It'll be alright on the night

Sleep helps us to learn new words, but children with reading comprehension difficulties often have poor memory for new vocabulary. In our recent study, we asked whether their vocabulary problems lie in what happens during sleep.

We taught children the names of unusual animals and plants. Some particular favourites were the shaggy komondor dog and the rainbow deglupta tree, pictured below¹. The words were split across two sets of learning and test sessions. In one set children learned the new words first thing in the morning, and in the other set they learned the new words at the end of the evening. Straight after each learning session, they completed some memory tests for the words they had learned. Children then sat the same tests again 12 and 24 hours later, allowing us to trace how their memory changed over wake and sleep.

Children were better at remembering the new words after they had slept. This memory boost lasted across the next day, even when children were tired again the following evening. Sleep was most beneficial when children learned the words right before their bedtime. In fact, when we visited again a month later, children were still better at remembering the words they had learned in the evening.

The children with reading comprehension difficulties found it harder to learn the new words. Even so, their memory still improved over sleep. Learning close to bedtime may be especially helpful for the children with a vocabulary weakness. Children with poor vocabulary were less likely to show sleep benefits for words learned earlier in the day. Nevertheless, all children showed sleep benefits for words learned in the evening.

So sleep is more than an opportunity for rest: it’s important for storing new words in long-term memory. Children with reading comprehension difficulties were equally able to benefit from sleep to retain their new knowledge, even though they found it harder to learn the words to start with. It may be that we can capitalise on sleep best if the information is fresh in our memory before we go to bed. This suggests that timing could play an important role in maximising learning – particularly for children with weaker vocabulary knowledge. For these children, a book at bedtime may be an especially valuable language learning opportunity.

This post was a summary of: Sleep-dependent consolidation in children with comprehension and vocabulary weaknesses: It’ll be alright on the night? James, Gaskell, & Henderson (2020), Journal of Child Psychology and Psychiatry. https://doi.org/10.1111/jcpp.13253 (open access)