Our circadian rhythm influences the pharmacokinetics (how the body processes a drug) of many blood pressure (BP) medications. The peak activity of the system that regulates body fluid balance and blood pressure in our bodies, called the renin-angiotensin system, works the best during sleep. This is why a few small studies have suggested that BP medications might be most effective if taken at bedtime.

Research was done on more than 19,000 primary care patients with hypertension. The two groups had similar BP levels and physiological, comorbidity and laboratory (cholesterol) levels. Patients were asked to take their medication regimen either at bedtime or on awakening. Patients were followed with rigorous BP monitoring for about 6.3 years.

The results showed significantly lower BP readings in those that took their blood pressure medications in the evening compared to those taking them upon awakening. The incidence of cardiovascular related death, myocardial infarction, heart failure and stroke was significantly lower in the bedtime group than in the awakening group (6.5% vs 11.9%)- a nearly 50% relative reduction.

This large randomized trial shows convincing evidence that patients with high blood pressure will have better cardiovascular outcomes if they take their medication at bedtime. There was also no adverse events with this group such as fainting or falling on awakening. The only antihypertensive medications that should be taken in the morning are those that have a diuretic such as hydrochlorothiazide.

Reference: Hermida, RC et al. Bedtime hypertension treatment improves cardiovascular risk reduction. The Hygia Chronotherapy trial. Eur Heart J 2019 Oct 22; [epub]. (https://doi.org/10.1093/eurheartj/ehz754).