This study, led by Laura Kurdziel, a doctoral student in the Neuroscience and Behavior Program at the University of Massachusetts in Amherst, looked for links between preschoolers' regular naps and learning.
The researchers studied 40 preschool children, including 31 girls, who ranged from 3 to 5 years old.
The researchers collected information from the parents in questionnaires about the children's nighttime sleep habits, and the 17 children who regularly napped (at least five days a week) were noted.
The 10 children who were determined not to be regular nappers were those who napped less than two days a week.
One morning at preschool, the children participated in a memory task similar to a memory card game.
The children repeated the task until they got either 7 out of 9 correct items or 9 out of 12 correct items (matching a photo to where the card showing that photo was).
On average, it took the children two to three attempts to reach the minimum correct matches.
The nappers got 75 percent of the tasks correct while those kept awake got 65 percent correct.
However, the bigger benefit in learning and memory among the children who took naps was for those who regularly napped at least five days a week.
The children who did not regularly take naps did not appear to benefit from the nap in terms of learning and memory skills.
"The present results illustrate a benefit of mid-day naps on learning in the preschool classroom," the researchers wrote. "Following a nap, children recalled 10 percent more of the spatial locations than when they had been kept awake during the nap opportunity."
The researchers said the differences in performance when the kids did not nap did not appear related to poor attention or alertness because the learning benefit remained the next day for children who had napped.
"Thus, the negative effects of nap-deprivation on memory consolidation cannot be reversed with overnight sleep," the researchers wrote.
This study was published September 23 in the Proceedings of the National Academy of Sciences. The research was funded by the National Institutes of Health and a Commonwealth College Honors Research Grant. No disclosures were reported.