Blood pressure-lowering medications work much better if they are taken at bedtime rather than in the morning, according to a landmark study that could transform the way hypertension is treated.
While previous research has indicated that the timing of the dose may be critically important, the new study is the first human trial to show that this simple change in the daily schedule of patients may reduce the risks of cardiovascular disease and save lives.
The findings are based on a group of 661 patients afflicted with chronic kidney disease and hypertension. About half the patients took all their blood pressure-lowering medications when they woke up each morning and half took at least one of the drugs at night.
After an average of 5.4 years of follow-up, the blood pressure of those who took medication at bedtime was better controlled. Even more important, they were one-third less likely to have suffered a heart attack, stroke or heart failure than patients who popped all their pills in the morning.
"This is very, very relevant for patients," said the lead researcher, Ramon Hermida of the University of Vigo in Spain.
The study is part of a growing field of research known as chronotherapy, in which medical treatments are timed to correspond to the body's 24-hour circadian rhythm.
Dr. Hermida noted that the cardiovascular system goes through a daily cycle, with blood pressure normally rising in the morning and dipping at night. If blood pressure remains elevated at night, the heart doesn't have a chance to rest, which increases the long-term risk of cardiovascular disease.
"Night time blood-pressure control can be best achieved by taking the hypertensive medications in the evening," he said, adding that many of the body's mechanisms for regulating blood pressure are activated at night.
Yet the vast majority of patients are in the habit of consuming their pills in the morning.
Does this mean that all hypertension patients should start taking their meds before they slip between the sheets? Dr. Hermida cautioned that the results of his study, published in the Journal of the American Society of Nephrology, must first be confirmed by a much larger trial (one is already in the planning stages).
Furthermore, patients should be properly evaluated to determine if they actually suffer from elevated blood pressure at night. Most patients, he noted, have their blood pressure measured at a doctor's office during the day, a practice that may not provide an accurate reflection of their real medical condition. Some people suffer from "white-coat syndrome" in which the sight of a physician sends their blood pressure skyrocketing but it returns to normal when they leave the medical clinic.
For the Spanish study, each patient initially wore an electronic monitoring device that took regular blood pressure readings for 48 hours. This added level of testing "is highly cost-effective because you identify those people who really should be treated," said Dr. Hermida.