A new study shows that college students with poor sleep are much more likely to earn worse grades and withdraw from a course than healthy sleeping peers. The study also found that sleep problems have about the same impact on grade point average (GPA) as binge drinking and marijuana use.

Results show that sleep timing and maintenance problems in college students are a strong predictor of academic problems even after controlling for other factors that contribute to academic success, such as clinical depression, feeling isolated, and diagnosis with a learning disability or chronic health issue.

Its negative impact on academic success is more pronounced for freshmen. Among first-year students, poor sleep— but not binge drinking, marijuana use or learning disabilities diagnosis—independently predicted dropping or withdrawing from a course. Results were adjusted for potentially confounding factors such as race, gender, work hours, chronic illness, and psychiatric problems such as anxiety.

“Well-rested students perform better academically and are healthier physically and psychologically,” said investigators Roxanne Prichard, PhD, associate professor of psychology and Monica Hartmann, professor of economics at the University of St. Thomas in St. Paul, Minnesota.

According to Prichard, student health information about the importance of sleep is lacking on most university campuses.