Naps don't just provide children with much-needed rest: They may aid in learning too.
New research shows that children who had a midday nap performed better on memory recall tests than those who weren't able to get any extra snooze time.
The study authors hope they can convince more schools to require nap time.
"Until now, there was nothing to support teachers who feel that naps can really help young children. There had been no concrete science behind that," Dr. Rebecca Spencer, an assistant professor in the department of psychology at the University of Massachusetts Amherst, said in a press release. "We hope these results will be by policy makers and center directors to make educated decisions regarding the nap opportunities in the classrooms. Children should not only be given the opportunity, they should be encouraged to sleep by creating an environment which supports sleep."
The research team looked at 40 children from six preschools across western Massachusetts. The kids were instructed to play a game which tested their so-called "visual-spatial" recall. They were shown a grid of pictures and had to remember where different images were located, similar to the game Memory.
The preschoolers started playing the game at 10 a.m. and stopped when they were able to accurately remember where 75 percent of the images were located. After the game, the kids were divided into the groups. Kids in the first group were encouraged to nap and slept about 77 minutes on average. The second group did not nap at all.
Kids who took a nap were able to remember about 75 percent of the items once they woke up and got tested again. However, those who did not nap only remembered about 65 percent of them, a 10 percent difference.
Memory was tested again one day later to make sure test performance had nothing to do with how alert the kids were. The scores did not change.
The researchers also asked 14 additional children to come to a sleep lab and had them undergo a polysomnography, or a sleep study, which records brain waves, oxygen levels and other bodily processes that occur during shut-eye. The researchers wanted to say whether memories were actively processed during naps.
The kids napped for an average of 73 minutes during the test.
The researchers linked the nap-induced memory boosts with an increase in the amount of sleep spindles seen on the tests. Sleep spindles are bursts of activity that occur when the brain keeps new information it learns.
The study authors called for preschools to create napping guidelines and encouraged more research on how to keep and promote naptime for kids to help with their learning abilities. Spencer said to the Guardian parents and preschools often skip naptime, and this study shows just how important it is to make sure kids get their rest.
"This is the science that's needed to preserve nap time," she said. "If our goals are to prepare children for early education, the naps are consistent with that goal because it's really helping them to learn."
The study was published in the Proceedings of the National Academy of Sciences on Sept. 23.