American culture places a high premium on romantic love. In fact, relationship woes—or the lack thereof—are among the top reasons people seek therapy. And while romance can be a meaningful part of life, the benefits of friendships should not be overlooked. Psychological research suggests that stable, healthy friendships are crucial for our well-being and longevity.

People who have friends and close confidants are more satisfied with their lives and less likely to suffer from depression (Choi, K. W., et al., The American Journal of Psychiatry, Vol. 177, No. 10, 2020). They’re also less likely to die from all causes, including heart problems and a range of chronic diseases (Holt-Lunstad, J., et al., PLOS Medicine, Vol. 7, No. 7, 2010; Steptoe, A., et al., PNAS, Vol. 110, No. 15, 2013).

“On the other hand, when people are low in social connection—because of isolation, loneliness, or poor-quality relationships—they face an increased risk of premature death,” said Julianne Holt-Lunstad, PhD, a professor of psychology and neuroscience at Brigham Young University who studies how relationships affect the body and brain.

Fortunately, research also suggests that friendships can be made and maintained at any age, relationships with friends can strengthen or stand in for romantic relationships, and even minimal social interactions can be powerful.

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“Friendship is something we really need to understand. There’s been this preoccupation with romantic relationships, but many of our close relationships are with friends,” said Thalia Wheatley, PhD, a professor in the Department of Psychological and Brain Sciences at Dartmouth College who studies social connectivity. “So how do they impact our health?”

Psychological research from around the world shows that having social connections is one of the most reliable predictors of a long, healthy, and satisfying life.

A review of 38 studies found that adult friendships, especially high-quality ones that provide social support and companionship, significantly predict well-being and can protect against mental health issues such as depression and anxiety—and those benefits persist across the life span (Pezirkianidis, C., et al., Frontiers in Psychology, Vol. 14, 2023; Blieszner, R., et al., Innovation in Aging, Vol. 3, No. 1, 2019). People with no friends or poor-quality friendships are twice as likely to die prematurely, according to Holt-Lunstad’s meta-analysis of more than 308,000 people—a risk factor even greater than the effects of smoking 20 cigarettes per day (PLOS Medicine, Vol. 7, No. 7, 2010).

“In the face of life’s challenges, having a close friend to turn to seems to be a buffer or protective factor against some of the negative outcomes we might otherwise see,” said Catherine Bagwell, PhD, a professor of psychology at Davidson College in North Carolina.

Friendships protect us in part by changing the way we respond to stress. Blood pressure reactivity is lower when people talk to a supportive friend rather than a friend whom they feel ambivalent about (Holt-Lunstad, J., et al., Annals of Behavioral Medicine, Vol. 33, No. 3, 2007). Participants who have a friend by their side while completing a tough task have less heart rate reactivity than those working alone (Kamarck, T. W., et al., Psychosomatic Medicine, Vol. 52, No. 1, 1990). In one study, people even judged a hill to be less steep when they were accompanied by a friend (Schnall, S., et al., Journal of Experimental Social Psychology, Vol. 44, No. 5, 2008).

Scientists studying friendship have even found similar brain activity among friends in regions responsible for a range of functions, including motivation, reward, identity, and sensory processing (Güroğlu, B., Child Development Perspectives, Vol. 16, No. 2, 2022). When Wheatley and her colleagues collected fMRI data on people in a social network, closer friends had more similar brain activity when watching a series of video clips (Nature Communications, Vol. 9, 2018). In another study, currently under review, she and her colleagues can even begin to predict whether first-year MBA students at Dartmouth will later become friends based solely on their neural patterns.

“The big surprise here is that the similarities are all over the brain, including regions that control how we direct our attention, how we think about things, and even what we’re looking at,” Wheatley said.

On the other side of the coin, research has shown that loneliness—among people who lack quality friendships, romantic partnerships, or other relationships—increases our risk for heart attack, stroke, and premature death, according to a longitudinal study of nearly 480,000 U.K. residents (Hakulinen, C., et al., Heart, Vol. 104, No. 18, 2018). A meta-analysis by Holt-Lunstad estimates that loneliness increases the risk of early death as much as 26% (Perspectives on Psychological Science, Vol. 10, No. 2, 2015).

