(Relaxnews)
Bonding with your girlfriends might be just what the doctor ordered, according to a study by researchers at the University of Michigan and published in the June issue of the journal Hormones and Behavior.
In it, researchers say that the sex hormone progesterone, which is produced by women of childbearing age but which is also present in post-menopausal women and men, is increased when feeling emotionally close to a friend, heightening feelings of well-being and reducing anxiety and stress.
Higher levels of progesterone have been shown to increase the desire to bond with others, but the current study is the first to show that bonding with others increases actual levels of the hormone. The study also links these increases to willingness to help others, even if it involves self-sacrifice.
"It's important to find the links between biological mechanisms and human social behavior," said Stephanie Brown, of the University of Michigan's Institute for Social Research and assistant professor of internal medicine at the University of Michigan Medical School, who led the study. "These links may help us understand why people in close relationships are happier, healthier, and live longer than those who are socially isolated."
In the study, Brown's team examined the link between interpersonal closeness and progesterone and stress hormone levels measured from saliva samples from 160 female college students.
They found that progesterone levels increased or remained the same in women who engaged in tasks designed to encourage bonding and closeness. When the women performed emotionally neutral tasks, their progesterone levels declined and their stress hormone levels remained unchanged. The researchers also examined links between progesterone levels and whether participants would risk their life for a companion.
"During the first phase of the study, we found no evidence of a relationship between progesterone and willingness to sacrifice," Brown said. "But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner."
Brown said their findings support an evolutionary theory of altruism that says that hormonally determined social bonds cause people to suppress self-interest for another's welfare, like when caring for children, or the sick or elderly. The results are consistent with the proven health benefits of social contact, she said.
"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.
AFP Relax News, 18/07/2011
