According to a new study, people with pre-hypertension who are treated with aspirin may experience significant reductions in blood pressure — but only if they take the pill before bedtime.

People with pre-hypertension (a blood pressure reading between normal and high; when systolic blood pressure is between 120 and 139 or diastolic blood pressure is between 80 and 89 on multiple readings) are at significant risk of hypertension, or consistently high blood pressure — the biggest risk factor for heart disease and stroke, the two leading causes of death in the Western world.

...'[T]aking aspirin before bedtime as opposed to upon waking in the morning is an effective strategy to lower blood pressure...’

"This is the first study to reveal that taking aspirin before bedtime as opposed to upon waking in the morning is an effective strategy to lower blood pressure and cost effective way to individualize treatment regimes in pre-hypertensive patients," said lead investigator Prof. Ramon C. Hermida, Director of Bioengineering and Chronobiology at the University of Vigo in Spain. "These findings therefore have vital treatment implications for these at-risk patients throughout the world."

Although researchers are unsure why aspirin has this impact on pre-hypertensive patients in the evening and not the morning, it could be because aspirin slows down the production of hormones and other substances in the body that cause clotting. Many of those are produced while the body is at rest.

"These results show us that we cannot underestimate the impact of the body's circadian rhythms," said Hermida. "The beneficial effects of time-dependent administration of aspirin have, until now, been largely unknown in people with prehypertension. Personalizing treatment according to one's own rhythms gives us a new option to optimize blood pressure control and reduce risk of cardiovascular disease down the line."