Sponsor banner

What are friends for? To lower your stress levels

Study finds familiar partners and friendships reduce cortisol levels for a lifetime

Access to this AJC content is brought to you by our sponsor, Wellstar

Keep smiling, keep shining, knowing you are lowering your cortisol levels. That’s what friends are for.

Researchers at the Beckman Institute for Advanced Science and Technology evaluated how a person’s age and familiarity with others affects a conversation, reviewing the interaction’s overall effectiveness and stress responses generated as a result.

Led by postdoctoral researchers Michelle Rodrigues and Si On Yoon, the team examined two hypotheses for the study, which focused on people who identify as female. First, the tend-and-befriend hypothesis, which contrasts with the traditionally masculine “fight-or-flight” dichotomy.

“Women have evolved an alternative mechanism in response to stress,” Rodrigues, who is currently an assistant professor in the Department of Social and Cultural Sciences at Marquette University, said in a Beckman press release. “In order to deal with stress, women can befriend female peers.”

The team also tested the socio-emotional selectivity hypothesis, which suggests a social “pruning” as people get older and pursue more intimate, higher-quality circles of friends.

The introduction of age as a variable is new in the field and stems from an interdisciplinary Beckman collaboration.

“I was working with several different groups in several different disciplines, coming from the perspective of studying friendship but having previously done research on adolescent girls, but not older women,” Rodrigues said.

She combined forces with Yoon, who was studying the cognitive mechanisms of natural conversation across the lifespan, including healthy younger and older adults. The team merged their theories into a single question: Across women’s lifespans, how are the tendencies to “tend and befriend” as well as socially select reflected in their communication?

They tested a pool of 32 women: 16 “older adults” ages 62-79, and 16 “younger adults” ages 18-25. Each participant was paired either with a friend (a “familiar” conversation partner) or a stranger (“unfamiliar”) and put through a series of conversation challenges.

Each participant had to instruct her partner to arrange a set of tangrams in an order that only the former could see. The catch? Because tangram shapes are abstract, their appearances can be difficult to describe.

“You could look at one and say, ‘This looks like a dog.’ Or, you could say, ‘This looks like a triangle, with a stop sign, and a bicycle wheel,’” Rodrigues explained. Partners who achieved the desired tangram arrangement in fewer words were considered more efficient.

The researchers found the younger adults communicated more efficiently with familiar partners but less efficiently with unfamiliar partners. The older adults, however, demonstrated conversational dexterity, quickly describing the abstract tangrams to friends and strangers alike.

“Even though older adults choose to spend more time with people who matter to them, it’s clear that they have the social skills to interact with unfamiliar people if and when they choose to,” Rodrigues said.

Rodrigues’ team also measured the stress hormone cortisol to quantify and compare participants’ stress levels during the tests.

“When you experience something stressful, if you have a stress response system that’s working as it should, the result is an elevated amount of cortisol, our primary stress hormone, which then tells our bodies to release glucose into our bloodstreams,” she said. “That’s reflected in our saliva about 15 to 20 minutes after we experience it. If we see a rise in salivary cortisol from an individual’s baseline levels, that indicates that they are more stressed than they were at the time of the earlier measurements.”

Across both age groups, those working with familiar partners had consistently lower cortisol levels than those working with strangers.

“A lot of the research on the tend-and-befriend hypothesis has only focused on young women, so it’s great to have these results that pull that out to the end of life. We can see that friendship has that same effect throughout the lifespan. Familiar partners and friendship buffer stress, and that’s preserved with age,” Rodrigues said.

The full study, titled “What are friends for? The impact of friendship on communicative efficiency and cortisol response during collaborative problem solving among younger and older women,” was published in the Journal of Women and Aging in May.

For more content like this, sign up for the Pulse newsletter here.

About the Author