By Belinda Luscombe
February 25, 2016

Can a lousy marriage actually break your heart? Or a good marriage mend it? Increasingly, researchers are finding that cardiac health and the happiness of our relationships are dance partners. Researchers have long known that married people tend to live longer and be healthier than their single peers. Some of the reasons for that are not mysterious: married people are more likely to have someone who’s keeping an eye on them, who notices when they’re unwell, who can pick up their medications or take them to the doctor.

But new research suggests that the benefit isn’t simply having someone around to call 911 in an emergency–the quality of the marriage makes a difference too. A 2015 University of Michigan study followed more than 1,300 couples over six years and found that bad marriages can affect heart health. When a wife is stressed, the study found, her husband’s systolic blood pressure tended to go up. If both spouses thought the marriage wasn’t going well, the husband’s blood pressure spiked even more. The effect was different for wives: their blood-pressure readings were higher if the relationship was going badly. But if their husbands were reporting more stress, the wives’ blood pressure tended to drop.

Why the inverse relationship? “Husbands tend to rely on spouses for support, which may not be provided when wives are experiencing high levels of stress,” says the report. Wives, on the other hand, find support from a wider network of sources, say the researchers, so if their spouse is unable to offer them succor, they have more places to turn.

Some researchers are also looking at marriages that are neither deliriously happy nor unhappy but somewhere in between. A recent study out of Brigham Young University found that people whose marriages were ambivalent–with a significant amount of negative interaction as well as some positive–consistently had higher blood pressure than those who said their marriages were very satisfying. Worse, those nasty exchanges erased the cardiovascular bump that the positive exchanges gave them.

So while a good marriage is good for hearts, it takes work. Another study found that both husbands and wives who fought more had thicker carotid arteries. It’s not clear which came first, the harsh words or the thickening, but it certainly brings new meaning to the term hard-hearted.

Heart-attack recovery

Married people survive heart attacks more often than single people, and a new study has noted another bonus: they bounce back better too.

University of Pennsylvania researchers found that spouses who had major cardiac surgery had better functional recovery within two years than patients who were divorced, separated or widowed. That means they were more able to get dressed, bathe or go to the bathroom on their own. In fact, those who were no longer married were about 40% more likely to die or develop a new functional disability in the first two years postsurgery than those with a spouse at home. (There were not enough never-married people in the study to make an assessment on them.)

The researchers are not sure whether the results are because less-healthy people are more likely to be unmarried or because spouses make a big difference in rehabilitation. Either way, they say hospitals should consider marital status when helping people plan their post-heart-attack life.

Contact us at editors@time.com.

This appears in the March 07, 2016 issue of TIME.

SPONSORED FINANCIAL CONTENT

Read More From TIME

EDIT POST