TUESDAY, June 14 (HealthDay News) -- Scheduling classes later in the day provides college students with more time to sleep in the morning, but it may also encourage them to stay up later drinking, new research suggests.

Researchers found that undergrads whose classes started later were more likely to binge drink and get lower grades.

"Later class start times predicted more drinking, more sleep time and modestly lower grades, overall," said the study's co-lead author Pamela Thacher, associate professor of psychology at St. Lawrence University in Canton, N.Y. in a news release from the American Academy of Sleep Medicine. "Later class start times seemed to change the choices students make: They sleep longer, and they drink more."

The study is slated for presentation on Tuesday at SLEEP 2011, the Associated Professional Sleep Societies meeting in Minneapolis.

Thacher and her colleagues asked 253 college students to perform cognitive tasks and keep a sleep diary for one week. They were also given questionnaires regarding their sleep, class schedules, substance use and mood.

The study found that students who had later class start times tended to stay up later, were not as well rested, had more daytime sleepiness and earned slightly lower grade point averages.

Students with this schedule also reported more alcohol use and more binge drinking. Self-described "night owls" were more likely than students who consider themselves "morning people" to drink more, the study noted.

Thacher concluded that drinking more at night negated the benefits of being able to sleep in -- especially because alcohol tends to disrupt sleep. "The effects of later class start times might include more sleep," she said. "But this might be offset by lower quality sleep, which in turn might affect their ability to engage intellectually with their coursework."

The same may not be true however, for younger students. The study's authors pointed out previous studies of elementary and high school students found later school start times may improve attendance and mood among students.

Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

The National Sleep Foundation offers tips on healthy sleeping habits.