Washington, June 3 (ANI): Dishing with a friend does wonders for a woman's emotional state, but the scientific basis behind this phenomenon has been unknown to date.
A University of Michigan study has now revealed that feeling emotionally close to a friend increases levels of the hormone progesterone, which helps 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," said Stephanie Brown, lead author of the study.
Progesterone is a sex hormone that fluctuates with the menstrual cycle, which is also present in low levels in post-menopausal women and in men.
Earlier, scientists have 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.
In fact, the study also links these increases to a greater willingness to help other people, even at one's own expense.
"It's important to find the links between biological mechanisms and human social behaviour. These links may help us understand why people in close relationships are happier, healthier, and live longer than those who are socially isolated," said Brown.
Progesterone can be measured through simple saliva samples and may be related to oxytocin- a hormone linked to trust, pair bonding and maternal responsiveness in humans and other mammals.
In the current study, researchers examined the link between interpersonal closeness and salivary progesterone in 160 female college students.
At the start of the study, the researchers measured the levels of progesterone and of the stress hormone cortisol in the women's saliva, and obtained information about their menstrual cycles and whether they were using hormonal contraceptives or other hormonally active medications.
The women were randomly assigned to partners and asked to perform either a task designed to elicit feelings of emotional closeness or a task that was emotionally neutral.
It was found that the progesterone levels of women who had engaged in the emotionally neutral tasks tended to decline, while the progesterone levels of women who engaged in the task designed to elicit closeness either remained the same or increased.
The participants' cortisol levels did not change in a similar way.
After a week, the participants engaged in task designed to elicit closeness with their original partners again, while researchers examined links between progesterone levels and how likely participants said they would be to risk their life for their partner.
"During the first phase of the study, we found no evidence of a relationship between progesterone and willingness to sacrifice. But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner," said Brown.
She added: "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."
The study has been published in the journal Hormones and Behaviour. (ANI)