man sleeping in bed

NHLBI-funded research helps shape a key heart-health checklist

For years, the community of researchers that studies sleep has tried to raise awareness about the growing link between poor sleep and heart disease. Now, after much effort, they can mark progress toward recognizing that all-important connection.

For the first time, the American Heart Association has added sleep to the key components it advises Americans use to measure cardiovascular health. The new list, now called Life’s Essential 8, replaces a shorter list of metrics called Life’s Simple 7, created in 2010.

Adequate sleep now joins a familiar list of targets to track while building a healthy heart: a healthy diet, ample physical activity, smoking cessation, a healthy weight, and healthy levels of blood lipids, blood sugars, and blood pressure.

It is a change influenced by extensive evidence provided by NHLBI-funded scientists on the connection between sleep and cardiovascular health over the years.

“We are delighted to see the American Heart Association incorporate evidence, much of it from NHLBI-supported research, showing that sleep health is foundational to human health, including heart health,” said David Goff, M.D., Ph.D., director of NHLBI’s Division of Cardiovascular Diseases. Noting that NHLBI partners with AHA to promote heart-health research and lifestyles, Goff added, “The evolution of AHA’s Life’s Simple 7 into the Essential 8 holds great promise for advancing our shared mission to turn discovery into better cardiovascular health for all.”

Marishka Brown, Ph.D., director of the NHLBI’s National Center on Sleep Disorders Research, agrees. She calls the new sleep metric “a testament to the strength of the research funded by NHLBI.”

“This action taken by the AHA clearly shows that sleep is equally as important to cardiovascular and overall health as other factors such as exercise and nutrition,” Brown said. The release of the Essential 8, she said, will hopefully bring more awareness of the connection between poor sleep and health, more informed research on the topic, and ultimately, new sleep-based interventions that could reduce the risk of heart disease.

The AHA change also will encourage researchers to investigate what aspects of sleep contribute to cardiovascular health and how untreated sleep disorders contribute to cardiovascular disease, Brown added.

The spotlight on sleep comes at a pivotal time: Millions of Americans are not getting enough of it, and many are unaware how this can affect their cardiovascular health. For example, studies link poor sleep to a greater risk of obesity, diabetes, and high blood pressure — all risk factors for heart disease, which is the leading cause of death in the United States and worldwide. Although the exact mechanisms linking poor sleep to heart disease continue to be investigated, optimizing sleep may improve heart health and ultimately save lives, researchers say.

Life’s Essential 8 is the outgrowth of two decades of work and more than 2,400 scientific papers related to cardiovascular health.

“It was a bit of a long time coming, but I’m thrilled to see sleep added,” said Susan Redline, M.D., M.P.H., a professor of sleep medicine at Harvard Medical School and director of the Sleep Medicine Epidemiology Program at Brigham and Women’s Hospital. An NHLBI grantee, her research has been demonstrating the link between poor sleep and cardiovascular risk factors as well as clinical heart disease across multiple populations, and she has been pushing for its wider inclusion as a health metric for improving population health. “Because minority populations are at increased risk for both sleep problems and cardiovascular disease, the new recommendations may help reduce health disparities,” Redline said.

So why did the AHA update the metric now?

“It takes time to build the evidence base,” explained Marie-Pierre St-Onge, Ph.D., a sleep researcher at Columbia University Irving Medical Center in New York who studies the relationship between sleep and cardiometabolic health. “And you really can’t make recommendations if you don’t have strong evidence.”

Spurred on by the research, the evidence linking sleep problems to heart disease had been growing gradually for years. But during the last decade, large, diverse NHLBI cohorts like MESA, CARDIA, ARIC, CHS and the Jackson Heart Study began including sleep metrics in their health assessments. Now, sleep research and its relationship to cardiovascular disease has exploded, St-Onge said.

Redline and St-Onge suggested that a recent study they helped co-author may have given the AHA one of the critical pieces of evidence it needed to include sleep in the Essential 8. Presented as an abstract in 2020 in Circulation, one of AHA’s premier journals, the study focused on NHLBI’s MESA cohort and included 1,920 ethnically diverse middle-aged and older adults, a population considered at high risk for developing heart disease. The study showed that participants who got adequate amounts of sleep (seven to nine hours of sleep per night) in addition to meeting Life’s Simple 7 guidelines, experienced up to 61% lower odds of having heart disease. It concluded that adding sleep duration to the Life’s Simple 7 metric would create a stronger tool for predicting heart disease risk.

Now that AHA has made that change, Redline and St-Onge said there’s yet more work to be done. In particular, they call for wider recognition of other aspects of sleep beyond duration. These include measures such as sleep consistency and quality, which also impact cardiovascular health.

“In the next few years, I think we’ll be able to make the case for the inclusion of a more nuanced set of sleep targets that individuals could strive for,” Redline said. “Not only do you need adequate sleep duration, but you need adequate and consistent and quality sleep.”

In the coming years, scientists will continue to explore the biological underpinnings, including genetics and blood markers, behind poor sleep and heart disease. Already, for example, they have linked poor sleep to atherosclerosis, or plaque buildup in the heart’s arteries, through various inflammatory mechanisms. And sleep problems have been associated with poor blood pressure control because of its damaging effects on the blood vessels. A better understanding of these mechanisms, researchers say, could lead to helpful interventions, such as wearable devices or specialized mobile apps designed to reduce irregular sleep, as well as new medicine.

As research continues, experts encourage people to pay more attention to their sleep health and consult their healthcare providers if they have sleep problems, and they encourage clinicians to ask their patients about sleep.

“Thanks to AHA’s Essential 8, sleep has been elevated in the broader conversation of cardiovascular health,” notes NCSDR’s Brown, “and that’s a wonderful thing. Our overall health will benefit in the long run.”