Young children sleep to learn

Lars Plougmann,, CC BY 2.0
Lars Plougmann,, CC BY 2.0

Rebecca Gómez likes sleep. More specifically, she likes studying how sleep affects language learning in young children. Gómez, Principal Investigator at the Child Cognition Lab at the University of Arizona, has spent her career figuring out how young children learn, and it turns out sleep has a lot to do with it. Her first experiments with sleep and learning were just a side project based on a colleague’s suggestion. But that side project led her to one of the most surprising findings of her career.

In a 2006 Psychological Science study, Gómez and her colleagues exposed 15-month-old infants to a made-up language that had a simple grammatical pattern. They found that if the children napped after hearing the language, they were later able to recognize the language pattern even when new words were introduced. “It was as if they retained a rule that they were able to apply to new stimuli,” says Gómez.

But this didn’t happen for the kids who didn’t nap. They were able to recognize the exact words they had heard before, but couldn’t extend that knowledge to new words. In a 2009 Developmental Science follow-up study, Gómez showed that if these abilities were tested 24 hours after hearing the language, kids who napped held on to the ability to generalize the grammar to new words while kids who didn’t nap forgot everything.

What this said to Gómez was, “It’s obvious that sleep is playing an important role.” And that role has to do with memory consolidation. Researchers like Gómez have found that memories and knowledge learned throughout the day are strengthened during sleep, an effect that’s controlled by neurons in the brain.

Naps are important for learning

As Gómez explains, a lot of what we know about sleep and learning comes from animal studies. In rodents, for example, we can record a neuron firing while the animal performs a specific task, and oftentimes, that neuron will fire in the same way while the animal sleeps. “It’s this neural replay that we think is stabilizing the memory,” says Gómez. And that’s true for infants, adolescents, and adults.

“I really think that the way sleep helps infants is very different from the way it helps older children.”

But the relationship between sleep and learning in young children isn’t always so clear. Gómez notes her 2014 Child Development study that showed napping actually hindered two-and-a-half-year-olds’ abilities to generalize their learning. But she believes the finding says more about which memory was being retained rather than if it was being retained. The nap reinforces what’s being learned while the child is awake. So, if the nap is taken before the child has really grasped the lesson, it may reinforce memories from earlier stages of learning when the rule they’re being taught isn’t fully understood yet.

Gómez is currently finishing a follow-up study that clarifies this work and the beneficial role naps have for children this age. “I really think that the way sleep helps infants is very different from the way it helps older children,” says Gómez, “This wasn’t something I would’ve predicted.”

Future work

Gómez’ current research is focused on elucidating how learning and memory fare during the phase where young children begin to transition out of naps. She’s also working on a long-term study that will test children across a range of ages – from infants to five-year-olds – to track how the mechanisms involved in sleep consolidation develop. “That would help us understand more about the role of sleep in infancy compared to the role of sleep in toddlers and preschoolers,” says Gómez.

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