College kids who get good shuteye may stand a better chance of making the Dean's list, a new study finds.
"The fact that there was a correlation between sleep and performance wasn't surprising, but the extent of it was," said researcher Jeffrey Grossman. He's a professor in the department of materials science and engineering at Massachusetts Institute of Technology (MIT).
Sleep 'really, really matters'
It's not just how many hours one sleeps that counts, but also the quality of the sleep, including regular sleep times, so getting a good night's sleep before a test won't improve grades. It takes regular, quality sleep to see the benefit, the researchers noted.
For the study, the team gave 100 students Fitbits to keep track of their activities.
The researchers found that students who went to bed around 2 a.m. tended to do poorer on tests, no matter how much sleep they got.
Sleep correlated with how well students did on 11 quizzes, three midterms and final exams, according to the report published in the journal Science of Learning.
The study can't prove a cause-and-effect relationship between sleep and school performance, but the findings provide a strong indication that sleep "really, really matters", Grossman added in an MIT news release.
"Of course, we knew already that more sleep would be beneficial to classroom performance, from a number of previous studies that relied on subjective measures like self-report surveys. But in this study, the benefits of sleep are correlated to performance in the context of a real-life college course, and driven by large amounts of objective data collection," Grossman explained.
Quality of sleep also important
The researchers also found that test scores didn't improve for those who got a good night's sleep right before a test. "The night before doesn't matter," Grossman said. "Instead, it's the sleep you get during the days when learning is happening that matter most."
When you go to bed also matters. "If you get a certain amount of sleep – let's say seven hours – no matter when you get that sleep, as long as it's before certain times, say you go to bed at 10, or at 12, or at one, your performance is the same," Grossman said. "But if you go to bed after two, your performance starts to go down even if you get the same seven hours. So, quantity isn't everything."
Quality of sleep is also important. Those who got consistent amounts of sleep each night did better than those who had more changes from one night to the next, even if they had the same average amount of sleep.
Over the years, Grossman had noticed that, on average, women consistently get better grades than men. The reason may be sleep, he suggested.
"If we correct for sleep, men and women do the same in class. So, sleep could be the explanation for the gender difference in our class," he said.
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