Most people view emotions as existing primarily or even exclusively in their heads. Happiness is considered a state of mind; melancholy is a potential warning sign of mental illness. But the reality is that emotions are inherently social: They’re woven through our interactions.

Research has found that people laugh five times as often when they’re with others as when they’re alone. Even exchanging pleasantries with a stranger on a train is enough to spark joy. That’s not to say you can’t find delight in watching a show on Netflix. The problem is that bingeing is an individual pastime. Peak happiness lies mostly in collective activity.

We find our greatest bliss in moments of collective effervescence. It’s a concept coined in the early 20th century by the pioneering sociologist Émile Durkheim to describe the sense of energy and harmony people feel when they come together in a group around a shared purpose. Collective effervescence is the synchrony you feel when you slide into rhythm with friends on a dance floor, join teammates for a kick about,  do downward dogs with likeminded souls on your yoga mat!!

Collective effervescence happens when joie de vivre spreads through a group. Before Covid, research showed that more than three-quarters of people found collective effervescence at least once a week and almost a third experienced it at least once a day. They felt it when they sang in choruses and ran in races, and in quieter moments of connection at coffee shops and in yoga classes.

Emotions are like contagious diseases: They can spread from person to person. “Emotional contagion is when we are literally infected with other people’s emotions,” Sigal Barsade, a management professor and a leading researcher on the topic, has explained. “In almost all of our studies, what we have found is that people don’t realize it’s happening.”

When the pandemic began in 2020, the first negative emotion to spread was fear. Waves of panic crashed through communities, compelling people to purify packages and hoard hand sanitizer. As too many people lost loved ones, too many others lost jobs and everyone lost some semblance of normal life. The number of adults with symptoms of depression or anxiety spiked from one in 10 to about four in 10.

And there’s reason to believe these symptoms haven’t been caused only by the crisis itself — they’ve actually been transferred from person to person. Studies show that if your spouse, your family member or your roommate develops depression, you’re at heightened risk for it. And contagion isn’t limited to face-to-face interaction: Emotions can spread through social media posts and text messages, too.

Psychologists find that in cultures where people pursue happiness individually, they may actually become lonelier. But in cultures where they pursue happiness socially — through connecting, caring and contributing — people appear to be more likely to gain well-being.

The American Declaration of Independence promised unalienable rights to life, liberty and the pursuit of happiness. If we want that pursuit to bring us bliss, it may be time to create a Declaration of Interdependence. You can feel depressed and anxious alone, but it’s rare to laugh alone or love alone. Joy shared is joy sustained.