When schools start before 9 am, “owls” get lower grades than “larks,” concludes a new paper in Scientific Reports, writes Helge Hasselmann for Research Digests.

Researchers, led by Giulia Zerbini at University of Groningen, assessed the sleep habits of students at Dutch secondary schools to determine their “chronotypes.”

Those with late chronotypes — owls — earned significantly lower grades in science (except for physics) and math, even if they got a full night’s sleep. However, they did as well as their lark classmates when they took exams in the afternoon. Chronotype did not affect performance in humanities/linguistic subjects.

Teens often are owls. Some British schools have experimented with later start times — as late as 10 am — to help students do their best, writes Hasselmann. He also suggests scheduling science classes for the afternoon.