Small children give up naps at different ages. A new theory links this transition to brain development.

She and her colleagues sought to understand why. In an article published on Monday that links his previous research to that of other scientists, they posit that brain development, not age, as many parents might expect, is the reason for this variation.

Spencer’s research underscores the importance of giving all young children the opportunity to sleep during the day, she said.

Children’s brains can only hold a limited amount of information. they need naps to organize and retain all the stimuli and sensations bombarding them, she explained.

“When they don’t nap, they actually show memory loss,” said Spencer, who co-authored the paper in the Proceedings of the National Academy of Sciences, with Tracy Riggins, a child psychologist from the University. ‘University of Maryland. “It is detrimental for them to stay awake during naps.”

But children whose brains have matured to the point where they no longer need to nap “can stay awake without this catastrophic effect on memory,” Spencer said.

Spencer and Riggins have spent years studying the relationship between children’s sleep patterns, their performance on memory tests, and the rate at which different areas of their brains mature. A study they published in the journal Nature in 2020 found that children who gave up naps had a more developed hippocampus, the area of ​​the brain involved in memory and learning, than children who still slept during the day.

The hippocampus undergoes tremendous growth during infancy, and this growth occurs at a different rate in each child. It also occurs during the same period as the transition away from the daily nap.

“We know there are key developmental patterns at this age . . . in a way that we think is relevant to how children sleep,” Spencer said.

School leaders don’t always recognize the importance of naps, Spencer said. California’s new universal pre-K program does not require a nap. In New York, naps are suggested, but not required.

In Massachusetts, preschool programs must give children a 45-minute “opportunity to rest.” Spencer finds this both vague – what is a rest opportunity? will the lights be on? – and insufficient. Most preschoolers need 70 to 90 minutes of sleep during the day, she said.

When children are deprived of necessary naps, “you slow down cognitive development. Day to day, they don’t remember enough,” she said.

Sleeping more at night will not compensate for this. “Sleep has to happen close to learning,” Spencer said.

Transitioning out of naps isn’t like flipping a switch, she warns. Children may skip naps for a while and then resume them.

Spencer hopes her theory, drawn from her previous research and others, will spur more studies of children’s sleep. If a way to assess the functioning of the hippocampus could be developed, parents and teachers might be able to identify which children still need naps and which do not. Meanwhile, she said: “It’s best to encourage all children to have some quiet time and settle down to see if they can nap.”

How can a parent today know if their child no longer needs to take a nap? Currently, parents say by observing that naps are becoming less frequent, shorter, and a child’s behavior becomes less challenging when they miss a nap, she said. “But differentiating these cues from a child who is hesitant to nap . . . can be difficult,” she added.

Rebecca Gómez, professor of cognition and neural systems and director of the Child Cognition Lab at the University of Arizona, notes that even children who have stopped napping sometimes need to doze off when they’re confronted with difficult concepts. “When the information is more complex, children cannot form a strong memory during the learning experience. These kids might still need a nap,” she said.

Spencer’s essay raises “all sorts of intriguing and important questions, and really puts this nap issue on the map for parents,” Gómez said. “This theory will be very important in the conduct of research.”

But she suspects that more than the hippocampus is involved.

“It really needs to be expanded with all the developmental changes that are happening,” Gómez said. “I don’t think it’s just the changes in the hippocampus that are causing this.”

“Sleep affects every system in the body and brain” — not just memory but also social and motor development, Gómez said.

Mary A. Carskadon, director of the Chronobiology and Sleep Research Laboratory at Bradley Hospital in East Providence, RI, called the trial “well presented and a good theory” that draws on a multitude of previous research. But like Gómez, she thinks “there are probably other things going on,” like a genetic process.

“What explains individual differences in this process, and how much is it neurobiology and how much is culture and environment?” she said. “The best kinds of theories are the ones that are floated like this and can be tested.” The next step would be to follow a group of children over time and measure their nap and memory.

“One of the most important takeaways is that we need to support napping in children,” Carskadon said.

Spencer fervently agrees with the need for more research and laments that so few examine the link between sleep and cognition in children. While many researchers study sleep disorders, “the function of healthy sleep, we don’t know much,” she said.

Felice J. Freyer can be contacted at [email protected] Follow her on Twitter @felicejfreyer.

Sharon D. Cole