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The study, published in February, collected data from over 2,000 U.S. adults aged 45 and 84 years old. For seven days, participants wore a device that collected data about their sleep patterns and underwent a handful of cardiovascular assessments.

The researchers looked at a range of factors, including coronary artery calcium (which helps measure how much plaque buildup there is in your arteries), carotid intima-media thickness (which diagnoses the extent of the buildup), and the ankle-brachial index (a test that compares the blood pressure in the upper and lower limbs). 

The researchers cross-examined both sets of data and found that sleep irregularity—particularly when it comes to sleep duration, or how many hours of sleep you get a night—was associated with several risk factors for arteriosclerosis, a type of disease characterized by a narrowing of the arteries.

More specifically, the results showed that variations in sleep duration of more than 2 hours a night within the same week were more likely to have higher levels of coronary artery calcium and abnormal ankle-brachial indices. 

This study suggests that when it comes to sleep, maintaining a consistent bedtime and wake time is just as important as how many hours of sleep you get overall. And this isn’t the first time irregular sleep habits have been connected to poor health outcomes.

A 2018 study1 showed that more irregular sleep patterns were linked to an increased risk of obesity, hypertension, blood sugar issues, and heart attacks. The same study showed that irregular sleepers are more likely to report chronically high stress levels and depression.

This study is preliminary, but it’s the first ever to link irregular sleep habits with atherosclerosis. And considering that this disease is an underlying factor in more than 50% of deaths in the Western world2, it’s a pretty big deal. 

This study suggests that to promote optimal health, we shouldn’t deviate our bedtime by more than 2 hours within a week. This gives us some wiggle room, but not much. It means that if we go to bed at 10 p.m. on the weekdays, we shouldn’t stay out past midnight on the weekend, or go to bed before 8 p.m. if we’re particularly tired one evening. 

Maintaining consistent sleep patterns takes a little intention and planning, and nobody will ever be perfect. That said, crafting a solid nighttime routine is a great way to get in the habit of going to bed at the same time each night and help ourselves wind down at the end of a long day. Here are some ideas to start with: 

1. Wind down with skincare: Establishing a skincare routine—one that’s complete with removing makeup and SPF, cleansing, treating skin issues, and moisturizing—can be a great way to step away from the screen and wind down for bed. Here’s how to create a nighttime skincare routine from start to finish. 
2. Get morning sun: Your sleep-wake cycle, also known as your internal clock or circadian rhythm, is modulated by the sun and other types of light exposure. “I have learned to pay a lot of attention to the role that light plays in regulating my circadian rhythm,” holistic psychiatrist Ellen Vora, M.D., writes for mindbodygreen. “I make a point of getting actual sunshine into my actual eyeballs as early in the morning as possible,” she continues. This also means avoiding light late at night, which can suppress melatonin production and keep you up past your bedtime. 
3. Try a magnesium supplement: Magnesium is known as nature’s relaxation mineral, and it’s a great choice for a non-hormonal sleep aid. And many of us need more of this important mineral, as it’s estimated that 43% of U.S. adults3 currently fail to meet their daily needs through diet alone. Here are the 14 best magnesium supplements of 2023—some of which are specifically designed to help you fall asleep.
4. Move your body (gently): A late-evening workout can spike your cortisol and keep you awake, but a nighttime yoga sequence can do just the opposite. Try this nighttime yoga sequence to prepare your body for an on-time snooze.
5. Be mindful of caffeine: Caffeine affects us all differently, but if you’re a slower caffeine metabolizer, having a coffee later in the day can keep you up well beyond your bedtime. If you’re looking for consistency with your sleep, you may want to stop drinking coffee or tea at the same time every day as well. Learn more with this caffeine guide.