Those findings have prompted leading health organizations, including the American Heart Association and the National Academies of Sciences, Engineering, and Medicine (NASEM), to warn the public against the dangers of isolation, particularly for older adults (Cené, C. W., et al., Journal of the American Heart Association, Vol. 11, No. 16, 2022; Social Isolation and Loneliness in Older Adults: Opportunities for the Health Care System, NASEM, 2020).

Despite the risks, Americans are getting lonelier. In 2021, 12% of U.S. adults said they did not have any close friends, up from 3% in 1990 (“The State of American Friendship: Change, Challenges, and Loss,” Survey Center on American Life, 2021). That decline began well before the COVID-19 pandemic, with companionship and social engagement among friends, family, and others decreasing steadily over the past two decades (Kannan, V. D., & Veazie, P. J., SSM – Population Health, Vol. 21, 2023).

Social disconnection, which is rising across age groups, appears to have worsened after 2012, when smartphones and social media became virtually ubiquitous. An international study of high school students found that between 2012 and 2018, school loneliness increased in 36 of 37 countries (Twenge, J. M., et al., Journal of Adolescence, Vol. 93, No. 1, 2021).

“There were significant downward trends in social contact even before the pandemic,” Holt-Lunstad said. “What’s remarkable about that is that ‘getting back to normal’ is not going to be enough—because it wasn’t looking good before.”

The COVID-19 pandemic likely exacerbated an existing trend toward social isolation—and it also provided a natural way for scientists to measure the effects of that shift. Bagwell and psychologist Karen Kochel, PhD, of the University of Richmond, found that college students with less social support from their friends during the first year of the pandemic also had more problems with anxiety, depression, and academic adjustment (Emerging Adulthood, Vol. 10, No. 5, 2022).

“For these students, their relationships with their friends and peers were quite significant in predicting how they were doing, both academically and in terms of their emotional adjustment,” Bagwell said.

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Having a close friend or confidant is undeniably good for us, but psychologists have found that interactions with acquaintances—and even strangers—can also give our mental health a boost. A casual relationship with the operator of a hot dog stand in Toronto helped Gillian Sandstrom, PhD, feel grounded and connected while pursuing her master’s degree. The relationship also inspired Sandstrom, now a senior lecturer in psychology at the University of Sussex, to start studying “weak” social ties.

These connections with acquaintances—a work friend you bump into once a week, the pet store employee who remembers your cat—can be surprisingly sustaining. Sandstrom’s research has found that people who have more weak-tie interactions are happier than those who have fewer and that people tend to be happier on days when they have more than their average number of weak-tie interactions (Personality and Social Psychology Bulletin, Vol. 40, No. 7, 2014). She also encourages talking to strangers and has shown that repeated practice can make doing so easier and more enjoyable (Journal of Experimental Social Psychology, Vol. 102, 2022).

“These minimal social interactions give us something important that we missed during the pandemic: novelty,” Sandstrom said. “We learn surprising things when we have unplanned encounters and conversations with people,” a benefit that people tend to underestimate (Atir, S., et al., PNAS, Vol. 119, No. 34, 2022).

People often avoid conversations with strangers, assuming they will be awkward or shallow, but research suggests those worries may be overblown. Psychologist Nicholas Epley, PhD, of the University of Chicago, and his colleagues have found that conversations with strangers tend to be less awkward, more enjoyable, and more connecting than people expect. To their own surprise, people also tend to prefer having deep conversations with strangers over shallow ones (Journal of Personality and Social Psychology, Vol. 122, No. 3, 2022).

Sandstrom has some advice for connecting with strangers: Tap into your curiosity. Ask someone what they’re reading, for example, or why they’re wearing airplane earrings. Another tip: Comment on the shared situation. While standing in the checkout line at a mini-mart, Sandstrom once connected with a fellow customer over the store’s unusual mishmash of Halloween and Christmas decorations.

“You’re in the same place at the same time as the other person, so there’s always something in common,” she said.

We tend to see friendship and romance as separate entities, but the two may have more in common than we realize. Psychological research points to qualities such as chemistry, intimacy, and warmth as key building blocks of close, stable friendships (Ledbetter, A. M., et al., Personal Relationships, Vol. 14, No. 2, 2007; Campbell, K., et al., The Social Science Journal, Vol. 52, No. 2, 2015).

Regular interactions with acquaintances—the local coffee barista, for example—make people happier.

