Read: What makes us happy?

So we investigated four indicators of sociability among today’s young adults—marriage, friendship, religious attendance, and sex—in an effort to explain the “happiness recession” among today’s young adults.

First, we looked at marriage. Controlling for basic demographics and other social characteristics, married young adults are about 75 percent more likely to report that they are very happy, compared with their peers who are not married, according to our analysis of the GSS, a nationally representative survey conducted by NORC at the University of Chicago. As it turns out, the share of young adults who are married has fallen from 59 percent in 1972 to 28 percent in 2018. The decline has been similar for men and women, although from 2016 to 2018 the share of married men fell, while the share of married women rose.

Read: The decline of marriage and the rise of unwed mothers

Data on cohabitation are not available for as long a period, but suggest that the trend in all coupling is probably less steeply negative, though still drifting downward over time. Less coupling, then, probably explains some of the decline in happiness among young adults.

Faith was the second factor. Young adults who attend religious services more than once a month are about 40 percent more likely to report that they are very happy, compared with their peers who are not religious at all, according to our analysis of the GSS. (People with very infrequent religious attendance are even less happy than never-attenders; in terms of happiness, a little religion is worse than none.) What’s happening to religious attendance among young adults today? The share of young adults who attend religious services more than monthly has fallen from 38 percent in 1972 to 27 percent in 2018, even as the share who never attend has risen rapidly. Among young men, nonattendance is much more common than regular attendance, and the gap is steadily growing. Less involvement in the life of a local church, mosque, temple, or synagogue, we speculate, might translate into less happiness for young adults.

The third factor was friendship. The effect of seeing friends frequently is less clear than that of marriage or religion, but young adults who see their friends regularly do seem to be about 10 percent more likely to report being very happy than their less-sociable peers. Friendship among young adults, though, is not on the decline; in fact, since 2006, contact with friends is up. Lack of friendship, then, is not likely to play a role in declining levels of happiness. Indeed, it may be that rising social time spent with friends in recent years could be buffering young adults from the declines in institutions such as marriage or religion, as friends stand in place of other relationships or forms of community.*