"Having a nap after learning might facilitate the capacity to utilise newly learned information in a new task," said Hua-Chen Wang, lecturer in the School of Education at Macquarie University.
"We found a positive nap effect on children's learning of letter-sound mappings, and in particular, using that knowledge to read unfamiliar words."
Thirty-two three-to-five-year-old children from two daycare centres in Sydney, Australia who napped regularly participated in the study. The daycare centres did not provide formal teaching of letter names or sounds.
Each child participated in seven sessions over two to four weeks which included the following:
Pre-test: To establish baseline levels of letter-sound knowledge.
Letter-sound mapping training: Held a week apart under both "nap" and "no-nap conditions."
Post-tests: To assess learning once after a nap and once after a period of wakefulness. To examine whether any effect of nap on learning was maintained, knowledge was also reassessed one day later. Each session assessed letter-sound mappings and using explicit learning and knowledge generalisation tasks.
The authors predicted that if a nap benefits letter-sounds skills, then children who napped would perform better on both the explicit learning tasks and knowledge transfer tasks.
The findings showed that napping did appear to positively affect performance on the knowledge transfer test. This nap benefit was maintained the following day.
The authors acknowledge that because the study was conducted at daycare centres instead of in a laboratory (to make the children more comfortable), they were unable to measure physiological features of sleep such as rapid eye movement (REM) and how they are related to the sleep benefits. This would be an important direction for future research.
The authors also note that since the nap effect was only found in generalising letter-sound knowledge to recognizing printed words, but not on the explicit learning measures, future research on this topic with larger sample size is recommended.
"The research provides initial evidence that naps facilitate the acquisition and application of letter-sound mappings, abilities that are crucial to early reading development," said Anne Castles, Professor of Psychological Studies at Macquarie University. "These findings may have implications for creating the optimal conditions for the acquisition of this fundamental literacy skill in preschool children."