My students have sometimes been quick to dismiss some scientific finding as obvious: “Why did someone even need to do a study to show this? It’s just common sense!” Except, common sense isn’t always correct sense. And over the weekend while studying for exams, I think a great many of our students might have gone wrong following “common sense”, and been much better off if they’d heard about some of the tests of the obvious that turned out to be not so obvious. It breaks down this way:
Common sense: Spending more time studying the night before, will mean better performance in school the morning after.
Science: Give up on the studying and get some sleep.
It may seem wrong for a college professor to tell someone to stop studying. And I do wish my students studied more. But even more than studying, I wish they would just sleep more.
Perhaps my students would benefit from keeping a two-week diary, the way some 500 Los Angeles high school students did for today’s study. Each night, students would complete a survey that included questions about how much sleep they had gotten the night before, how much time they spent studying that day, and whether they had encountered problems in school such as getting a bad grade on an assignment, or having trouble understanding something in class. (They were given a nifty electronic stamper to seal each day’s diary with, to show that they had really done it that day).
One would think – and I’m sure most parents and teachers would insist – that the more time students spend studying, the better off they would be the next day. Instead, particularly in the their senior year of high school, the more time students spent studying one day, the more bad grades or difficulty understanding they reported the next day. And it wasn’t that they were putting in the most hours studying when they had a difficult assignment to turn in, or a big test the next day, because that was controlled for. Studying one day seemed to lead to trouble the next.
It flies in the face of common sense, until you consider where some of the extra time spent studying comes from: time that would otherwise have been spent asleep. The studying time didn’t just come from sleeping time, fortunately; only average, high school seniors who did not study at all got about 7 hours of sleep, while those who studied 3 hours got about 6.5 hours of sleep. But that lost half hour of sleep seems to be enough to start showing the cognitive sluggishness that comes from sleep deprivation. A little difficulty paying attention here, or dozing off there, and a little slower to pull something from memory, and suddenly any benefits from those extra hours studying may be wasted.
Now, this isn’t to say that there aren’t times when studying for an exam may be a better idea than sleep. The advice here is that if you’ve been studying for two hours, and you’re still not feeling quite confident, but it’s bedtime, then just go to bed. On the other hand, if you haven’t studied at all, then you might just be better off sleep deprived but slightly knowledgable than awake but without any information for that refreshed brain to retrieve. But on the whole, exam weeks might go much more smoothly if the students translated their determination into getting an A into an insistence in getting a decent night’s sleep. The all-nighters can wait until exams are over, and summer has begun.
Gillen-O’Neel C, Huynh VW, & Fuligni AJ (2013). To study or to sleep? The academic costs of extra studying at the expense of sleep. Child Development, 84 (1), 133-42. PMID: 22906052