Research & Discovery > Getting Sleepy? Check Your Heart Health

Getting Sleepy? Check Your Heart Health

By Alison Caldwell, Ph.D.

Virend Somers, M.D., Ph.D., thinks you should probably be sleeping in later.

“Using an alarm clock, by definition, means that you haven’t had enough sleep,” says Dr. Somers, Alice Sheets Marriott Professor at Mayo Clinic. “When you wake up artificially, your body has not yet decided to wake up. The best way to sleep is to be able to wake up in the morning refreshed, without an alarm clock.”

While that may be aspirational, it does speak to the cardiologist and sleep expert’s conviction regarding the benefits of sleep.

Sleep and Heart Health

At Mayo Clinic, Dr. Somers leads a team studying the relationship between sleep disorders and cardiovascular disease, including the impacts of conditions such as sleep apnea and excessive daytime sleepiness (EDS). Thanks to support from Sleep Number, his research has uncovered a strong relationship between how sleepy someone is during the daytime and their risk of heart problems.

In a study published in 2021, Dr. Somers and his team found that nearly 1 in 5 people out of 10,000 participants reported experiencing EDS. In addition, people who said they felt “overly sleepy” often or always during the daytime were at 2 ½ times greater risk of dying due to heart issues when compared to those who did not feel so sleepy. This was completely independent of any other sleep issues or disorders.

“We have only recently begun to really understand how important daytime sleepiness is,” Dr. Somers says. “Usually the focus is on problems that affect nighttime sleep, but EDS is its own issue with its own implications.”

Uncovering the Link

Dr. Somers has been in the sleep game for long enough to see how far the research has come. “I became interested in sleep because of some interesting nighttime blood pressure findings during my Ph.D. studies. At that time, there was very little being done in this area,” he says. “Sleep occupies a third of our lives, but the research was limited to just a few centers and was focused on neurology and pulmonology. I wanted to understand how sleep might be affecting heart health, and that was the road less traveled.”

A year after his initial study, Dr. Somers examined the relationship between nervous system activity in people with obstructive sleep apnea, excessive daytime sleepiness, and heart health, finding that patients with sleep apnea who had clinically observed EDS had higher diastolic blood pressure and increased sympathetic nervous system activity compared to those who did not have EDS, which may be linked with greater cardiovascular morbidity.

“Our research is finding this risk is independent of whether someone is experiencing other sleep problems,” says Dr. Somers. “How sleepy someone feels during times when they are supposed to be awake seems to be associated with significant health risks.”

His research continues to dissect the relationship between sleep and cardiovascular disease, seeking to better understand who is most at risk. In a 2023 study, his team examined a cohort of nearly 15,000 patients with obstructive sleep apnea and found that women who had the condition and experienced excessive daytime sleepiness were at higher risk of dying prematurely compared to others. In men, EDS did not increase their mortality risk, though both men and women with sleep apnea and EDS were at higher risk of developing diabetes.

“This means that when dealing with sleep disorders, sleep apnea or even just heart disease, it’s important for clinicians to ask their patients — especially their female patients — not only about their sleep habits, but also about how sleepy they feel during the day,” says Dr. Somers.

How sleepy someone feels during times when they are supposed to be awake seems to be associated with significant health risks.
— Virend Somers, M.D., Ph.D.

Seeking Clarity for Future Treatments

Even as he assesses his patients for their sleepiness and heart health risk, Dr. Somers says there are still many unanswered questions about this relationship: Do daytime sleepiness and heart disease develop in parallel? Does one cause the other? Are the mechanisms of sleepiness causing damage to our blood vessels, resulting in cardiovascular disease?

Going forward, his team plans to dig into the physiological and biochemical underpinnings of this relationship in the hope of better understanding what factors are at play in excessive sleepiness and heart disease. Understanding these interactions will be the key to addressing heart health risk for these patients and ultimately identifying treatment targets.

“This is the beauty of mechanistic research,” he says. “We’re focused not just on the phenomenon, but also understanding the underlying mechanism, because once we know the mechanism, we’ll have some ideas on how we might intervene to treat it.”

This research has been conducted in collaboration with Sleep Number. Through a corporate partnership, Sleep Number and Mayo Clinic are working together to deepen knowledge on the relationship between sleep, sleep disorders and cardiovascular health. Sleep Number also supports Mayo Clinic research in other areas of sleep research, including studies on the prevalence of disordered sleep among Somali patients and the relationship between disrupted sleep and markers of aging.