When my wife and I moved to New York City in 2001, recently graduated from college and newly wed, we were eager to find friends. We knew nearly no one but were sure we’d soon find a fun-loving group like the 20- and 30-something New Yorkers who spontaneously dropped in on one another on TV shows like Seinfeld and Friends.

We hatched a plan. After moving into our Midtown Manhattan apartment, we invited all the neighbors over for drinks by placing Kinko’s-printed quarter-sheets into everyone’s mailboxes. Then, we waited for our versions of Chandler, Kramer, and Elaine to show up. But they didn’t. In fact, no one did. As the ice in the cooler melted and the guacamole browned, not a single person among 100 apartments stopped by. Not. One. Person.

Recalling that episode now, we sound embarrassingly naïve. We didn’t realize friendships in the real world worked nothing like the ones we had forged in our dormitories, let alone those we saw on television. Yet as it turns out, our desire to belong to a tight community was far from foolish.

Recent studies have shown a dearth of social interaction with people you care about and who care about you not only leads to loneliness, but is also linked to a range of harmful physical effects. In other words: A lack of close friendships may be hazardous to your health.