Study links college students' grades to sleep schedules

Story highlights

  • Students who did not go to bed or wake up at consistent times were more likely to have lower grades, it says
  • Inconsistent sleep can make your body feel like it's in another time zone, expert says

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

The study, published Monday in the journal Scientific Reports, says college students who did not go to bed or wake up at consistent times every day were more likely to have lower grades.
For the study, 61 students from Harvard College kept 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 time every day, and irregular sleepers, who had different sleep patterns every day.
    There were several differences between regular and irregular sleepers, including significant differences in grade point averages. Using a unique scoring index from zero to 100 to calculate a student's sleep regularity, students with very irregular sleep patterns were given lower scores close to zero, while more regular sleepers were given higher scores close to 100. The researchers found that for every score increase of 10 on the regularity index, the student had an average increase of 0.10 in their GPA.
    Andrew Phillips, lead author of the study and associate professor of medicine at Harvard Medical School, said the findings show that irregular sleepers have a delayed release of the sleep hormone melatonin.
    "Our body contains a circadian clock, which helps to keep time for many biological functions," he said.