The Power of Peers

Who Influences Your Health?

Do birds of a feather really flock together? The science says yes. People do tend to choose friends who are similar to them. You also become more like your friends over time. And that can influence your health.

Many behaviors spread socially. Examples include how much you exercise, how much alcohol you drink, whether you smoke, and what foods you eat.

Scientists are still trying to untangle why that is. Studies have found that activity in certain brain areas changes when other people are around. That can affect what you choose to do.

But this work also suggests that you can harness the power of social relationships to gain healthier habits—and motivate others to do the same.

Social Influence

“People care about what others think across all different age groups—and that influences how much they value different ideas and behaviors,” says Dr. Emily Falk at the University of Pennsylvania. She studies how social networks affect decision making. This is called social, or peer, influence.

Teens are especially responsive to peer influence. That’s because their brains undergo changes that make them highly attuned to social situations. At the same time, the reward system in the teen brain becomes extra sensitive.

The reward system is a brain circuit that causes feelings of pleasure. It’s activated by things we enjoy, like eating good food. It’s also activated by social rewards, like getting a compliment.

And teens are just learning to navigate the social world. Understanding other people’s values and being influenced by them are important parts of socializing. Being influenced on things like clothing choices and musical taste can help teens learn to fit in and make friends. But taking part in risky behaviors, like drinking alcohol or smoking, can lead to health or legal consequences.

“Research shows that even just having another peer around can change the reward response in the brain and also the risk-taking tendencies of teenagers,” says Falk. Her team studies how peers affect teens’ driving behaviors and smoking decisions.

Some people seem to be more easily influenced than others, too. They may be more sensitive to feeling included or excluded by others. Or they may be more sensitive to social signals, like the tone of someone’s voice or their body language.

Dr. Mary Heitzeg’s team at the University of Michigan is doing research to better understand how a person’s biology and reactions to social situations affect whether they develop substance use or mental health problems later in life.

Using brain scans, the team is looking at how teens’ brains respond to being socially included or excluded. They’re also looking at how the brain’s reward system responds to different situations.

Heitzeg’s team is part of a large 10-year effort, called the ABCD Study, to understand the factors that influence teens’ health and risk behavior in the long term. Factors can include families, friends, schools, neighborhoods, and communities.

“Adolescence is such a risky period,” says Heitzeg. “That’s when sexual initiation happens, initiation and escalation of substance use happens, as well as other types of risky and delinquent behaviors, like risky driving.”

But it’s also a time that peer influence can help teens thrive if it gets them more involved with their community or helps them learn behaviors to get along with others, like how to cooperate or be empathetic.

Peer Quality, Not Quantity

Positive and negative peer influences can affect more than just your behavior. They can also change the way you feel.

Studies show that, in general, the more friends you have and the more time you spend with them, the happier you are. Friends give you people to share your feelings with, to get new perspectives from, or to just do fun activities with.

But it’s the quality of those friendships—not quantity—that really makes the difference. Quality of friendships has been linked to higher life satisfaction and better mental health.

“We’ve all experienced letting a friendship go because it didn’t feel great,” says Dr. Rebecca Schwartz-Mette of the University of Maine. Her lab studies how peer relationships affect the emotional development of children and teens.

Friendships you feel you want to let go of may be low quality. They might be fraught with conflict, criticism, and aggression. For youth, low quality friendships are linked to poor academic performance and behavioral issues.

High quality friendships provide understanding, support, and validation of your self-worth. These types of friendships are more stable and are more satisfying.

Spending time with friends can be especially helpful for people with anxiety or depression. However, Schwartz-Mette’s studies have shown that depression can also be worsened by certain friendship qualities. One is called co-rumination.

“Co-rumination is basically when people get together and talk excessively about everything that’s going wrong and how bad they feel,” she explains. “With that person, they feel understood, validated, and that this person is emotionally close to them. But they get more depressed because they’re focusing their attention on negative things.”

Research suggests that it may help to refocus such friendships. Talk about both positive and negative things in your day. Look for healthy activities to get out and do together, like going for a walk. Encourage each other to keep up healthy habits like physical activity, healthy eating, and getting a good night’s sleep.

“Noticing that our behavior is influenced by other people, we can be intentional and try to focus on the people who are doing the things we want to get into ourselves,” Falk explains. “Sharing your healthy habits with other people could make a real difference to somebody else.” And to yourself.

Parents can help guide their kids toward more positive social experiences, too (see the Wise Choices box for tips). But everyone can benefit from high quality friendships that help you nurture healthy habits.