You’ve probably heard, ad infinitum, that you need seven to nine hours of sleep a night to feel rested, and stay healthy. But you may not know that consistency around the hours you sleep each night is just as important as how much sleep you’re actually getting.

A new study published in the Journal of the American Heart Association, found that irregular sleep patterns, like making up for lost weeknight sleep on weekends, can hurt your heart health. Study authors found that getting inconsistent amounts of sleep was associated with a higher risk of plaque buildup in the arteries (atherosclerosis). According to the Mayo Clinic, this causes the arteries to narrow, blocking blood flow to the heart. It can also lead to burst arteries and dangerous blood clots anywhere in the body.

“Most people are aware that having a regular bedtime and getting a sufficient amount of sleep promote good health. This study adds important information by highlighting how inconsistent sleep patterns can impact cardiovascular health,” says Pranav Patel, MD, of Inspira Medical Group Cardiology.

The study included 2,000 people of varying races and ethnicities. It found that those with highly irregular sleep schedules, like overnight and rotating shift workers, were the ones most likely to have significant atherosclerosis and other markers for heart disease.

You don’t have to be a shift worker to experience these effects, however. “Upsetting the sleep-wake cycle even by a few hours has been associated with increased cardiovascular events,” says cardiologist John Higgins, MD, of UTHealth Houston McGovern Medical School. He specifies that schedule alterations like changing the clock to daylight savings time (ahem!) or changing time zones during travel can cause these effects. He also cautions that you can’t make up for those all-important seven to nine hours by sleep-binging on weekends after skimping on sleep during the week.

According to study researchers, disruptions to circadian rhythm are to blame. “Irregular sleep patterns have been shown to cause chronic inflammation, increase blood pressure, and alter glucose metabolism, which in turn increases insulin resistance. All of these factors are known to contribute to the development of coronary artery disease,” Dr. Patel explains.

Circadian rhythm disruption can affect multiple systems in your body, from hormonal balance to skin health. “Not having a regular bedtime increases the production of stress hormones which, in turn, increases blood pressure and thickens the blood, making heart attack or stroke more likely,” adds Dr. Patel.

How to set a consistent sleep schedule 

Some professions don’t lend themselves to optimum sleep hygiene (think healthcare workers, flight attendants, first responders). Most people can, however, improve the consistency of their current sleep routine. Dr. Higgins says the first step is reaching out to your healthcare professional for guidance if you snore or wake up feeling unrested. “It’s important to uncover underlying issues like sleep apnea, which can increase blood pressure,” he explains.

You can also use these tips from the Mayo Clinic:

1. Stay consistent: Pick a time for sleep that you can stick to seven days a week. That doesn’t mean you can never go clubbing till 3:00 a.m. again. You don’t have to be perfect all the time, just most of the time.

2. Know when to start over: If you can’t fall asleep within 20 minutes of getting into bed, leave your bedroom to do something relaxing, like reading. Go back to bed when you feel sleepy. This solidifies that your bed is a place for sleeping, not tossing and turning.

3. Keep dinner moderate: Don’t go to bed hungry or overly full. Eating heavy meals too close to bedtime may cause sleep disruptions like indigestion and acid reflux. Instead, center your dinner around foods that are known to make us sleepy.

4. Avoid stimulants: Nix the caffeine, alcohol, and nicotine for at least a few hours before bed. All of these substances have a fairly substantial half-life, which is the time it takes for your body to rid itself of half of it. The half-life of caffeine, for instance, is four to six hours. That means an after-dinner espresso may keep you buzzing hours later when you go to bed. Similarly, the half-life of alcohol is four to five hours, while nicotine has a half-life of two hours.

5. Give your electronics, including your phone, a curfew: Put them down for at least an hour or two before sleep. Instead, read a (physical) book, take a bath, or chat with your family or roommates.

6. Keep your bedroom cool and dark.The ideal temp is 60 to 67 degrees Fahrenheit. And if you don’t have blackout curtains, invest in a sleep mask.

7. Block out sounds: If outside noises keep you awake (hi, roommates!), use a white noise machine or app to mask it.

8. Avoid daytime naps, if you can: Snoozing for too long mid-day, or too late in the day, can make it harder to get your Zzzzs at bedtime.

9. Get regular exercise: Research shows that working out gives people deeper sleep. (Bonus points if it comes with fresh air.) Just be sure to finish up any intense sweat sessions at least three to four hours before bedtime.

10. Try to put your worries and anxiety on hold:Meditate before bed, or write down the things that are worrying you, so that it’s easier to let them go.

—reviewed by Jennifer Logan, MD, MPH