These rates are self-reported, so it’s important to take them with a grain of salt: Students may just be saying they’re socializing less, when in reality they’re avoiding the library like prison. But it can cut the other way too; maybe students are indeed partying less often and are afraid to admit that they’re spending more time hitting the stacks. Tracking such norms, the Cooperative Institutional Research Program at UCLA has conducted the survey annually since 1966.

"When we look at the data, it seems that the reasons students are attending college have changed," said Kevin Eagan, lead author of the study. "Years ago, it may have been wanting to become a cultured person and having a fulfilling social life that motivated students. Now we’re seeing more concerns from them about finance while enrolled in college and getting a high-paying job after graduating." (Eagan said "socializing" referred to in-person interactions between individuals.)

Although the study did not address the precise causes of these trends—are students partying less because they’re more stressed?—it confirmed that social-media use among incoming freshmen has risen steadily over the past several years. In 2014, 27.2 percent of students entering college said they spent six hours or more per week on online social networks, up 8.3 percent from 2007 (one year after Twitter was founded). To put that in perspective, research compiled by the Pew Research Center last year showed that 89 percent of Americans between the ages of 18 and 29 used social-networking sites; this was an 80 percent jump from 2005, and 10 percentage points above the average rate for all American Internet users in 2014.

But just because more students are on Facebook doesn’t mean they’re staying in more, right? That’s very well possible, especially considering that a growing number of people access social-networking sites from their mobile phones while on the go. Still, social-media use has been correlated with feelings of loneliness and depression, so more people could be using it as a substitute for in-person interactions. Four years ago, a study involving more than 1,000 Australian Internet users found that "neurotic and lonely individuals [tend to] spend a greater amount of time on Facebook per day than non-lonely individuals." Furthermore, while Facebook may not be creating loneliness (‘correlation does not imply causation,’ the saying goes), it could be linked to marginal increases in sadness. In 2010, Moira Burke—then a graduate student studying human-computer interaction at Pittsburg's Carnegie Mellon University—reported that Facebook users who consumed more content on the site experienced elevated loneliness and felt they had less social capital. Last year, however, she published a paper called "Growing Closer on Facebook," which argued that social ties strengthened "with both one-on-one communication, such as posts, comments, and messages, and through reading friends’ broadcasted content, such as status updates and photos." Facebook also had a greater effect on non-family relationships that didn’t involve other forms of communication, like texting.