Blood pressure refers to the force exerted by circulating blood on the walls of your arteries – the blood vessels responsible for transporting blood from your heart to your brain and throughout your body.

A certain level of pressure is required to maintain adequate blood flow; however, consistently elevated pressure can overburden the heart, resulting in heart and circulatory ailments such as heart attacks or strokes.

High blood pressure, also known as hypertension, is linked to nearly 50% of heart attacks and strokes. In the United States, approximately 47% of adults (totaling 116 million) suffer from hypertension, which is characterized by systolic blood pressure exceeding 130 mmHg or diastolic blood pressure surpassing 80 mmHg.

Despite these efforts, the CDC reports that a mere 24% of adults with hypertension successfully keep their condition in check.

Lifestyle factors, such as diet, smoking, and alcohol consumption, may contribute to hypertension, with many individuals remaining unaware of their condition.

To manage this condition, many individuals rely on medications like diuretics, commonly referred to as water pills.

A recent study, published in Renal Physiology and conducted by researchers at the University of Waterloo indicates that the efficacy of diuretics, a common hypertension treatment, may be influenced by the time of day and the patient’s gender.

Both biological sex and the body’s circadian rhythm play essential roles in blood pressure regulation.

The circadian rhythm is an innate, internal mechanism governing various physiological processes, including the sleep-wake cycle, with a duration of approximately 24 hours.

Among other functions, the circadian rhythm also controls kidney function, which is vital in regulating blood pressure through the maintenance of fluid and electrolyte balance in the body.

“One important class of blood pressure medication is diuretics, sometimes called water pills,” remarks corresponding author Anita Layton.

Diuretics contribute to blood pressure reduction by focusing on renal function to enhance the volume of urine expelled by the body. When their performance falters, it may adversely affect blood pressure levels.

The research team led by Layton employed mathematical modeling to evaluate the efficacy of various diuretic drugs on kidney function in male and female mice. The study focused on three types of diuretics: loop, thiazide, and potassium-sparing.

To conduct the experiment, they first simulated the circadian rhythms of the mice, accounting for their nocturnal nature with active periods during the night and inactive periods during the day.

They then analyzed the expected urine output and sodium excretion for each type of medication at different times of day in both male and female mice.

The results revealed that drug effectiveness varied depending on the diuretic category, the sex of the mice, and the time of day the drug was administered.

Although humans typically exhibit opposite circadian patterns, being active during the day and resting at night, the study’s findings imply that individuals can optimize their blood pressure treatment by strategically timing their medication intake.

“Chronotherapy, which is the tailoring of drug administration to match the body’s circadian rhythms,” adds the author, “can play a major role in improving modern personalized medicine.”

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