From the Dalai Lama’s claim that it is the “best meditation” to Benjamin Franklin’s insistence that it makes a person “healthy, wealthy, and wise,” a good night’s sleep has long been touted as the secret to a healthy life.
And the American Heart Association (AHA) agrees. In 2022, the AHA added sleep duration to Life’s Simple 8, their checklist for optimal heart health. This was on the basis of strong evidence from epidemiologic studies linking sleep duration to poor cardiometabolic outcomes, such as obesity, type 2 diabetes, and stroke.
But emerging research suggests that it’s time for cardiologists to consider more than just sleep duration.
“Lack of sleep has been long known to be associated with coronary heart disease,” said Martha Gulati, MD, the director of Preventive Cardiology in the Smidt Heart Institute at Cedars-Sinai, in Los Angeles.
Gulati emphasized that achieving adequate sleep (between 7 and 9 hours) has also been associated with healthy traits, such as better blood pressure, better cholesterol control, and healthy weight.
However, the number of hours a person sleeps each night just scratches the surface she said. Research has shown that consistency and preferred timing of sleep, known as sleep chronotype, are important as well.
In a 2023 UK-based study, middle-aged adults who considered themselves night owls — the evening sleep chronotype — had signs of potentially detrimental cardiac remodeling on cardiac magnetic resonance imaging compared with morning folks.
And the damage may start early. In a recent study in adolescents, shorter sleep duration was associated with adverse markers of left ventricular wall remodeling and liver fat accumulation suggesting a cumulative effect on health, according to the authors.
The MESA Sleep Ancillary study found that people with greater irregularity in sleep patterns — such as falling asleep at different times each night — had a higher coronary artery calcium burden than those with more regular sleep patterns.
Because sleep is associated with a range of cardiometabolic diseases, Julie Marcus, MD, a cardiologist at Weill Cornell Medicine/New York Presbyterian Hospital, New York City, said addressing poor sleep has become an important but underappreciated aspect of maintaining a healthy heart.
She added that patients also need to be aware that poor sleep can affect their health and what the various components of healthy sleep are.
“Beyond saying do you snore [or] stop breathing at night and do you sleep between 7 and 9 hours, there’s so much more to sleep that is important,” Marcus said.
Expanding the Definition of Sleep Health
Early this year, the AHA published an updated scientific statement that addresses multidimensional sleep health. This includes duration, timing, regularity, sleep-related daytime functioning, satisfaction, continuity — the ability to initiate and maintain sleep — and sleep architecture, or the amount and timing of the various sleep stages.
Marie-Pierre St-Onge, PhD, a sleep health researcher and lead author of the AHA statement, explained that it was developed to promote the breadth of new research.
“We want to let people know that sleep is more than just how long you sleep at night,” said St-Onge, who is the director of the Center of Excellence for Sleep and Circadian Research at Columbia University, New York City.
For example, she explained excessive daytime sleepiness has been associated with cardiovascular disease, coronary heart disease, stroke, and all-cause mortality. Similarly, sleep disturbances have been linked to hypertension, arterial stiffness, and coronary heart disease.
Understanding Poor Sleep’s Mechanism of Action
St-Onge emphasized that new research has also increased understanding around the associations between poor sleep and worsening cardiometabolic outcomes.
Her research has shown that sleep restriction increases oxidative stress in the lining of the arteries that could lead to endothelial dysfunction. Short sleep also impairs the body’s ability to counteract this oxidative stress.
“We see immune suppression from poor sleep duration and poor sleep quality,” St-Onge said.
In addition, we have found links between sleep regularity and eating patterns, St-Onge noted.
Gulati believes that the AHA statement represents an opportunity to raise awareness among patients, cardiologists, and clinical researchers about the importance of better understanding these causal effects of poor multidimensional sleep health.
“I think it is also a call to action to improve the assessment of sleep, particularly in research so we can rigorously assess these components,” Gulati said. “We need to know what interventions can improve components of sleep as well, and their effect on cardiovascular health. Those knowledge gaps need to be closed.”
Talking About Sleep Health
Those knowledge gaps are why the statement did not offer guidance for clinical approaches, but St-Onge emphasized the importance of educating and discussing this topic with patients now.
She recommended asking an open-ended question: ‘How’s your sleep?’ “That opens up a conversation for people to express exactly what’s bothering them with their sleep.”
For example, she said, “It may be they get plenty of hours of sleep, but they lie there awake for way too long, or they’re having a hard time falling asleep, or they get a lot of sleep, but they still wake up not feeling refreshed during the day.”
Starting the conversation — and documenting it in clinical notes — will be the first step to helping patients with poor sleep health, she said.
Marcus agreed that cardiologists should make time to discuss sleep health with patients, even though it can be more complicated than addressing cholesterol or blood pressure because “sleep is not a number.”
Still, she said that understanding a patient’s poor sleep health can also provide physicians with new modifiable risk factors for improving their cardiovascular health.
“Sleep is the next target,” Marcus said. “We know it impacts health, and it’s just a matter of how do we screen for it.”
Gulati reported financial relationships with Boehringer Ingelheim Pharmaceuticals, Medtronic, Merck & Co., New Amsterdam, and Zoll.
St-Onge and Marcus reported no relevant financial relationships.