Study: Insomnia Linked to Increased Risk of Heart Attack, Especially for Women

People who experience insomnia may have a greater risk of having a heart attack, compared to those who don’t have the sleep disorder, new research shows. Women with insomnia seem to be at an even greater risk, as are people with both diabetes and insomnia.

The findings come from a new study, presented earlier this month at the American College of Cardiology's Annual Scientific Session Together With the World Congress of Cardiology. The research was also published in the journal Clinical Cardiology in February.

“Insomnia is the most common sleep disorder, but in many ways it’s no longer just an illness, it’s more of a life choice. We just don’t prioritize sleep as much as we should,” first study author Yomna E. Dean, a medical student at Alexandria University in Alexandria, Egypt, said in a news release. “Our study showed that people with insomnia are more likely to have a heart attack regardless of age, and heart attacks occurred more often in women with insomnia.”

It’s estimated that about 30% of adults experience insomnia—or trouble falling asleep, staying asleep, or getting good quality sleep—and the condition often affects more women than men. Past research has also linked insomnia to other conditions like cardiovascular and metabolic diseases, and the new findings suggest that insomnia should be considered a risk factor for heart attack.

“Based on our pooled data, insomnia should be considered a risk factor for developing a heart attack,” Dean said in the news release, “and we need to do a better job of educating people about how dangerous [lack of good sleep] can be.”

Here’s what to know about the link between insomnia and heart attack risk, and how to better prioritize healthier sleep habits.

Insomnia and Risk of Heart Attack

For the study, Dean and her research team sought to assess the potential of insomnia being a risk factor for myocardial infarction (MI), known more commonly as a heart attack. To do that, they pooled data from nine studies—originating from the U.S., U.K., Norway, Germany, Taiwan and China—which included data from more than one million adults.

Of those people—who were an average age of 52 years old—almost 154,000 people had insomnia, which was characterized by having any of the three following symptoms:

• Difficulty falling asleep
• Difficulty staying asleep
• Waking early and not being able to go back to sleep

All told, 2,406 people with insomnia had a heart attack during an average of nine years of follow-up; meanwhile, just over 12,000 people in the non-insomnia group had a heart attack during that same time period. Ultimately, people with insomnia were 69% more likely to have a heart attack, compared to those who did not have insomnia.

“Not surprisingly, people with insomnia who also had high blood pressure, cholesterol or diabetes had an even higher risk of having a heart attack than those who didn’t,” Dean said in the news release. “People with diabetes who also have insomnia had a twofold likelihood of having a heart attack.”

The specific amount of sleep people reported mattered too: People who said they typically got five or fewer hours of sleep each night were more likely to experience heart attack, compared to people who got six to eight hours of sleep. Heart attack risk was also elevated for people who got nine or more hours of sleep, suggesting that both too little and too much sleep can be detrimental to heart health.

How Might Sleep Affect Heart Health?

“There is no question that for many years as cardiologists we have recognized the link between sleep disorders and cardiovascular illness,” said Dennis Finkielstein, MD, associate chair of cardiology at Lenox Hill Hospital, who was not involved in the new study.

“If we think about insomnia and restful sleep, it’s physiology,” Dr. Finkielstein told Health. “It is a period of restoration for the body and if that’s removed with insomnia, you can imagine that it can invoke a fight or flight response throughout the night. Over the long run, I’m not surprised that it can lead to a heart attack.”

Another potential mechanism is the lack of sleep’s impact on cortisol levels—widely known as the body’s stress hormone. “Sleep deprivation, a consequence of insomnia, puts the body under stress, triggering cortisol release which could accelerate atherosclerosis,” said Dean. Atherosclerosis—known more commonly as plaque buildup in the arteries—can lead to blockages which can cause heart attack among other cardiovascular complications.

Still, certain limitations to the study suggest that much more research is needed to prove a link between insomnia and heart health risks.

“There is a lot of interest in sleep health with relation to cardiovascular disease,” said Anais Hausvater, MD, a cardiologist at NYU Langone Health. “The study is hypothesis-generating, but I think there have to be more studies to see how much the risk is attributed to insomnia, and how much to other mechanisms.”

Dr. Hausvater pointed out that measured insomnia through surveys, or self-reported data, which is less trustworthy due to human error. “There’s a bias in that measurement because it relies on people to recall how much they have slept, which is quite difficult for some people,” said Dr. Hausvater. “It would be valuable to have studies that use technology to measure sleep to objectively measure levels of insomnia in relation to a heart attack.”

How to Prioritize Sleep Quality and Quantity

According to Dean, people should prioritize their sleep; getting seven to eight hours of quality sleep each night is preferred.

Getting the proper amount of sleep hinges on your sleep hygiene, or the environment and daily tasks that prime you for sleep throughout the day. “The room should be dark, quiet and on the cooler side, and put away devices,” Dean said in the news release. “Do something that is calming to wind down, and if you have tried all these things and still can’t sleep or are sleeping less than five hours, talk with your doctor.”

Additionally, Dr. Finkielstein recommended that people don’t nap throughout the day, which can affect sleep at night, and to only use your bed for sleep—that can signal to the brain that when you’re in bed it’s time to sleep. “Don’t eat or drink alcohol late at night,” added Dr. Finkielstein, “[and] make sure you’re physically active during the day.”

If your sleep hygiene is up to par, you may want to consider speaking to a healthcare professional who may be able to point you to a specialist. “I would say if you have chronic insomnia, which is one month or more of non-restful and non-lengthy sleep, it may be time to see a primary care physician who may refer someone to a sleep medicine specialist,” Dr. Finkielstein said.

It’s also worth noting that just because someone may experience insomnia does not mean they are definitively going to have a heart attack—many other factors can be at play.

“If the rest of your lifestyle is healthy, meaning you’re active and you make time to de-stress, and you have insomnia, you will do better than someone with other factors like smoking, not exercising, eating poorly, and stress in life,” Dr. Finkielstein said. “A bigger and better second study would be to tease apart the associated factors.”

“The basics are the basics for a reason,” added Dr. Finkielstein. “Good sleep is one of the basics. Add to that exercise and eating right and taking time to destress. When all of that isn’t going well, it’s not surprising that the outcome may be worse.”