As part of the never-ending quest to get more bang for the education dollar, administrators and parents have been questioning the need for preschoolers to nap in school. And as more and more preschools become funded with public money, the calls for naptime to be replaced with more schooling have only grown louder.

Doing away with daily naps could very well be counterproductive. A new study that finds that giving preschoolers a chance to nap during the school day actually helps kids learn.

The study used a variation of the game, “Memory,” in which children are shown cards arranged in a 3 X 3 or 3 X 4 grid, each with an image on them. The children are supposed to remember which card has the lion on it, which card the umbrella, and so on.

The effects of nap deprivation cannot be reversed by overnight sleep.

Forty children from six preschools in Western Massachusetts were taught the game in the morning and came back to it in the afternoon to see how well they remembered which card contained which image. They did this on two different days, one day after their usual early afternoon nap and then again on another day without taking their nap.

Children remembered more of the images correctly when coming back to the game later in the day when they had napped. They made about 10% fewer mistakes than on the day when they had not napped.

The same results were seen on the next day, 24 hours after being taught the game, indicating that the effects of nap deprivation cannot be reversed by overnight sleep.

To further examine what was occurring during the nap, an additional 14 children went through the process in a sleep lab, where their naps were monitored by polysomnography, which records electrical and other physiological activity during sleep.

How much a child's memory benefited from the nap was directly related to the number of sleep spindles on his or her EEG during the nap. Sleep spindles, sometimes called sigma waves, are brief bursts of brain activity during sleep that last only for a second or less but have been associated with memory consolidation in adults.

Naps averaged 77 minutes. The memory biggest benefit was seen in children who also napped regularly outside of school.

These results suggest that it's wrong to begrudge the time children spend napping in class and try to fill it with added instruction. It also suggests that naps could play a part in aiding young children who are having difficulty learning.

The study appears in PNAS, Proccedings of the National Academy of Science and is freely available.