Although long assumed, it turns out friendships are good for your health. Researchers at the University of Michigan found that social bonding can increase levels of the hormone progesterone, a neuroendocrine chemical associated with a number of body processes, including reducing anxiety and stress.
Progesterone
Progesterone is a steroid hormone secreted by the ovaries. Its function is to prepare the uterus for the implantation of a fertilized ovum and to maintain pregnancy. Progesterone is produced in the corpus luteum of the ovaries of menstruating women and is synthesized by the placenta. It is also found in the adrenals and stored in fat tissue.
Progesterone serves a number of functions in the body including countering the effects of estrogen body by "downregulating" estrogen receptors. It also:
- reduces anxiety and increases sleepiness
- helps to build and maintain bone
- slows the digestive process
- promotes appetite and fat storage (important in pregnancy)
(Project Aware Online: Association of Women for the Advancement of Research and Education)
The word "progesterone" is often used as the kitchen sink term to describe all progestogens. Progesterone and bioidentical progesterone do not however, have a similar molecular make-up to the commonly used synthetic "progestin" found in birth control pills and conventional hormone replacement therapy such as Prempro.
Social Bonding Elevates Progesterone, Lowers Anxiety & Stress
Researchers at the University of Michigan Institute for Social Research (ISR) found that interpersonal closeness increases levels of progesterone in women, ("Feeling Close to Friend Increases Progesterone, Boosts Well-being and Reduces Anxiety & Stress," ScienceDaily, June 3, 2009).
The study randomly assigned women to a partner and a task that was either emotionally neutral, proofreading a botany script together, or a task designed to elicit emotional closeness, a computerized cooperative card game.
Results indicate that progesterone levels dropped in women engaged in the emotionally neutral task but remained the same or increased in women assigned to the task designed to evoke emotional closeness. Neither task affected levels of cortisol, a hormone associated with stress.
"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.
Hormone Progesterone Linked to Altruistic, Self-less Behaviors
When the subjects returned a week later and played the computerized card game with their original partners they were asked how likely 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," Brown said. "But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner."
Brown suggests that these findings are consistent with the new evolutionary theory of altruism, that social bonding has a hormonal basis which allows people to suppress their own self-interests to promote the well-being of others, such as when they take care of children or help a friend or family member in need.
Scientists have long known that the hormone oxytocin is linked to trust and bonding in animals and humans. Oxytocin can only be measured however, through an invasive spinal tap, while progesterone levels can be easily measured through saliva testing. Because both of these hormones are associated with social bonding and feelings of attachment, scientists believe progesterone and oxytocin may be related.
Footnotes:
"Feeling Close To A Friend Increases Progesterone, Boosts Well-being And Reduces Anxiety And Stress." ScienceDaily. Retrieved June 8, 2009.
Additional Resources:
Oxytocin: The Direct Route to Altruism?
Laura Owens - Laura Owens has a B.S. in Psychology from Rollins College & U of FL. She is a freelance writer with expertise in motivation & wellness.
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