As established, repetitive practice is necessary for knowledge retention. Sleep is also a contributing factor to new learning and memory consolidation.
In this study, Dr. Mazza and the team of researchers recruited 40 participants ages 18-29 from University of Lyon, who were randomly assigned to one of two groups. For this study, participants were asked to remember 16 Swahili-French words pairs. Participants completed a series of questionnaires and surveys to test sleep quality, level of sleepiness, and long-term and short-term memory capacity. Participants in the control group performed the learning session at 9:00 p.m., slept, and then performed a recall session 12 hours later. The experimental groups differed in whether they slept between the learning and relearning sessions.
During the first learning session, participants were shown word pairs for 7 seconds each. Then, the correct pair was displayed for 4 seconds if the translation was wrong. During the relearning session, all participants, but the controls, had to recall the translations with feedback, similarly to the learning session. The non-control participants practiced the translations until they successfully recalled all translations. All participants performed a cued-recall task without feedback over set time intervals in six months. In the learning sessions, non-controls were not significantly different in successful recalls at the first retrieval attempt. However, the number of remembered word pairs after 12 hours was higher for those who had slept than those who stayed awake.
Participants in the wake group needed more list trials to reach the learning criterion than the sleep group (p< .001). One week later, the sleep group forgot little, while the wake group suffered. Six months later, the wake group still did worse than the sleep group.
The results of this study confirm the idea that sleeping after learning is beneficial for consolidating memory. For future replications of this study, groups could contain more participants to make the results as generalizable as possible.
- S. Mazza, et al., Relearn Faster and Retain Longer. Psychological Science 7, 1321-1330 (2016). doi: 10.1177/0956797616659930
- Image retrieved from: https://pixabay.com/en/sleep-sleeping-asleep-1389978/