For most college students, paying attention during an 8 a.m. class is a Herculean effort — and for good reason. A new study suggests that college-aged brains simply aren’t ready to learn so early in the morning, NPR reports.

The study, published in the journal Frontiers in Human Neuroscience, came about after Mariah Evans, a sociology professor at the University of Nevada, Reno, noticed students falling asleep in her morning classes. Evans suspected there was something going on besides laziness, so she teamed up with a colleague and researchers at The Open University in the U.K. to look at the science behind her students’ exhaustion.

They surveyed 190 first-and-second-year college students on their preferred sleep time, their self-reported chronotype (whether they were early birds, night owls or something in between) and more, and looked at the relationship between sleep and brain function. Their conclusion? College classes — which begin around 8 a.m., on average — start “too early in the morning for students’ brains,” NPR reports.

“It has nothing to do with laziness. It’s not in their control. It’s to do with their bodies,” Jonathan Kelley, one of the researchers from The Open University, told NPR. He adds that forcing students to go to early classes is “like making an adult wake up at 5 a.m. every single day. It is just not a good idea.”

The findings support research on how sleep needs change throughout our lives, suggesting that “teenagers’ body clocks are set at a different time than older folks,” according to Evans. The study also adds to existing research showing how delaying school start times can make a huge difference in students’ academic performance, attendance, motivation and overall health.

Of course, most professors won’t accept “my body clock is different than yours” as a viable excuse for sleeping through class, so until colleges change class start times (Kelley suggests 10 or 11 a.m. instead) students are better off picking later classes in order to be at their best and brightest.

Read more on NPR.

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