Specifically, the study found that people who take the medications before falling asleep at night are almost half as likely to experience or die from heart attacks, strokes, heart failure or other heart or blood vessel conditions as people who take them upon awakening in the morning.
It’s not clear why the drugs worked better when taken at bedtime, but the researchers believe it’s related to the body’s circadian rhythms, the internal biological “clocks” that set the timing of the body’s physiological functions.
“The same medication ingested at different times of the day actually has different pharmacological properties, behaving like totally different medications,” explained Ramón Hermida, the study’s lead author and a chronobiologist at the University of Vigo in Spain, in an interview with NBC News.
If confirmed with further research, the study’s findings are likely to change the daily medicine-taking routine for about 52 million Americans — the seven in 10 U.S. adults with high blood pressure (hypertension) who use prescription drugs to control the condition.
As Hermida points out in a released statement, “Current guidelines on the treatment of hypertension do not mention or recommend any preferred treatment time. Morning ingestion has been the most common recommendation by physicians based on the misleading goal of reducing morning blood pressure levels. “
How the study was done
For the study, Hermida and his colleagues recruited 19,084 patients (median age: 60) who were being treated with medications for high blood pressure in 40 clinics throughout Spain. They randomly assigned the patients to take all their blood pressure pills either before bedtime or upon waking in the morning. Importantly, they didn’t give the patients a specific time, as individual sleep-wake cycles vary from person to person, depending on their internal circadian rhythms.
The patients were followed for an average of six years and three months. Their blood pressure was measured at the start of the study and at every subsequent clinic visit. In addition, at least once a year, the patients wore a portable blood pressure device that continually recorded their blood pressure for 48 hours. These readings enabled the researchers to see if the patients’ blood pressure “dipped” while they were sleeping.
Blood pressure normally falls during sleep — by about 10 to 20 percent. But that is not the case for everyone, and some people even experience a rise in blood pressure while sleeping. Some research suggests that blood pressure at night is an important predictor of cardiovascular problems.
What the study found
During the study’s follow-up period, 1,752 patients had a major cardiovascular “event,” such as a heart attack or stroke, and 310 of them died as a result.
The researchers then examined the data to see if they could find any differences in health outcomes between the “morning” and “evening” pill takers.
They found marked differences. The people who took their medications at bedtime were 45 percent less likely to have experienced a heart attack, stroke or heart failure — or to have undergone a procedure to open clogged coronary arteries — during the study period than those who took their pills in the morning.
Furthermore, their risk of dying from cardiovascular-related problems during the study period was 56 percent lower than the before-bed pill takers.
The researchers believe these better outcomes are linked to better nighttime blood pressure control. Data from the 48-hour blood pressure monitoring showed that the average blood pressure of the evening pill takers was significantly lower both at night and during the day than that of the morning ones. Their blood pressure also dipped more while they slept.
Talk with your doctor
The research comes with several important caveats. Most notably, the participants were white adults living in Spain, so the results may not be applicable to other populations. In addition, none of the patients worked night shifts, so it’s unknown how the timing of blood pressure medications would affect that group.
Another limitation is the fact that the participants were prescribed different types of high blood pressure medications — ones chosen by their individual doctors. Those differences may have affected the results.
Still, the study is robust enough to make the findings encouraging, for they suggest that a simple switch in the timing of taking blood pressure pills may help millions of people lower their risk for heart attack, stroke and premature death.
“The results of this study show that patients who routinely take their anti-hypertensive medication at bedtime, as opposed to when they wake up, have better-controlled blood pressure and, most importantly, a significantly decreased risk of death or illness from heart and blood vessel problems,” says Herida.
Of course, no one should change how they take a prescribed medication without first talking with their doctor. There are many reasons doctors advise patients to take a drug at a certain time of the day, including avoiding adverse reactions with other medications.
FMI: You’ll find the study on the European Heart Journal’s website.