- Too much variation in your bedtime, wake-up time, and sleep duration may increase your heart disease risk, according to one study.
- Researchers found that people with the greatest irregularities in sleep patterns were more likely to have a build-up of plaque in their arteries.
- Doctors explain steps you can take to improve your sleep quality.
Maintaining a consistent sleep routine that consists of going to bed at the same time every night and waking up at the same time every morning can go far towards supporting your overall health. Now, scientists say there’s also a strong link between irregular sleep and heart disease, with a study suggesting that too much inconsistency in your sleep patterns may increase your risk.
The study, which was published in the Journal of the American Heart Association, analyzed data from more than 2,000 adults from across the country with an average age of 69. For three years, the study participants wore a device around their wrist that tracked when they were asleep and awake, and they also filled out a sleep diary for seven straight days. Participants also did a one-night, in-home sleep study to look at their breathing, sleep stages, waking after they went to sleep, and heart rate.
Meet the experts: Jag Sunderram, M.D., the interim chief in the Division of Pulmonary and Critical Care Medicine at the Rutgers Robert Wood Johnson Medical School; Kelsie M. Full, Ph.D., M.P.H., an assistant professor of medicine at Vanderbilt University Medical Center; Holly S. Andersen, M.D., an attending cardiologist and an associate professor of clinical medicine at the New York-Presbyterian Hospital, Weill Cornell Medical Center; Thomas Boyden, M.D., the medical director for preventive cardiology and cardiac rehabilitation at Corewell Health in Grand Rapids, MI.
Once they had the data, the researchers looked at irregularities and variations in participants’ sleep habits. They found that the largest variation in total number of hours slept per night was more than two hours in one week, while the biggest irregularity in bedtime was more than 90 minutes in one week.
The researchers conducted a slew of tests to look for buildup of plaque in the arteries (a condition known as atherosclerosis, which can cause a heart attack, stroke, or blood clot) and found that people with irregular sleep patterns were more likely to have higher levels of plaque compared to those with more consistent sleep schedules. Specifically, those whose sleep durations varied by more than two hours in a week were 1.4 times more likely to have high coronary artery calcium scores (which measure the amount of calcified plaque in the arteries, the main underlying cause of cardiovascular events such as heart attacks and strokes) compared to those who had more consistent sleep durations.
People with irregular sleep durations that varied by more than two hours a week were also 1.12 times more likely to have carotid plaque (plaque in arteries that deliver blood to your brain). Those who had more irregular sleep timing (i.e. they mixed up when they went to bed and when they woke up) were 1.43 times more likely to have high coronary artery plaque compared to those who had sleep timing that varied by 30 minutes or less within a week.
The researchers concluded that regular sleep patterns could be a “modifiable” factor in helping people reduce their risk of atherosclerosis. But…why? Here’s what you need to know.
The possible impact of sleep patterns on heart disease risk
It’s important to note that heart disease—including atherosclerosis—is a complicated condition that can have many causes. At the same time, this particular study found a link between irregular sleep and atherosclerosis, but didn’t show that having irregular sleep patterns actually causes atherosclerosis. “Irregular sleep may also indicate irregular lifestyle habits such as irregular timing of food, poor food habits, and diet that were not taken into consideration,” pointed out Jag Sunderram, M.D., the interim chief in the Division of Pulmonary and Critical Care Medicine at the Rutgers Robert Wood Johnson Medical School.
“It is likely that the link is multifactorial and sleep may play an important role of many factors,” said lead study author Kelsie M. Full, Ph.D., M.P.H., an assistant professor of medicine at Vanderbilt University Medical Center.
Still, this isn’t the first study to suggest that sleep issues may be a top risk factor for heart disease.
“These findings support a growing body of research that shows the health benefits of regular sleep patterns—going to bed at the same time and getting out of bed at the same time,” said Holly S. Andersen, M.D., an attending cardiologist and an associate professor of clinical medicine at the New York-Presbyterian Hospital, Weill Cornell Medical Center. “The body likes a schedule.”
Older research in the Journal of the American College of Cardiology analyzed data from nearly 2,000 men and women and also found that irregular sleep patterns increased the risk of heart attack, stroke, and other cardiovascular events. At the start of the study, no participants had cardiovascular disease. After five years, 111 had some cardiovascular issue, including heart attack, stroke and even death from a cardiac-related issue. The researchers found that people with irregular sleep schedules were nearly twice as likely to develop cardiovascular disease as those with more regular sleep patterns.
