By guest blogger Helge Hasselmann

Cognitive performance fluctuates throughout the day. Depending on their “chronotype” some people are sharpest in the morning (“larks”), while others generally prefer the later hours of the day (“owls”). For obvious reasons, this is mirrored in our preferred sleep routines: larks get tired in the evenings earlier and, as a consequence, also wake up earlier, while owls show the opposite pattern. Your chronotype is not something that you’re stuck with for the rest of your life, but it changes with age. In fact we’re most likely to show an owl-like chronotype during adolescence, which might at least partly explain why teenagers often stay up late and arrive at school with eyes bloodshot thanks to a hefty sleep debt.

But if late chronotypes are so common in adolescents, why does school start so early (usually well before 9am in the UK, Netherlands and Germany)? Doesn’t that mean that many students are likely to be constantly sleep-deprived and not assessed during their biological peaks? Yes, it does! In fact, there is a lot of evidence to suggest that school kids who have a late chronotype score lower grades. But besides reduced sleep time, there are several alternative explanations for why a late chronotype could be associated with lower academic performance (such as absenteeism, for instance) as explored in a new paper in Scientific Reports. The researchers, led by Giulia Zerbini at University of Groningen, say their findings might help us understand the chronotype/school grade link and how we can fix it.

Continue reading “It’s not just lack of sleep: why pupils with an “owl” chronotype get lower grades” →