Sleeping is the way to become a blacksmith: the effect of sleep on repeated learning.

Summary Objective The saying "practice makes perfect" illustrates that learning is enhanced by practice. When a material is learned repeatedly, each learning session is easier than the last, indicating an economy in relearning. Given the beneficial effect of sleep on memory consolidation, we wondered whether a night's sleep would promote this economy of learning by reducing the number of revisions required to acquire a set of verbal items. Methods Two groups of 20 young adults performed initial learning and then relearning of 16 words from the Swahili language and their translation into French. The number of learning trials required to recall the 16 words without error was measured. The two sessions were spaced 12 hours apart. One group did the learning session at 9:00 am and the re-learning session at 9:00 pm (Awakening group), the other learned at 9:00 pm and re-learned at 9:00 am after a night of sleep (Sleep group). Word retention was also measured one week later. Results The number of trials required to learn the 16 pairs was equivalent in the 2 groups (5.6 ± 1.9 vs. 5.2 ± 1.5 for the Sleep and Wake groups, respectively). When relearning 12 h later, participants who had slept started the test with better performance (10.3 words ± 2.6 vs. 7.4 words ± 3.1 . p p p p Conclusion Sleep thus allows for savings during relearning, while ensuring more effective long-term maintenance. Thus, interspersing a night of sleep between review sessions would allow for less review and longer retention.