People who go to sleep at different times or get varied amounts of rest from one night to the next may be more apt to develop hardening in the arteries, a new study suggests.

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Staying up too late a few nights a week could be doing a number on your heart.Acharaporn Kamornboonyarush/Getty Images

Need another reason to set a regular bedtime and stick to it? A new study suggests that too much variation in the timing and amount of sleep you get may increase the likelihood of developing a major risk factor for heart attacks and strokes.

The study focused on the connection between sleep habits and atherosclerosis, an accumulation of fatty plaque inside artery walls that makes blood vessels stiffer and narrower over time, reducing blood flow and oxygen distribution throughout the body. These fatty deposits can also form blood clots that could block the artery, leading to a heart attack or stroke.

Uneven Bedtimes and Sleep Duration Correlated to Higher Likelihood of Atherosclerosis

To determine the relationship between sleep regularity and blood vessel health, scientists asked more than 2,000 middle-aged and older adults to wear wrist devices to detect when they were asleep and awake and to fill out sleep diaries for one week. Participants also completed an in-home sleep study to get more detailed information on how their bodies functioned during sleep, including assessments of their heart rate and breathing patterns.

Compared with people who consistently got similar amounts of sleep each night, participants with at least two hours of variation in sleep duration during the week were up to 75 percent more likely to show signs of atherosclerosis, researchers reported in the Journal of the American Heart Association.

Adults with bedtimes that varied by 90 minutes or more over the course of a week were also more than 40 percent more likely to show signs of atherosclerosis than people with the most consistent bedtimes.

“This study is one of the first investigations to provide evidence of a connection between irregular sleep duration and irregular sleep timing and atherosclerosis,” says lead study author

Kelsie Full, PhD, MPH, an assistant professor of medicine in the division of epidemiology at Vanderbilt University Medical Center in Nashville, Tennessee.

This connection persisted even after researchers accounted for several other factors that might independently influence atherosclerosis risk such as smoking, drinking, age, sex, race and ethnicity, exercise habits, obesity, high blood pressure, and work schedules.

The study wasn’t a controlled experiment designed to prove whether specific sleep habits might directly cause atherosclerosis, and it also didn’t assess whether hardening in the arteries resulted in events like heart attacks or strokes. Another drawback of the study is that scientists only measured sleep and atherosclerosis at a single point in time.

Good Sleep Hygiene Is Essential for Heart Health

Even so, the findings underscore the importance of creating good sleep habits, Dr. Full says. “Maintaining regular sleep schedules and decreasing variability in sleep is an easily adjustable lifestyle behavior that can not only help improve sleep, but also help reduce cardiovascular risk for aging adults,” Full says.

Constant shifts in bedtimes and wake times can disrupt the body’s circadian rhythms, or the body’s internal biological clock that naturally kicks into gear during the day and winds down at night, says Marie-Pierre St-Onge, PhD, director of the Center of Excellence for Sleep and Circadian Research at Columbia University Irving Medical Center in New York City.

“These circadian rhythms regulate cardiovascular functions like heart rate and blood pressure,” says Dr. St-Onge, who wasn’t involved in the new study. “Disruptions and disturbances in these rhythms can cause chronic inflammation, impact glucose metabolism, and cause alterations in immune functions, all of which can contribute to atherosclerosis.”

Recognizing the importance of sleep for cardiovascular health, the American Heart Association (AHA) last year added sleep to its key recommendations for a heart-healthy lifestyle. Most adults need seven to nine hours of sleep a night to reduce the risk of heart disease and a wide range of other chronic health issues, the AHA advises.

Tips for Better Sleep Habits

There are several things you can do to develop what’s known as good sleep hygiene, or a routine that helps you consistently sleep on a regular schedule and get enough rest, says José Ordovás, PhD, a sleep researcher and professor of nutrition and genomics at Tufts University in Boston, who wasn’t involved in the new study.

Dr. Ordovás suggests:

• Regular Bedtimes Try to go to bed and wake up at the same time every day, even on weekends. This can help regulate the body’s internal clock and make it easier to fall asleep and wake up at the desired times.
• Relaxing Routines Engage in activities that help you relax and wind down before bedtime, such as taking a warm bath, reading a book, or listening to calming music. Avoid stimulating activities, such as watching TV or using electronic devices, in the hours leading up to bedtime.
• Comfortable Bedroom Create a sleep-conducive environment by keeping the bedroom dark, cool, and quiet. Invest in a comfortable mattress and pillows that support good sleep posture.
• Watch What You Drink Limit caffeine and alcohol intake — and avoid drinking either of these within a few hours of bedtime because they can disrupt sleep.
• Regular Exercise Regular physical activity can improve sleep quality and reduce the risk of heart disease.
• Reduce Stress Find healthy ways to manage stress, such as practicing relaxation techniques or engaging in enjoyable hobbies or activities.