It may be time to tailor students’ class schedules to their natural biological rhythms, according to a new study from UC Berkeley and Northeastern Illinois University, reports Berkeley News.

Researchers tracked the personal daily online activity profiles of nearly 15,000 college students as they logged into campus servers. After sorting the students into “night owls,” “daytime finches” and “morning larks” — based on their activities on days they were not in class — researchers compared their class times to their academic outcomes.

Their findings, published today in the journal Scientific Reports, show that students whose circadian rhythms were out of sync with their class schedules – say, night owls taking early morning courses – received lower grades due to “social jet lag,” a condition in which peak alertness times are at odds with work, school or other demands.