Why does dishing with a girlfriend do wonders for a woman’s mood?
A U-M study has identified a likely reason: Feeling emotionally close to a friend increases levels of the hormone progesterone, helping to boost well-being and reduce anxiety and stress.
“This study establishes progesterone as a likely part of the neuroendocrine basis of social bonding in humans,” says researcher Stephanie Brown, lead author of an article reporting the study findings, published in the June 2009 issue of the peer-reviewed journal Hormones and Behavior.
A sex hormone that fluctuates with the menstrual cycle, progesterone also is present in low levels in post-menopausal women and in men. Earlier research has shown that higher levels of progesterone increase the desire to bond with others, but the current study is the first to show that bonding with others increases levels of progesterone. The study also links these increases to a greater willingness to help other people, even at our own expense.
“It’s important to find the links between biological mechanisms and human social behavior,” says Brown, a faculty associate at the Institute for Social Research and an assistant professor of internal medicine at the Medical School. She also is affiliated with the Ann Arbor Veterans Affairs Hospital. “These links may help us understand why people in close relationships are happier, healthier and live longer than those who are socially isolated.”
According to Brown, the findings are consistent with a new evolutionary theory of altruism which argues that the hormonal basis of social bonds enables people to suppress self-interest when necessary in order to promote the well-being of another person, as when taking care of children or helping ailing family members or friends.
The results also help explain why social contact has well-documented health benefits — a relationship first identified nearly 20 years ago by U-M sociologist James House.
“Many of the hormones involved in bonding and helping behavior lead to reductions in stress and anxiety in both humans and other animals. Now we see that higher levels of progesterone may be part of the underlying physiological basis for these effects,” Brown said.
