Marriage and other long-term relationships have health perks, but men and women don't benefit equally

Is marriage good for your health? In general, research suggests yes. Married people live longer, have better access to health care, enjoy a more satisfying sex life, experience less stress, live a healthier lifestyle, and have lower rates of heart disease, diabetes, and depression compared to their single counterparts.

The list of health perks conferred by marriage is so long, in fact, that the U.S. Department of Health and Human Services has made it a centerpiece of its two-year-old, $5 million national media campaign to promote wedded bliss.

But there's a catch—men and women don't get the same or equal benefits from a legally sanctioned pairing. A man's sex life is likely to improve more than a woman's after getting married, for instance, while a woman's risk for depression tends to decrease more than her partner's when she's in a long-term relationship.

And in reality, getting hitched may not be strictly necessary. Women and men can reap some health benefits just by living together, or even by being in a stable long-term relationship, research suggests. Experts believe that same-sex couples, many of whom don't even have the option to get married, also score health gains, though almost all research so far has focused only on heterosexual relationships.

"I don't think it's necessarily a matter of the marriage license; it's a matter of the level of social support and mutual attachment," says John Gallacher, PhD, a researcher at the Cardiff University School of Medicine in Wales, who recently published a paper on the health benefits of relationships in a BMJ journal.

We interviewed experts and sifted through the scientific research to determine which sex fares better in each of these eight categories.

Life span. Marriage offers the ultimate health benefit: a longer life. Compared to their unwed counterparts, married people have longer average life spans and are drastically less likely to die at an early age.

The link between marriage and longevity is much stronger among husbands than wives, however. A 2007 study that looked at death rates among European people over age 40 found that the rate was twice as high in unmarried men as in married men. The disparity in death rates was far more modest between unmarried and married women.

Marriage is especially good at warding off fatal accidents, violence, and other semi-avoidable calamities, which are more common in younger people, says Michael Murphy, PhD, a professor of demography at the London School of Economics and the lead author of the 2007 study. But regardless of age, men's life spans appear to benefit more from marriage than women's. Advantage: Men.

Disease. One reason marriage may prolong life is that it appears to lower a person's risk of serious disease. Rates of diabetes, heart disease, Alzheimer's, lung disease, and other chronic ailments are all lower in married people than in unmarried people. (Notably, cancer is not on the list.)

For most diseases, the decrease in risk associated with marriage is roughly the same for men as for women. The exception—and it's a big one—is heart disease, the No. 1 killer in the U.S. each year. While married men are three times less likely to die from heart disease than men who have never tied the knot, marriage only halves the risk of cardiac death for women, according to a 2009 study. Advantage: Men.

Vices. The disproportionate heart benefits that men reap from marriage may be partly explained by the fact that bachelors tend to lead less healthy lifestyles than unmarried women, and are more apt to smoke, drink too much, and indulge in other vices. (In other words, men have more room for improvement after they get married.)

A 2006 study that tracked the substance-use patterns of thousands of young people before and after marriage found that men abruptly scale back their binge drinking and marijuana use when they get married. Women also binge drink less after they get married (or even after they start living with a boyfriend), but they smoke marijuana just as often after marriage as they did before.

Although relationship status appears to have less of an effect on cigarette smoking (perhaps because nicotine is so addictive), notable gender differences exist here as well. A woman who marries a smoker is more likely to start smoking herself, but the opposite doesn't hold: If their brides smoke, men are no more likely to start or resume smoking themselves, a 2005 study found.

Simply put, women may be a better influence on men than vice versa. Wives tend to be the more emotionally supportive partner and are more likely to encourage their husbands to refrain from drinking or smoking, says Hui Liu, an assistant professor of sociology at Michigan State University in East Lansing. Advantage: Men.

Depression. Although people love to complain that their significant others are driving them crazy, companionship actually tends to be good for mental health—especially for women. This is particularly true when it comes to depression, which is roughly twice as common in women.

"Depression is a very female expression of psychological distress," says Robin Simon, PhD, a professor of sociology at Wake Forest University in Winston-Salem, N.C. "The benefit of marriage shows up in women in lower levels of depression."

Marriage also appears to be a stabilizing force in women with bipolar disorder. Married bipolar women have fewer and milder depressive episodes than their never-married counterparts, but the same trend is not found in bipolar men.

