the very first trial ever testing the influence on cardiovascular morbidity and mortality of awakening vs. bedtime hypertension treatment,” says Hermida, who published his latest findings in the Journal of the American Society of Nephrology. “Further studies will be needed to corroborate our findings.”