The Power of Close Relationships

The Lifelong Power of Close Relationships

In its 85 years and counting, the Harvard Study of Adult Development has found that personal connections are the most important factor in long-term health and happiness.

By Robert Waldinger and Marc Schulz

Jan. 13, 2023

This couple in their 80s have been married for 62 years. The more time older couples spend with one another, the happier they report being. Tonje Thilesen For The Wall Street Journal

When it comes to understanding what happens to people as they go through life, pictures of entire lives—of the choices people make and the paths they follow, and how it all works out for them—are almost impossible to get. Most of what we know about human life we know from asking people to remember the past, and memories are full of holes. The more time that passes, the more details we forget, and research shows that the act of recalling an event can actually change our memory of it.

What if we could watch entire lives as they unfold through time?

But what if we could watch entire lives as they unfold through time? What if we could study people from the time that they were teenagers all the way into old age to see what really matters to a person’s health and happiness, and which investments really paid off? For 85 years (and counting), the Harvard Study of Adult Development, which we now direct, has tracked an original group of 724 men and more than 1,300 of their male and female descendants over three generations, asking thousands of questions and taking hundreds of measurements to find out what really keeps people healthy and happy.

Through all the years of studying these lives, one crucial factor stands out for the consistency and power of its ties to physical health, mental health and longevity. Contrary to what many people might think, it’s not career achievement, or exercise, or a healthy diet. Don’t get us wrong; these things matter. But one thing continuously demonstrates its broad and enduring importance: good relationships.

In fact, close personal connections are significant enough that if we had to take all 85 years of the Harvard Study and boil it down to a single principle for living, one life investment that is supported by similar findings across a variety of other studies, it would be this: Good relationships keep us healthier and happier. Period. If you want to make one decision to ensure your own health and happiness, it should be to cultivate warm relationships of all kinds.

Friends photographed in Brooklyn. Most of us have friends and relatives who energize us and who we don’t see enough. Photo: Tonje Thilesen For The Wall Street Journal

The Harvard Study of Adult Development began in Boston in 1938, when two unrelated groups of researchers began closely following very different groups of boys. The first was a group of 268 sophomores at Harvard College, selected by Harvard professor of hygiene Arlie Bock because they were deemed likely to grow into healthy and well-adjusted adults. At least half of the young men chosen for the study attended Harvard with the aid of scholarships and by holding down jobs to help pay tuition, while others came from well-to-do families. Some could trace their roots in America to the founding of the country, and 13% of them had parents who had immigrated to the U.S.

The second project looked at 456 14-year-old boys who were growing up in some of Boston’s most troubled families and most disadvantaged neighborhoods, but who had mostly succeeded in avoiding the paths to juvenile delinquency. More than 60% of these adolescents had at least one parent who had immigrated to the U.S. Their modest roots and immigrant status made them doubly marginalized.

When the researchers decided to combine the two studies, all of the inner-city and Harvard participants were interviewed. They were given medical exams. Researchers went to their homes and interviewed their parents.

Over the following decades, these teenagers grew up into adults who entered all walks of life. They became factory workers and lawyers and bricklayers and doctors. Some developed alcoholism. A few developed schizophrenia. Some climbed the social ladder from the bottom all the way to the very top, and some made that journey in the opposite direction.

The founders of the Harvard Study would be shocked and delighted to see that it still continues today, generating unique and important findings they couldn’t have imagined in 1938. By hook and by crook, the Harvard Study has maintained an 84% participation rate for 85 years.

Once we had followed the people in the Harvard Study all the way into their 80s, we wanted to look back at them in midlife to see if we could predict who was going to grow into a happy, healthy octogenarian and who wasn’t. So we gathered together everything we knew about them at age 50 and found that it wasn’t their middle-aged cholesterol levels that predicted how they were going to grow old; it was how satisfied they were in their relationships. The people who were the most satisfied in their relationships at age 50 were the healthiest, mentally and physically, at age 80.

This couple has been married for 42 years. In the study, the more time participants spent with their partners, the more happiness they reported. Photo: Tonje Thilesen For The Wall Street Journal

Other long-term studies have come to similar conclusions about the powerful role of relationships. A study tracking 3,720 adults in Baltimore since 2004 found that participants who reported receiving more social support also reported less depression. A study following a representative sample of 229 older adults in Chicago since 2002 found that people in satisfying relationships reported higher levels of happiness. And a study based in Dunedin, New Zealand, found that social connections in adolescence were better than academic achievement at predicting well-being in adulthood.

In 2008, we telephoned the wives and husbands of Harvard Study couples in their 80s every night for eight nights. We spoke to each partner separately and asked them a series of questions about their days. We wanted to know how they had felt physically that day, what kinds of activities they had been involved in, if they had needed or received emotional support, and how much time they had spent with their spouse and with other people.

On days when these men and women spent more time in the company of others, they were happier.

The simple measure of time spent with others proved quite important, because on a day-to-day basis this measurement was clearly linked with happiness. On days when these men and women spent more time in the company of others, they were happier. In particular, the more time they spent with their partners, the more happiness they reported. This was true across all couples but especially true for those in satisfying relationships.

Like most older people, those in the Harvard Study experienced day-to-day fluctuations in their levels of physical pain and health difficulties. Not surprisingly, their moods were lower on the days when they had more pain. But we found that the people who were in more satisfying relationships were buffered somewhat from these ups and downs of mood—their happiness did not decline as much on the days when they had more pain. Their happy marriages seemed to have a protective effect.

This finding makes sense in light of the growing evidence that loneliness is associated with greater sensitivity to pain, suppression of the immune system, diminished brain function and less effective sleep. Recent research has shown that for older people, loneliness is twice as unhealthy as obesity, and chronic loneliness increases a person’s odds of death in any given year by 26%.

How can loneliness be so physically harmful when it’s a subjective experience? Answering that question is easier if we understand the biological roots of the problem. Human beings have evolved to be social, and the biological processes that encourage social behavior are there to protect us. When we feel isolated, our bodies and brains react in ways that are designed to help us survive that isolation.

Fifty thousand years ago, being alone was dangerous, and an isolated person’s body and brain would have gone into temporary survival mode. The need to recognize threats would have fallen on her alone, so her stress hormones would have increased and made her more alert. If her family or tribe were away overnight and she had to sleep by herself, her sleep would be shallower. If a predator was approaching, she would want to know, so she would be more easily aroused and experience more awakenings during the night.

When we feel isolated, our bodies and brains react in ways that are designed to help us survive that isolation. Photo: Tonje Thilesen

If for some reason she found herself alone for say, a month, rather than a night, these physical processes would continue, morphing into a droning, constant sense of unease, and they would begin to take a toll on her mental and physical health. She would be, as we say today, stressed out. She would be lonely.

The same effects of loneliness continue today. The feeling of loneliness is a kind of alarm ringing inside the body. At first, its signals may help us; we need them to alert us to a problem. But imagine living in your house with a fire alarm going off all day, every day, and you start to get a sense of what chronic loneliness is doing behind the scenes to our minds and bodies.

Today we live in much more complicated environments, so meeting our social needs presents different challenges. Think for a moment about a relationship you have with a person you cherish but feel like you don’t see nearly enough. How many hours do you think you spend with this person in a single year? If you’re 40, and you see them once a week for a coffee hour, that adds up to the equivalent of 87 days together before you turn 80. If you see them once a month, it’s about 20 days. Once a year, about two days.

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Appeared in the January 14, 2023, print edition as ‘The Real Secret of LIFELONG FULFILLMENT For a Longer, Happier Life, Invest in Relationships’.