Even if all goes well for you in high school — you keep your grades up, you engage in extracurricular activities, and you never fall on your face in front of everyone in the cafeteria — that time of life still can be tough.

There's so much to learn academically (physics, chemistry, calculus) and socially (getting along with peers, dealing with teachers or coaches, handling a first romance). But of all those challenges, making good friends might be the most important.

According to a new study published in the journal Child Development, BFFs likely have a significant impact on how you fare in your 20s. Researchers found that those with strong, intimate bonds with their friends at age 15 were more likely to be healthy and happy later. Importantly, popularity — defined as lots of people liking you generally, but not closely — wasn't found to have the same benefit as close friends.

"Close friendship strength in mid-adolescence predicted relative increases in self-worth and decreases in anxiety and depressive symptoms by early adulthood," according to the authors of the study. Popularity actually had the opposite — negative — effect.

The University of Virginia researchers who ran the study followed the 169 subjects every year for a decade (from age 15 to 25), which means that their data is pretty strong. The scientists weren't relying on recollections of the types of relationships people had years later; they got data in real-time from their subjects as they grew and matured.

Importantly, too, the teens were a good representative sample: They were "racially, ethnically and socioeconomically diverse, with 58 percent Caucasian, 29 percent African American, and 8 percent of mixed race/ethnicity, and with median family income $40,000 to $59,999," according to a press release.

Each year, the subjects spoke to the researchers about their friends — who their besties were and what their relationships were like with other friends. Through interviews and assessments, they were asked about "anxiety, social acceptance, self-worth and symptoms of depression; teens' close friends also reported on their friendships and were interviewed," according to the release.

Then the researchers analyzed the 10 years of data to understand how people handle stress over time. Those who were merely popular did worse on several measures of mental health compared to people with strong high school friendships.

"Our study affirms that forming strong close friendships is likely one of the most critical pieces of the teenage social experience," said Joseph Allen, the Hugh P. Kelly Professor of Psychology at the University of Virginia, who coauthored the study.

While some teenagers can manage both close friendships and popularity, usually "different personal attributes" attract high schoolers to one side or the other. Why does this matter?

Because, as Allen wrote, "Being well-liked by a large group of people cannot take the place of forging deep, supportive friendships. And these experiences stay with us, over and above what happens later. As technology makes it increasingly easy to build a social network of superficial friends, focusing time and attention on cultivating close connections with a few individuals should be a priority."

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.