Do children who sleep more retain more words?

By Ana Paula Yin and Shiyun Wang

This is a summary of: Axelsson, E. L., Williams, S. E., & Horst, J. S. (2016). The effect of sleep on children’s word retention and generalization. Frontiers in Psychology, 7. doi:10.3389/fpsyg.2016.01192

The Conventional Wisdom

As a kid, have you ever wondered why we were encouraged to nap in between activities in preschool or why we couldn’t use assigned nap times to do more activities? In fact, wouldn’t we learn more if we designated nap time to activities? According to the National Sleep Foundation, I’m afraid that might not be the case; sleep is just as important as feeding and hygiene to children. Conventional wisdom says that “sleep is the golden chain” and that “it binds health and our bodies together.” It is not by chance that a significant part of conventional wisdom supports the promotion of healthy behaviors. A substantial portion of them is related to sleep, acknowledging its importance for our universal well-being. 

Why Do We Even Sleep?

Nevertheless, why do we even sleep? Sleep is related to the brain’s healthy development and functioning (Dahl, 1999; Siegel, 2005; Hill et al., 2007; Galland et al., 2012). Moreover, sleep aids children with significant benefits (Touchette et al., 2007; Fondell et al., 2011; Jansen et al., 2011). Studies have revealed that sleep enormously enhances language acquisition during early development. 

Study on Napping

A study by Williams and Horst (2014) illustrates that children of age 3 recall more words read to them from storybooks if they nap soon after being introduced to the terms than if they do not rest. Researchers presented the same stories and different stories to test the implications of sleep on children’s facility to hold onto new words. Some children had the same stories read to them three times, while others had three different stories. Both conditions received the same amount of exposure to the selected words throughout the reading phase. Exposure to different stories is a case where learning becomes more complicated than exposure to the same story repeatedly (Horst et al., 2011). As seen in the figure below, the presentation of words right before children’s nap time was especially beneficial for children exposed to the new terms that came from different stories compared to words that came from the same stories. The findings demonstrate that taking a nap shortly after reading permitted children who encountered this obstacle of being exposed to different stories to succeed just as well as peers who stayed awake and heard the same stories. Furthermore, the advantage of napping shortly after was prolonged for seven days after listening to the words. As such, sleeping right after exposure to novel information improves memory (Talamini et al., 2008; Payne et al., 2012).

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Other researchers have shown that sleep deprivation disturbs the parts of the brain associated with executive functions, such as tasks assessing attention, memory, and alertness (Goel et al., 2009). Less than an hour restriction in children’s sleep for three days was enough to display worse executive function performance (Raviv et al., 2003). Considering that, sleep deprivation can impair the capability to absorb novel information (Axelsson, Williams, & Horst, 2016). Most importantly, since word learning is a gradual process that takes place progressively (McMurray et al., 2012; Bion et al., 2013), regular naps pose important ramifications for the retention of novel words in the long term.

But, Why is Sleep so Important for Children’s Word Retention?

First, what is word retention? Word retention is one’s potential to identify and accurately signal a word that has already been seen in a context different from the context where the term was initially heard (Axelsson, Williams, & Horst, 2016). Now, what could account for the consolidation of novel information during sleep? Researchers have approached this using the Active System Consolidation Theory (ASC), which implies that during sleep, memories become activated to be consolidated (Born & Wilhelm, 2011). According to the ASC theory, sleep is considered an active state (Dement and Kleitman, 1957). During sleep, memory-related to novel words are replayed in the brain, allowing biological events to transfer newly encountered information into long-term memory (Axelsson, Williams, & Horst, 2016). Sleep benefits children’s retention of new words by facilitating word-related memory consolidation. 

Advice for Parents and Teachers:

The studies on the effect of napping in word retention pose a responsibility for preschools to place naps during school hours. Concerns have been raised that preschools lower nap times and increase curriculum instruction (Kurdziel et al., 2013; Mednick, 2013). It is crucial to address these studies’ findings to health professionals, educational policymakers, and parents (Staton et al., 2016). With that in mind, guaranteeing that children are supported by an organized schedule consisting of naps and sleep suited to their age is crucial. An organized program avoids implications on novel word retention and their efficiency to function in new educational settings.

Recommendations for total daily sleep by age, by the National Sleep FoundationRecommendations for total daily sleep by age, by the National Sleep Foundation

Recommendations for total daily sleep by age, by the National Sleep Foundation


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