The Best Time to Take Blood Pressure Medication

The typical advice for when to take your antihypertensives (high blood pressure medication) has been to take it in the morning. However, there’s growing evidence that most blood pressure medications are more effective when people take them at night.

This is largely due to a concept called chronotherapy. It is an approach to the timing of medical treatment based on circadian rhythms, the body’s natural cycle of physical changes that take place every 24 hours. The approach has been used to find the best times of day to treat other medical conditions, including sleep apnea, chronic kidney disease, and diabetes.

This article explains how different types of blood pressure medications work. It looks at how blood pressure naturally tends to rise and fall, and how the best time to take your medication may be influenced by chronotherapy principles.

How Blood Pressure Medication Works

There are 11 categories of blood pressure medication. Each works in different ways, with the overall goal of lowering the pressure in the blood vessels and sometimes also reducing the work that the heart has to do.

• Diuretics flush excess fluid and sodium out of the body to reduce blood volume and pressure in the blood vessels.
• Beta-blockers make the heart beat more slowly. They reduce how hard it has to work.
• ACE inhibitors help to reduce the amount of a hormone called angiotensin. This hormone causes arteries to narrow.
• Angiotensin II receptor blockers block the receptors for angiotensin to prevent it from narrowing arteries.
• Calcium channel blockers relax and dilate (widen) blood vessels, decreasing pressure in the vessels. They also lower the heart rate.
• Alpha-blockers help to relax the walls of blood vessels.
  
• Alpha-2 receptor agonists lower the activity of the sympathetic nervous system. This is a part of the nervous system that controls heart rate and other involuntary body functions.
• Combined alpha- and beta-blockers are used for the treatment of heart failure; they are sometimes prescribed for treating a hypertensive crisis.
• Central agonists make it harder for blood vessels to contract (narrow).
• Peripheral adrenergic inhibitors block chemicals in the brain that play a role in causing blood vessels to become narrow.
• Vasodilators relax the walls of blood vessels. This helps them to widen and lowers blood pressure.
  

When Is Blood Pressure Highest?

Blood pressure rises and falls in a fairly predictable pattern. When you wake up in the morning, it surges. It then increases throughout the day. At night, during sleep, it tends to drop again.

However, this isn’t always the case for people with high blood pressure. In fact, there are four distinct patterns of nighttime blood pressure shifts.

They are:

• A normal drop in blood pressure of 10% to 20%
• Extreme dipping, which is a drop of more than 20%
• Non-dipping, which is a drop of less than 10%
• Reverse dipping, in which blood pressure is higher during sleep than during waking hours

All three types of abnormal dips in blood pressure are associated with various health risks. They can affect the arteries and heart, kidneys, blood sugar levels, and more.

The only way to know how your blood pressure changes is to measure it regularly at different times across the day and night. One way to do this is with ambulatory blood pressure monitoring (ABPM).

This technique involves wearing a blood pressure cuff like the one your healthcare provider uses in their office. The cuff is linked to a small monitor that can be attached to a belt or an item of clothing. The device automatically takes your blood pressure every 15 or 30 minutes. You use it for a specified period of time, usually 24 or 48 hours.

Advantages of Medicating at Night

Quite a few studies suggest that blood pressure medications may work best when taken at night.

The biggest and most significant of these was the Hygia Chronotherapy Trial. It was a six-year study of more than 19,000 people with high blood pressure.

The researchers divided the participants into two groups. One group took their blood pressure medication in the morning. The other took them at night. At least once a year, all of the participants used ABPM to record their blood pressures.

The researchers found that when compared to the morning group, those who took their blood pressure treatment at night had a lower risk of getting (or dying from) a number of conditions.

For the nighttime medication group:

• The risk of stroke was lower by 49%.
• The risk of heart attack was lower by 34%.
• The risk of heart failure was lower by 42%.

A 2015 study in the journal Diabetologia found that taking these medications at night reduced the risk of type 2 diabetes for people with high blood pressure. Other studies report possible advantages of taking blood pressure medication at night. One is that many people are more likely to take their medication before bed rather than in the morning. Another is that the effects of these treatments may wear off more slowly when they are taken at night than when people take them in the morning.

None of this is to say you should never take your blood pressure medication in the morning. In fact, this might be better if you take diuretics. They work by helping the kidneys to get rid of excess fluid in the body. They can cause you to urinate more, which may mean more trips to the bathroom at night.

Summary

For some time, people have been told to take blood pressure medications in the morning, when blood pressure tends to surge. The morning hours are also when heart attack, stroke, and other emergencies associated with high blood pressure tend to happen.

There’s growing evidence, though, that it may be best to take these medications at night, before sleep. Studies have found that this timing may reduce the risk of developing some serious health conditions, like heart failure. Be sure to ask your healthcare provider about the best schedule and timing for all your medications.