Studying till late in the night will only fetch poor grades and it is high time to tailor students' class schedules to their natural biological rhythms stress researchers. 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. We found that the majority of students were being jet-lagged by their class times which correlated very strongly with decreased academic performance said study co-lead author Benjamin