Research has also connected inconsistent sleep with poor heart health. The Centers for Disease Control and Prevention (CDC) specifically warns that adults who sleep less than the recommended seven hours a night are more likely to have health problems, including heart attack.
Researchers are still sorting out the reason for this, but there seem to be a few factors at play. “Chronic fatigue from sleep deprivation may lead to decreased physical activity, poor dietary choices, overeating due to low energy and potentially weight gain,” said Thomas Boyden, M.D., the medical director for preventive cardiology and cardiac rehabilitation at Corewell Health in Grand Rapids, MI. Those can lead to a slew of health conditions that can then influence your heart health, he said.
One is that lack of sleep and inconsistent sleep can keep your blood pressure up for a longer period of time (your blood pressure goes down when you have normal sleep). High blood pressure is one of the leading causes of heart disease and stroke.
Research has also found that getting good sleep may help some people with type 2 diabetes improve blood sugar management and lower the risk of damage to the blood vessels that can come from a build-up of sugar in the blood. Lack of sleep and irregular sleep can also lead to unhealthy weight gain and obesity, which raises the risk of heart disease.
Dr. Andersen said that it’s “possible” that something else may explain the link between irregular sleep patterns and a higher risk of heart disease, like unhealthy lifestyle choices, but it’s unlikely. “There is much evidence to support that going to bed and getting up at the same time can be a very healthy practice,” she said. “Sleep is made up of different stages including REM or dream sleep. Interfering with these patterns can trigger unhealthy responses in the body for the heart and for memory and cognition.”
How to improve your sleep to protect your heart
Again, it’s unlikely that irregular sleep patterns alone will cause atherosclerosis. However, if you can, experts say it’s not the worst idea to try to maintain a consistent sleep schedule, even on the weekends. “Sleeping in on the weekends may feel good and may reduce stress for many of us—but a lifestyle that supports a daily routine with good sleep is superior,” Dr. Andersen said. Full agreed. “In general, avoiding extreme variations is the key,” she said. What’s more, Dr. Sunderram added that if you’re constantly sleeping in on the weekends, it may be a sign of chronic sleep deprivation during the week that merits correcting.
All that said, if you really love sleeping in on weekends, the data doesn’t definitively say that you need to give it up for the sake of your heart health. “Potentially, sleeping in for more than 60 minutes than what someone is normally doing during the week could increase risk,” said Jim Liu, M.D., a cardiologist at The Ohio State University Wexner Medical Center. “However, I wouldn’t be too concerned about that right now. …There’s a lot that goes into irregular sleep duration and this would have to be studied more before making any firm conclusions about sleep duration regularity and cardiovascular health.”
Keep in mind too, that it’s not a good idea to stay up late during the week and then hope to make up for it on the weekends. “Sleeping in on the weekends may not overcome the deleterious effects of sleep irregularity and decreased sleep duration during the week,” Dr. Boyden said. “The long-term effects of the sleep irregularity and decreased sleep duration will likely continue to have cardiovascular implications even in the setting of better sleep on the weekends.”
In general, it’s good to try to be somewhat consistent with your sleep patterns. “This is provocative in that, as the authors point out, it identifies a readily modifiable lifestyle parameter that could impact one’s cardiovascular risks,” said Devin Kehl, M.D., a non-invasive cardiologist at Providence Saint John’s Health Center in Santa Monica, Calif.
If you’re not sleeping as well as you’d like and it’s leading to sleep irregularity, Dr. Boyden recommended working on your sleep hygiene. According to the CDC, that can include:
- Sticking to a regular sleep schedule
- Getting enough natural light, especially earlier in the day
- Getting enough physical activity during the day
- Avoiding artificial light, especially within a few hours of bedtime
- Avoiding eating or drinking within a few hours of bedtime
- Keeping your bedroom cool, dark, and quiet
“Sleep is essential to our overall health and well-being,” Full said. “It’s important to do what you can to create a healthy and realistic sleep routine that works for you. If you are still having problems with your sleep after this, you should try talking to your healthcare provider.”
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