School & District Management

Grades Suffer When Class Time Doesn’t Match Students’ Biological Clocks

By Sarah D. Sparks — March 30, 2018 4 min read
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Regardless of whether students like to rise with the dawn or stay up after midnight, new research suggests that when their class schedules fall out of sync with their biological clocks, their grades can suffer.

A study in the journal Scientific Reports suggests students who develop consistent daily class schedules that match their natural body rhythms have better grades—and students whose circadian rhythms don’t match “normal” class days pay the price.

The study comes as more high schools nationwide experiment with an array of school schedules, from late starts to four-day weeks and alternating block classes.

“An important piece of the story is that it’s not just about making the life of a teenager easier by saying maybe we can make classes later,” said Benjamin Smarr, a postdoctoral psychologist at the University of California at Berkeley who studies circadian rhythm disruptions and learning. “It’s about recognizing that these chronotypes [or sleep profiles] are genetic. So these are types of people we are talking about, a genetic predisposition that makes you who you are.”

Owls and Larks

Smarr and biologist Aaron Schirmer of Northeastern Illinois University used the latter university’s online learning management software to track nearly 15,000 college students’ administrative data and logins to the online system over two years. The researchers mapped the average times of day each student was active on the school’s online system to the students’ class schedules, both on class days and free days.

“People are often not really aware of their own habits,” Smarr said. “So they’ll say, ‘Sure, of course I go to bed at 10 every night,’ without realizing that really they start getting ready to go to bed at 10 p.m., but they aren’t falling asleep until midnight or 1 a.m.”

On average, the data backed up what is already known about average sleep cycles. For example, middle-age students tended to get up earlier and go to sleep earlier than younger students, and men were more likely to stay awake into the wee hours than women.

But from those data, Smarr and Schirmer also developed three profiles of students’ sleep cycles. Some students, dubbed “finches,” had circadian cycles that basically tracked the “normal” school day, being most alert and active from 8 a.m. to 4 p.m. Early risers, whose sleep schedule was at least one standard deviation earlier than the average, were called “larks,” while those whose sleep schedules were at least a standard deviation later than average were the “owls.”

“It’s very normal that you would expect to see larks and owls in the population,” Smarr said. “You have circadian genes and they have a feedback loop ... and that cycle takes about 24 hours, but some people have ones that are a little faster; some people have ones that are a little slower.”

Class Mismatch

A little more than 40 percent of students had classes that were within 30 minutes of their most active time of day, the researchers found. By contrast, 49 percent of students took classes before they had fully awakened, while about 10 percent had classes when they had already started to droop in the afternoon.

As it turned out, taking a class schedule mismatched to your biological clock took a toll on students’ grades, as the chart below shows.

Early-rising “larks” had a grade advantage in morning classes, they found. Night owls performed better in afternoon and early evening classes, but the researchers also found these students tended to struggle more than those with earlier circadian rhythms in general. The researchers believe this was because their schedules were the farthest off “normal” class schedules, and the actual class times often varied significantly from day to day, making it difficult for these students to develop any consistency.

“It’s instability more than the lateness getting in the way of students’ ability to achieve,” Smarr said. “It’s not necessary that everybody needs exactly eight hours of sleep—different people have different sleep needs—but you really want to go to sleep at the same time every day. If you don’t, you make it really hard for all your different internal clocks to line up, and that really hurts you.”

Most high schools don’t really have the option to make multiple sessions of the same class at different times, but Smarr said for those who use software that can track the timing of students’ activity, it may be worth getting a sense of when different groups of students are likely to be most alert when scheduling core classes. Other forms of technology may also help, he said, allowing students to access classes or rewatch lectures at different times of the day.

But to some extent, the results also provide a window into adolescents’ behavior in class. “Rather than saying this student is sleeping, or this student is having an emotional reaction and I’m tired of that; that’s a bad student—try framing that conversation as ‘I’m sorry you are having this problem. It’s a real problem, but we need to help you get through your education anyway,’” Smarr said.

Photo Source: Getty

Chart Source: Benjamin Smarr, U.C. Berkeley


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A version of this news article first appeared in the Inside School Research blog.