Nap time crucial to preschool memory formation

Any parent knows that a daytime nap helps keep preschoolers from getting cranky. Now a small study suggests that afternoon siestas can not only stave off tantrums but also help them learn, too.

The lesson for grown-ups: Don't cut out the naps if you try to cram more learning activities into a preschooler's day, say researchers from the University of Massachusetts Amherst.

They studied 40 children, ages 3 to 5. In the mornings of test days, the children were shown a grid with pictures of nine or 12 items like a cat or an umbrella. That afternoon and the next morning, the children were tested on how well they remembered the location of each image.

All the children were tested twice. First, half of the children were encouraged to nap before the afternoon test, while the other half of the children were kept awake. The following week, researchers administered the test a second time but reversed the two groups. Without a nap, they were about 65 percent accurate. With a nap, their accuracy reached about 75 percent.

The research shows that "naps are important for preschool children," Rebecca Spencer, senior author of the study, said in a statement.

"If they stayed awake they forgot more of the items they had remembered in the morning, whereas if they took a nap, they remembered all the items they had learned in the morning," said Ms. Spencer at the University of Massachusetts in Amherst.

“This will hopefully be the science to protect naps in the classroom” for preschoolers, Spencer told ABC News.

This news comes as some preschools have been considering reducing or eliminating nap times from their routines. Parents have long pressured teachers to limit or prevent nap time so that children will be able to fall asleep faster at night. While a good night's sleep has long been shown to help reinforce memory and learning, this study suggests that for preschool age children, sleeping at night does not make up for a lack of nap during the day.

However, the effect was most pronounced among habitual nappers, indicating that as children mature and "grow out of" naps, they no longer need that midday time to consolidate their memories. The key appears to be following the child's cues. If a child is given the consistent opportunity to nap but still does not fall asleep, that may be because she no longer needs the nap. That may be of little consolation to parents of children who resist nap even when they are obviously tired.

The study was published yesterday by the Proceedings of the National Academy of Sciences.