Study connects college students’ grades to sleep schedules

( CNN) Biding up late to cram for an early exam may not be doing college student any good, according to a new survey focused on college students and their sleep patterns.

The study, published Monday in the publication Scientific Reports, says college students who did not go to bed or wake up at consistent days every day were more likely to have lower grades.

For the study, 61 students from Harvard College maintained online diaries of their sleep schedules for 30 days. Researchers identified two groups: regular sleepers, or those who went to bed and woke up about the same period every day, and irregular sleepers, who had different sleep patterns every day.