Lack of Sleep and Blood Pressure: What Really Happens

You probably already know that getting enough sleep helps you feel rested and focused. But those seven to eight hours each night also give your cardiovascular system time to recover. During deep sleep, your heart rate slows and blood pressure naturally dips, giving your blood vessels a break from the day’s workload.

When you regularly get less than the recommended amount of sleep (about seven to nine hours for most adults) that recovery period shortens. Over time, your body stays in a low-grade “on” mode, with stress hormones and heart rate running higher than they should. “Sleep is one of the body’s strongest regulators of blood pressure,” says Serena Pratt, M.S., RD, a registered dietitian who specializes in cardiometabolic health. “When sleep is cut short, the nervous system doesn’t fully relax, so blood pressure can stay higher even during rest.”

Here’s what happens inside your body when you don’t get enough sleep, and why those late nights might be quietly raising your blood pressure in the background.

How Poor Sleep Impacts Blood Pressure

Your Body Stays Stuck in Stress Mode

When you don’t get enough sleep, your body doesn’t have the chance to fully switch from “fight or flight” mode into rest and recovery. The sympathetic nervous system stays active, keeping heart rate and stress hormones like cortisol and adrenaline elevated. “When people routinely sleep less than seven to eight hours, the body shifts into a chronic stress mode,” explains Pratt. That stress response “increases heart rate and constricts blood vessels, which can raise blood pressure around the clock,” she continues. Research has shown that short sleep duration is associated with both higher daytime and nighttime blood pressure levels compared to normal sleep.

It Increases Fluid Retention

Sleep deprivation doesn’t just stress the nervous system; it can also alter hormonal systems that control blood pressure. Poor sleep can make the renin–angiotensin–aldosterone system more active, leading the kidneys to hold onto sodium and water, explains Pratt. Over time, this increases blood volume, which makes it harder for the heart to pump efficiently.  Sodium regulation becomes less effective when the body misses out on deep, restorative sleep, adds dietitian Bess Berger, RDN, CDN, CLT. Together, this combination of hormone imbalance and fluid retention can gradually push blood pressure higher, even in people who follow a balanced diet.

It Disrupts Your Body’s Natural Rhythm

Your blood pressure isn’t static. It follows a 24-hour rhythm, dipping at night and rising again in the morning. Inconsistent bedtimes, late-night eating or weekend “catch-up sleep” can throw that rhythm off. This irregular pattern, sometimes called “social jet lag,” can increase morning blood pressure and strain the cardiovascular system over time, explains Pratt. When melatonin levels stay low because of irregular sleep, blood vessels can’t dilate as easily, which can also contribute to higher blood pressure.

Poor Sleep Disrupts Metabolism and Raises Inflammation

Even when you technically log enough hours of zzz’s, poor-quality sleep can still take a toll. Nonrestorative sleep reduces insulin sensitivity and increases inflammation, both of which are associated with higher blood pressure. Fatigue combined with hormonal changes from poor sleep can also lead to cravings for salty, high-carb foods, adding another layer of stress for the cardiovascular system, explains Berger. Studies show that people with poor sleep quality tend to have more variable blood pressure readings and less of the natural nighttime dip that protects heart health.

How to Get Enough Sleep for Better Blood Pressure

Keep a Consistent Sleep-Wake Schedule

Going to bed and waking up around the same time each day, even on weekends, helps your body maintain a stable circadian rhythm. Try to keep variability within one hour to support the body’s natural nighttime dip in blood pressure, recommends Pratt. Research shows that regular sleep timing is linked to healthier morning blood pressure and reduced cardiovascular strain.

Limit Caffeine and Alcohol

Both caffeine and alcohol can raise adrenaline and cortisol levels, which constrict blood vessels and can make it harder to wind down at night. Alcohol also increases the production of renin, a hormone that raises blood volume, explains Pratt. Try skipping that late-afternoon latte or evening glass of wine to help your heart and nervous system relax before bed, recommends Berger.

Finish Dinner Early (and Keep It Balanced)

Large dinners, especially ones high in sodium, can keep digestion active and raise fluid retention overnight, interfering with your body’s ability to regulate blood pressure. Berger recommends finishing dinner at least two to three hours before bedtime and keeping meals balanced with lean protein, complex carbs and vegetables.

Get Morning Sunlight

Light cues help your body know when to be alert and when to rest. Exposure to natural sunlight within an hour of waking reinforces healthy melatonin production and lowers sympathetic nervous system activity, explains Pratt. Regular light exposure can make it easier to fall asleep and stay asleep, which can support more consistent blood pressure patterns.

Create a Calming Bedtime Routine

A relaxing nighttime ritual can help signal your body that it’s time to wind down. Pratt suggests taking a warm shower, doing your skin-care routine or reading, instead of scrolling on your phone. Gentle habits like these can support the parasympathetic (rest-and-digest) nervous system, which helps blood pressure naturally lower before sleep.

Our Expert Take

“Sleep is one of the most underrated tools for heart health,” says Pratt. Most adults need seven to nine hours of quality sleep each night to support healthy blood pressure. Regularly falling short keeps stress hormones high and blood vessels tense, making it harder for the cardiovascular system to recover.

To protect your heart, treat sleep like any other part of your wellness routine: keep a consistent bedtime, limit caffeine and alcohol, and get natural light exposure in the morning and evening. If you already have high blood pressure, monitor your readings and talk with a health care provider if you notice persistent changes or symptoms of poor sleep, such as loud snoring or morning fatigue.