Living with a partner seems to be just as beneficial to a woman's mental health as marriage. A 2005 study of women over 50 found that cohabiting reduces the risk of mental health problems just as much as getting hitched. Advantage: Women.

Stress. Contrary to popular belief, men tend to get stressed out more easily than women. Lab experiments have shown that when given a stressful task, men exhibit greater spikes in the stress hormone cortisol than women.

Fortunately for men, being in a romantic relationship—not just marriage—may curb their stress response. A 2010 experiment found that paired-off men had smaller spikes in cortisol levels than single men after taking part in a competitive game, whereas single and spoken-for ladies had comparable cortisol increases. Advantage: Men.

Weight. A marriage license or a long-term relationship won't buy you a clean bill of health, of course. One area where marriage appears to actually harm health is the waistline. "Historically there's been this idea that marriage makes people healthy, particularly men," says Susan Averett, PhD, a professor of economics at Lafayette College in Easton, Pa. "That may be the case, but not with respect to BMI." (BMI refers to body mass index, a simple ratio of height to weight.)

While both men and women in long-term relationships tend to gain weight (probably because they've implicitly agreed to let themselves go), women appear to gain a bit more weight on average after marriage than men—even if they don't have children.

But the catch is that more men than women cross over into the dangerous categories of overweight and obese following marriage. This could be because women are more likely than men to be underweight going into marriage, so they can afford the extra pounds more than their groom can. Another strike against men could be that they scale back their exercise regimen more so than women after getting married.

Although unmarried couples living together also gain weight, and women gain more than men, the weight gain is less pronounced than in married couples. "It's a little different because you might think of yourself as still on the market," Averett says. Advantage: Women.

Sex. TV images of swinging bachelors and bachelorettes might say otherwise, but being in a solid relationship actually tends to be good for your sex life (at least for the first decade or two). Married and cohabiting couples both have more sex than people who are single or dating, and married people in particular report more satisfying sex lives than their counterparts who are dating or shacking up.

Still, where sex is concerned, marriage appears to be a better deal for men. In a landmark national sex survey conducted in the 1990s, 49% of married men said they were "extremely" emotionally satisfied with their sex life, compared to just 33% of men who were unmarried or not living with a partner. By contrast, only 42% of married women were extremely satisfied with their sex lives, compared to 31% of women who didn't live with a partner.

Women's sex lives aren't as fulfilling as men's in marriage "because they often have resentment in inequities in domestic duties that still exist, [and] they feel they don't get the appreciation they deserve," says Pepper Schwartz, PhD, a professor of sociology at the University of Washington in Seattle. Advantage: Men.

Financial stability. Married people are more financially stable than their single counterparts. And even though more women than ever before have college degrees and are the main breadwinners in their household, marriage still tends to mean a bigger step up for women than it is for men. "Even today, women still benefit from marriage in terms of economics," Liu says. "For men, it's mainly from the social, psychological factors."

While worrying less about money certainly helps reduce stress and anxiety, financial stability also impacts health in a more concrete way, via access to health care. Marriage is associated with a hearty increase in the likelihood of having health insurance for both sexes, but it is associated with much greater gain for men. However, the percentages of single and married men who are insured still lag behind those of single and married women. Advantage: Tie.

Our matchup puts men ahead by a slight margin—but women shouldn't be dismayed. "[Although] there used to be a lot of literature that women get a raw deal in marriage, there's been a bunch of research that says, 'No, they're really happy, and they think they're getting as good a deal,' " Schwartz says.

And there's reason to believe that women might actually start to get just as good a deal from relationships as men do. Many of the gender differences we found arise from one sex having healthier habits than the other to begin with, or taking on the brunt of the work in and outside of the home. But a 2010 survey by the Pew Research Center found that, in the last several decades, people are getting married at an older age and to those with more matched socioeconomic and educational backgrounds, which could dissolve some of those gender differences.

And yet, even though the nature of relationships and marriage is changing with the times, the impact of relationships on health measures such as life span has remained largely steady. The health gender gap might take some time to catch up to these social trends, Liu says. "I think over time we may see men and women get similar benefits from marriage," she says. "The gender roles have changed with more women going to work."