“When we view behaviors that create intimacy—being vulnerable, buying gifts, taking someone out on a date—as only appropriate for a romantic relationship, we end up limiting the potential of our friendships,” said psychologist Marisa G. Franco, PhD, an assistant clinical professor at the University of Maryland and author of Platonic, a book about making and keeping friends. “Many of us could really benefit from blurring the lines between the two.”

Conversely, romantic relationships may be more fulfilling if they look more like friendships. An analysis of nearly 8,000 respondents to the British Household Panel Survey showed that life satisfaction was about twice as high among people who said their spouse was also their best friend (“How’s Life at Home? New Evidence on Marriage and the Set Point for Happiness,” NBER Working Paper No. 20794, 2014).

Research also suggests a symbiosis between romantic and platonic relationships, Franco said, suggesting that one can benefit the other. For example, marital conflict can trigger unhealthy changes in cortisol levels, but that harm is buffered when spouses feel they have adequate social support outside the marriage (Keneski, E., et al., Social Psychological and Personality Science, Vol. 9, No. 8, 2017). Other research indicates that women who have social support are more resilient to stress that occurs within a marriage (Abbas, J., et al., Journal of Affective Disorders, Vol. 244, 2019).

There’s also reason to believe that skills developed in friendships can be carried forward into healthier romantic relationships, particularly among teens and young adults.

“Friendships are the first relationships in life that we get to freely choose,” said Melanie Dirks, PhD, a professor of psychology at McGill University in Montreal who studies peer relationships in children, adolescents, and young adults. “Because of that, they present a really important opportunity to learn how to navigate challenging interpersonal situations before we enter relationships as adults.”

For example, self-disclosure between friends—sharing thoughts and feelings—helps young adults build empathy for others, practice seeking and providing social support, and even solidify their identities, said Rebecca Schwartz-Mette, PhD, an associate professor of clinical psychology and director of the Peer Relations Lab at the University of Maine who studies friendship in children, adolescents, and young adults.

Many young adults in the United States are juggling life transitions, stress, and developmental challenges—and friends are typically their main sources of social support, which makes them critical for psychologists to study and understand, said Dirks.

She has studied the types of challenges that tend to arise in young adult friendships, finding that they undergo strain for one of three reasons: needs are in conflict (for example: there’s one spot on a sports team that both friends want); a transgression occurs (for example: one friend reveals private information about the other); or friends have trouble exchanging support (for example: one has a problem with alcohol use, but the other doesn’t know how to help) (Journal of Research on Adolescence, Vol. 31, No. 2, 2021).

In childhood and adolescence, high-quality friendships can protect kids from mental health issues—such as anxiety and depression—that might otherwise result from social challenges, including being bullied (Bayer, J. K., et al., Child and Adolescent Mental Health, Vol. 23, No. 4, 2018). But there are also conditions where mental health struggles can harm friendships. Schwartz-Mette and her colleagues have found that between friends, excessive self-disclosure about life’s challenges (known as “corumination”) can trigger distancing within a friendship or even lead to the social contagion of depression, self-injury, and suicidality (Developmental Psychology, Vol. 50, No. 9, 2014; Journal of Clinical Child & Adolescent Psychology, Vol. 47, No. 6, 2018).

“Our goal in isolating these different friendship trajectories is to inform interventions for people who are distressed—so that they can keep their relationships and have that crucial social support but not overtax or overstress their relationship partners,” Schwartz-Mette said.

Given the clear benefits of friendship, psychologists say we should promote platonic social connection across society—including in school, at work, in public spaces (such as on public transportation), and through entertainment.

“After having to reduce social contact during the pandemic, we’ve realized how it impacts basically every sector of society,” said Holt-Lunstad. “That suggests that each of these sectors can potentially play a role in solutions.”

Researchers still have a lot to learn about how and why social connection supports health and well-being. The National Institutes of Health and other organizations are distributing funding for studies on “dyadic processes”—or interactions between two people—including exciting new efforts to collect fMRI data on friends while they communicate.

“What we know is that if we don’t interact regularly, things go really bad remarkably fast. But what is the magic in these interactions that’s keeping us healthy and sane?” Wheatley asked. “More and more researchers are saying there’s this huge part of human behavior we know very little about. Let’s change that.”