Data from the Hygia Chronotherapy Trial revealed that not only does taking blood pressure medication at bedtime result in better blood pressure control, but it also markedly reduces the risk of cardiovascular death and events such as a heart attack or stroke.

Hygia is the largest and longest lasting clinical trial to examine the effects of antihypertensive medication timing on the risk of cardiovascular events. The investigators randomly assigned 19,084 adults to take the blood pressure pills that their doctors had prescribed either when they woke up in the morning or at bedtime. During an average follow-up of 6 years, all individuals underwent 48-hour ambulatory blood pressure monitoring at least once per year.

The study shows that, compared with individuals who took their blood pressure pills in the morning, those who took them before going to bed at night had a 45% lower risk of dying from or experiencing cardiovascular events, such as a heart attack, stroke, or heart failure.

The researchers also examined the effect of medication timing on the risk of certain individual cardiovascular events. These analyses showed that, compared with taking blood pressure pills in the morning, taking them at bedtime can reduce the risk of:

• death due to heart or blood vessel conditions by 66%
• stroke by 49%
• heart attack by 44%
• heart failure by 42%
• coronary revascularization by 40%