Category Archives: Sleep

Up With Science! Down With School in the Morning!

New York magazine has an article about sleep deprivation in children, claiming that they enjoy an hour less sleep per night compared to 30 years ago. It goes on to suggest that sleep loss lowers intelligence and causes obesity and mental illness. The article references a bunch of recent research in the field, including a study by Prof. Avi Sadeh of Tel Aviv University.

A couple of years ago, Sadeh sent 77 fourth-graders and sixth-graders home with randomly drawn instructions to either go to bed earlier or stay up later for three nights. Each child was given an actigraph (a wristwatchlike device that’s equivalent to a seismograph for sleep activity), which enabled Sadeh’s team to learn that the first group managed to get 30 minutes more sleep per night. The latter got 31 minutes less sleep.After the third night’s sleep, a researcher went to the school in the morning to test the children’s neurobiological functioning. The test they used is highly predictive of both achievement-test scores and how teachers will rate a child’s ability to maintain attention in class.

Sadeh knew that his experiment was a big risk. “The last situation I wanted to be in was reporting to my grantors, ‘Well, I deprived the subjects of only an hour, and there was no measurable effect at all, sorry—but can I have some more money for my other experiments?’” he says.

Sadeh needn’t have worried. The effect was indeed measurable—and sizable. The performance gap caused by an hour’s difference in sleep was bigger than the normal gap between a fourth-grader and a sixth-grader. Which is another way of saying that a slightly sleepy sixth-grader will perform in class like a mere fourth-grader. “A loss of one hour of sleep is equivalent to [the loss of] two years of cognitive maturation and development,” Sadeh explains.

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