Quit smoking. Turn off the computer. Go to bed. ¶ It could improve your grades. Of course, parents have always known that. Now, in the first study of its kind, researchers at the University of Minnesota have proved it. They matched grade point averages with the typical health problems such as smoking, drinking and stress reported by nearly 10,000 Minnesota college students. They found a clear connection between student health and academic success.

"Health is important," even for young adults who seem to be in the prime of their lives, said Dr. Ed Ehlinger, director of Boynton Health Services at the University of Minnesota and a lead author of the study. Both parents and college administrators "need to make sure that students have access to health care."

What affects grades the most? Stress (lots of it), excessive screen time, binge drinking and gambling.

Students who reported eight or more emotional stresses -- anything from failing a class to credit card debt to a conflict with parents -- had an average GPA of 2.72. Those who said they had no significant stress reported an average GPA of 3.3.

"Stress is one of the biggest factors," said Marcus De La Garza, a senior from Duluth. A year ago, just before finals, he had to go home to take care of family members with serious health problems, and it showed in his grades, he said.

"I was out of the game," he said Friday. "Now I'm bouncing back." His GPA is up to 3.5.

The ability to handle stress was equally important, the survey found. Those who said they could effectively manage it performed much better than those who said they couldn't. That's an important finding, because it can persuade colleges to provide students with the resources they need to learn how to manage stress, Ehlinger said.

Earlier surveys showed that students who spend a lot of time on the computer, watching TV or playing video games were more likely to engage in other unhealthful habits such as eating fast food, Ehlinger said. Now it's clear that these activities cut significantly into their grades as well. Four or more hours of screen time a day resulted in an average GPA of 3.04 or less. Less than an hour a day bumped it up to 3.3 or better.

The same pattern held with binge drinking. Teetotalers reported an average GPA of 3.31, compared with 2.99 for students who drank excessively at least once in the previous two weeks.

Ben Flatum, a university senior from Stillwater, just completed what he called "the year of being healthy." He stopped the regular partying, started eating better and began training for a race in Chicago that he ran last week.

"My time and energy has been exponentially better," he said. His weight is down 25 pounds, and his GPA is up to 3.3 from the 2.5 he had as a partying freshman.

There were some surprises, especially in how resilient young adults can be, Ehlinger said. Students who said they had been sexually or physically abused at some point in their lives had no significant differences in their GPA compared with other students. It shows, he said, that with time, young adults can overcome such trauma, at least as far as their grades are concerned. Those who reported being sexually assaulted or abused in the previous 12 months reported lower grades.

Working to earn money had no effect on grades, another surprise, Ehlinger said. That was true regardless of whether students spent one or 40 hours a week at work.

"There must be something else going on that is protective of folks that are working," Ehlinger said. "It might be a matter of time management."

But Mom and Dad probably knew that, too.

Josephine Marcotty • 612-673-7394