Increasing scientific evidence indicates that social relationships have a significant effect on long term human health. Stressful or absent social relationships increases mortality rates and propensity of contracting chronic diseases, while supportive social relationships reduce these rates. Marriage is the dominant form of adult relationship across most human cultures, around 51 percent of adult Americans are married, and the nature of these relationships can have significant physiological impacts on long term health. Marriage acts as a physiological multiplier of the quality of partner relationships. While supportive, loving marriages decrease morbidity and mortality rates below those found non-married adults, stressful marriages increase these rates above the non-married control group.

Generally, marriage has a positive physiological effect on human health. Non-married individuals have significantly higher rates of mortality and illness than non-married individuals. These physiological benefits of marriage are not distributed equally among the genders though with only a 50 percent decrease in mortality among married women and a 250 percent decrease in mortality among married men. The association between marriage and positive health outcomes is argued to come from the broad base of support, both economic and social, that comes with marriage. However, marriage is not a universally positive multiplier of health. In fact, marital stress can have a significant negative and gender-biased physiological effects on long term health outcomes.

Marital stress effects the body through three major physiological channels: The cardiovascular, endocrine and immune systems. Like other forms of environmental stress, martial stress causes heightened blood pressure and heart rate. Interestingly when married subjects were asked to argue about an issue, whether personal or impersonal, women experienced heightened blood pressure and heart rate while men experienced little to no change in the cardiovascular state. However, men did show significant increases in blood pressure and heart rate while trying to influence their spouse especially in an aggressive manner.

Marital relationships also have substantial effects on the function of the endocrine system, the physiological pathways which produce hormones that regulate metabolism, growth, mood and a variety of other bodily functions. Among newlyweds, discussions of marital problems caused increased secretion of epinephrine, norepinephrine and cortisol, all stress hormones associated with the fight-or-flight response and which strain the body. Like with the cardiovascular system, marital stress during these discussions caused women to secrete higher relative levels of stress hormones than men. Partners who exhibit positive behaviors to each other during these conflict-resolution showed lower levels of stress hormones than those who exhibited neutral behaviors.

Like the cardiovascular and endocrine systems, marital stress causes significant decline in the immune systems of partners. Habitual hostile behavior and marital conflict is associated with a decline in natural killer cells and a decreased ability for the body to fight off adaptive herpes viruses. The older the test subjects the more pronounced the negative effect marital stress has on immune function. Following the differential pattern of gender and marital stress, women’s immune systems declined significantly more than men’s systems undergoing similar stress. Moreover, while female lymphocyte count decreased after marital conflict, male lymphocyte count increased. Marital stress on the immune system thus increases the likelihood for partners to contract disease and decrease their ability to repair physiological damage.

While marriage is the dominant form of adult relationship, in the United States it is dramatically declining as a cultural norm. According to the PEW Research Center, in 1960 72 percent of American adults were married compared to 2008 when only 51-52 percent of American adults. The decline in marriage isn’t uniform by class though. In 2008 64 percent of college graduates were married while only 48 percent of adults with only a high school degree were married. The last decade’s worth of research on the physiological effects of marriage raises questions about how the decline in marriage could create long term effects on public health. Will culturally normalized cohabitation replicate the social and economic support created by marriage in the modern system? If not, will adult Americans lose out on the physiological benefits of healthy marriage and the harms of stressful marriage? Will American society simply lose this physiological multiplier?

For more information see Robles et al. 2003 “The physiology of marriage: pathways to health” and related articles.