Photo: Reisig & Taylor/NBCU Photo Bank

Social networks tend to follow predictable cycles throughout a person’s life, expanding in the 20s and shrinking in the 30s and beyond, a notion borne out by social-science research and popular trend pieces alike. Now, a new study takes this idea and fast-forwards several decades into the future, giving a hint about the long-term impact of this friendly ebb and flow.

According to the study, led by Cheryl L. Carmichael of Brooklyn College and the Graduate Center at CUNY, and published recently in the journal Psychology and Aging, your middle-age happiness can be predicted by two things: the quantity of friends in your 20s, and the quality of friendships in your 30s. In a way, your 50-year-old self stands to benefit both from the endless rounds of flip cup with college pals and the long talks with close friends a decade later.

The researchers used a data set involving more than 200 University of Rochester students, who in the 1970s and 1980s had been asked to keep daily diaries tracking their social interactions for two weeks, once when they were about 20 years old and again when they were about 30. Each time, they were to note both how many people they interacted with each day and to rate the intimacy and pleasantness of the interaction. Then in 2007 and 2008, when they were about 50, a little more than 100 of those former students took a series of tests to measure their psychological health, including their levels of loneliness, depression, and overall well-being. As it turned out, having a higher number of interactions in the 20s predicted greater well-being in the 50s; in the 30s, however, the quality of the social connections mattered more.

The study isn’t a perfect one. For one, Carmichael acknowledges that this is a limited slice — mostly white, relatively well-educated, and well-off — from which to draw these conclusions. And there’s also the fact that adulthood is pretty different in 2015 than it was in the 1980s, when these study participants were in their early 30s; it’s more common now for young adults to delay marriage and family, for instance. “Our reference to age 20 as early adulthood may, nowadays, be more aptly described as very early adulthood, whereas by age 30, people often feel they have fully entered adulthood,” Carmichael writes. “The developmental changes that we ascribe to 30-year-olds may have taken place by age 30 for many in this late baby-boom cohort, but may unfold at a later age (e.g. closer to age 40) for other generations.” Also, imagine if this study were to be replicated today, with the inclusion of social media. How many “social interactions” have you had in the last two hours, let alone the last two weeks?

Still, if this is the pattern your social life has taken, the researchers do explore some interesting potential reasons why. There’s the obvious, for one — the fact that for many people, the 30s are the years of marriage, kids or career (or all three at once!), leaving less time for keeping up with tons of friends.

But there’s also this: In early adulthood, you’re still figuring yourself out, trying on different selves and ways of being; it makes sense that you’d want a larger circle of friends, with personalities you can borrow from time to time. “However, as individuals approach their 30s, social information-seeking motives wane,” Carmichael and her co-authors write. “Identity exploration goals diminish with the transition into better-defined and more enduring social roles.” You start to have a better idea of who you are in your 30s, meaning that you aren’t so reliant on people in your social circle to give you ideas of who you could be. In other words: If you’re concerned because you have fewer friends than you did in college or in the years shortly after, relax. You’ll be fine.