It is well known that blood pressure is a dynamic indicator, and even in a healthy person it changes during the day. Many factors are involved with this variability including the renin-angiotensin-aldosterone system being most active in the second half of sleep leading to a peak of aldosterone before waking.
The Hygia Chronotherapy Trial is the largest ever study to investigate the effect of the time of day when people take their antihypertensive medication on the risk of cardiovascular events. The trial randomly assigned 19,084 patients to take their medication on waking or at bedtime and followed them for an average of 6 years. Results showed that patients who took their pills at bedtime had a 45 % reduction in overall cardiovascular events. This included a 56 % reduction in cardiovascular death, a 34 % reduction in myocardial infarction (MI), a 40 % reduction in coronary revascularization, a 42 % reduction in heart failure, and a 49 % reduction in stroke, all of which were statistically significant.
Notably that the reductions on cardiovascular events with bedtime dosing were seen with all the different classes of antihypertensive drugs used but a larger effect occurred with ACE inhibitors and ARBs.
Of course, in the age of personalized medicine the doctor individually selects the scheme of antihypertensive therapy for each patient, based on their own experience of clinical practice. However, as demonstrated in the aforementioned RCT, taking antihypertensive medication at bedtime can be more effective and led to an almost halving of cardiovascular events.
