Nocturnal blood pressure predicts heart attack and stroke. An exercise tweak can help fix it.

Sometime between midnight and 6am, while you’re deep in sleep, your blood pressure (BP) should be falling. Whether it does — and by how much — is one of the strongest predictors of your cardiac future. 

“In a healthy individual, blood pressure usually goes down at night. We call it a dip,” says Nieca Goldberg, MD, a cardiologist and Clinical Associate Professor at NYU Grossman School of Medicine. “Individuals who don’t dip and have high blood pressure at night are the individuals who are going to have hypertension,” she explains.

As red flags go, it’s an easy one to miss — occurring while you’re unconscious and showing up nowhere near a typical doctor’s visit. A September 2022 study from the UK found that 15% of adults aged 40-75 may have undiagnosed nocturnal hypertension. That’s concerning, since recent research shows that nocturnal blood pressure may be a stronger marker for cardiovascular disease and death than daytime readings. If your numbers remain high after hours, these risks increase.

The good news: Exercise can help you build and maintain the nighttime dip that we now know is crucial to lifespan and healthspan[helth-span]nounThe number of years you live in good health, free from chronic illness or disability.Learn MoreClose. And high-intensity interval training (HIIT) can provide an additional boost by lowering diastolic blood pressure (the “bottom number” of blood pressure) modestly better than steady-state cardio work. 

But HIIT isn’t the only way to improve it. Ahead, experts dive into why nocturnal blood pressure matters, how to measure it more accurately, and which mix of cardio can give your numbers a boost by lowering them. 

Why Nocturnal Blood Pressure Matters

During the day, your blood pressure is considered “normal” when it’s below 120/80 mmHg. But between 10pm and 6am, the bar is lower: the American Heart Association says that a healthy nocturnal dip should bring blood pressure down to 110/65 mmHg.

According to a 2023 study, people whose blood pressure only spiked at night while appearing normal during daytime readings were 38% more likely to experience a serious cardiac event like a heart attack or stroke, and 29% more likely to die from any cause over the following 7-8 years. That held true even after accounting for age and other health conditions.

When your blood pressure doesn’t dip, the consequences can also extend well beyond the heart. Elevated nighttime blood pressure is also associated with kidney disease, eye disease, microbleeds in the brain, cognitive dysfunction, and falls. 

Why do people sometimes skip the dip? In certain cases, it’s medication timing — blood pressure drugs taken in the morning may lose their effect by bedtime. But lifestyle factors can also play a role: a high-salt diet, stress, obesity, and sleep problems can also blunt or eliminate a heart-healthy nighttime dip of 10-20%. 

How to Measure Your Blood Pressure

If you’re at risk for high blood pressure, or if “white coat” hypertension causes your blood pressure to rise during check-ups, your doctor may recommend trying a 24-hour ambulatory blood pressure monitor. This monitor includes an arm cuff and a machine, usually worn around the waist, that records readings every 15-60 minutes, including while you sleep. 

However, most people don’t need 24-hour monitoring to get the information they need, Goldberg says. That’s good news, since wearing a 24-hour monitor can disrupt your sleep when the cuff tightens in bed. A simpler habit can tell you a lot: take your blood pressure twice a day — once in the morning, once before bed — and track how it changes. Most people only measure in the morning, but that second reading (and the opportunity for comparison) is where the real story lives.

To get an accurate reading at home, Goldberg recommends the following:

1. 1. Sit in a chair with back support, your feet flat on the floor.
2. Rest your arm on a table at heart level, as you would in your doctor’s office. 
3. Sit still during the reading. No phones, no talking.
4. Take your readings at the same times each day, in the same physical state, so that you can track changes.

Once you have that data, bring it to your doctor, especially if your evening readings are elevated, don’t dip, or shift over time. 

Shawn Arent, Ph.D., C.S.C.S., chair of the Department of Exercise Science at the University of South Carolina, has another suggestion: put on your scientist hat. Identify four or five things you could be doing to prepare yourself for better sleep, as well as the things that could be elevating blood pressure, he suggests. In the latter group, common culprits include eating a large, late meal, doom-scrolling before bed, or drinking alcohol at night. “Try manipulating one or two of those at a time, and see what it does to your readings,” he tells Super Age.

HIIT Helps Nocturnal Blood Pressure. So Does “Normal” Cardio.

High-intensity interval training, which alternates intense bouts of exercise with periods of rest or easier work, has earned its reputation in the longevity world. It has been found to reduce waist circumference, lower resting heart rate, improve VO2 Max[vee-oh-too maks]nounA measurement of how much oxygen your body can use during exercise.Learn MoreClose and mitochondrial function, and even boost cognitive function. And yes, it also helps with lowering nocturnal blood pressure.

In a 2019 research analysis, three studies found that HIIT helped reduce nighttime systolic and diastolic blood pressure, and did so better than slower, steady-state cardio work. Some of those findings were modest: one study found that 6 weeks of HIIT reduced nighttime diastolic blood pressure by 3.5 points. By comparison, 40 minutes of moderate-intensity cardio, done over the same period, reduced it by 3 points. 

But here’s a number worth sitting with: Averaging all three studies in the review, HIIT improved nocturnal diastolic blood pressure by an average of around 6 points, while moderate cardio improved it by around 3. 

Arent says the takeaway is that HIIT appears to be modestly more beneficial, but that any exercise can improve your numbers. He cautions against interpreting the results as meaning “HIIT helps, but steady-state doesn’t.” 

“These are both meaningful improvements,” Arent says. “They both work.”

That matters, because truly intense HIIT — the kind where you’re pushing to 90–95% of your maximum heart rate for four-minute stretches — is genuinely hard. For people who are already hypertensive or on blood pressure medication, it can also be risky, since intense exercise temporarily elevates blood pressure while you’re moving, Goldberg notes. If that’s your situation, talk to your doctor before going all-out.

And even for people who enjoy high-intensity work, doing it multiple times a week isn’t sustainable, Arent says. The doctor, a heart patient himself, says he mixes weekly HIIT sessions with moderate-intensity cardio rather than choosing between them.

“We’re doing ourselves a massive disservice by always comparing these things,” he says, “because we treat it as an ‘either/or,’ when to me it’s ‘and both.'”

Your Prescription: 150 minutes of weekly cardio, with one or more HIIT sessions (assuming your doctor agrees that it’s safe and beneficial). Doing this much exercise each week can make you 14 percent less likely to suffer from coronary diseases, and 31 percent less likely to die early. Adding a HIIT session can further help with nocturnal blood pressure, and by increasing the amount of your weekly exercise that’s vigorous, reduce your risk of cardiovascular events by 31 percent more than steady-state work alone. 

How you move during the day shapes what happens in the hours after midnight — and that, it turns out, is where your cardiac future is being written.

The perspectives of the experts quoted are independent of the sponsor and no compensation was received. This content does not replace professional medical advice. Consult a qualified healthcare provider for questions about diagnosing or treating hypertension and before engaging in any sort of exercise regime; do not delay seeking care or medical advice because of this article.