Naps help some preschoolers to learn, but may hinder learning in children with Down syndrome

A growing body of research has established a link between sleep, improved learning and memory consolidation in children and adults. Yet, a new study done at the University of Arizona shows that napping may not be universally beneficial.

The researchers found that even though napping can help young children, usually developing ones, to learn, this can have the opposite effect on children with Down syndrome, a population in which disorders of the memory and sleep disorders are common.

The results, published in Proceedings of the National Academy of Sciences, are among the first to show that naps can actually increase memory loss in some populations.

"In children with Down syndrome, taking a nap right after learning seems to keep them from keeping information, which is totally different from what happened in developing children. typical who benefited from this nap, "said Jamie Edgin, senior lecturer in psychology and senior author of PNAS paper.

The study involved 24 typical developing children, approximately 2.5 years on average, and 25 children with Down syndrome, averaging approximately 4.5 years. The children had equivalent performance on basic cognitive scales.

The first author of the study, Goffredina Spanò, PhD student in the Department of Psychology of the AU, visited young participants at their home, where she taught children new words as well as unpublished objects images. Researchers coined words such as "tobe", "wame", "bope" and "neek" to make sure that they were unknown to all participants, but they were designed to structurally mimic the words that we could meet in English. language.

During several home visits, the researchers tested the retention of new words by children at varying intervals: five minutes after learning the words; four hours after learning the words and remaining awake; four hours after learning the words and taking a nap shortly after learning them; and 24 hours later to test long-term retention.

Children in typical development best remember the new words four hours and 24 hours after their learning if they take a nap of about 90 minutes shortly after learning. If children with Down syndrome were napping after learning the words, retention was much worse at four-hour and 24-hour intervals than they did not nap.

More research is needed to understand why naps affect learning differently in both populations, but rapid eye movement, or paradoxical sleep, may play a role, Edgin said. More and more literature has shown that paradoxical sleep, which is reduced in Down syndrome, can work in conjunction with slow wave sleep, which is the deepest phase of slow sleep, to help consolidate memories. .

Down syndrome is often accompanied by significant sleep problems, including sleep apnea and transition difficulties between different stages of sleep. In this study, 44% of children with Down syndrome did not sleep at all during their nap, while only about 6% of typically developing children failed to achieve REM sleep. The researchers studied the sleep stages during the nap by performing a polysomnography at home, which records the biophysiological changes that occur during sleep. They measured overall sleep quality via a wrist activity monitor and sleep diaries kept by the children's parents.

"There may be a problem with the lack of REM sleep and the fact of not completing this EMN step, which could be related to retention problems," Edgin said. "Some recent studies suggest that patients show lower retention if they just get a little REM but they have a whole EMR cycle." There is still a lot to be done, but paradoxical sleep needs to be taken into account. "

All of the children in the study were habitual diapers, that is, they regularly took a nap at least four times a week. The tests were conducted in children's homes, taking into account their regular nap schedules.

"We were very careful not to deprive children of sleep, so the waking condition was fulfilled at a time when they were not usually taking a nap," said Spanò, PhD in Psychology's In 2016 and now a postdoctoral researcher. at University College London. "We were also trying to assess sleep more ecologically in a natural and familiar environment – their homes – instead of being in a laboratory where they might not feel as comfortable. "

Findings of the researchers could have implications for pharmaceuticals and other interventions under development for people with Down syndrome, said Edgin, who is also co-director of the program on cognition and neural systems of the United States. UA and director of the development laboratory and memory disorders.

"Clinical trials often do not consider sleep as an important factor in the design of the trial," she said. "If we can show that children learn differently when they nap, it shows how important healthy sleep is."

Edgin's lab is continuing its work on an ongoing project to limit naps in children with Down syndrome as a possible intervention.

Explore further:
Study Reveals Naps Can Help Preschoolers Learn

More information:
Goffredina Spanò el al., "REM sleep during nap is related differently to memory consolidation in preschoolers and children with Down syndrome," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1811488115