Researchers found that memory rehearsal during sleep can help you to remember things for a long time.
Journal of Neuroscience
In this study, researchers worked with the volunteers and asked them to remember the locations of the objects on a computer screen. A value given to each object informed participants how much money they could make if they remembered it later on the test.
“The pay-off was much higher for some of the objects than for others,” explained Ken Paller, professor of psychology at Northwestern and co-author of the study. “In other words, we manipulated the value of the memories — some were valuable memories and others not so much, just as the things we experience each day vary in the extent to which we’d like to be able to remember them later.”
Researchers presented the objects to the participants along with a sound in both the states of wakefulness and sleep. They found that the participants remembered the associations better when the sound presentations occurred during sleep.
“We think that what’s happening during sleep is basically the reactivation of that information,” Delphine Oudiette, lead author of the paper and the postdoctoral fellow in the department of psychology at Northwestern, said in a statement. “We can provoke the reactivation by presenting those sounds, therefore energizing the low-value memories so they get stored better.”
Many of the memories of the daytime are not remembered. On the other hand, “Whatever makes you rehearse during sleep is going to determine what you remember later, and conversely, what you’re going to forget,” said Paller.
“We think one of the reasons for that is that we have to rehearse memories in order to keep them. When you practice and rehearse, you increase the likelihood of later remembering,” Oudiette said. “And a lot of our rehearsal happens when we don’t even realize it — while we’re asleep.”
“The in-between time is what we want to learn more about, because a fascinating aspect of memory storage is that it is not static,” Paller said. “Memories in our brain are changing all of the time. Sometimes you improve memory storage by rehearsing all the details, so maybe later you remember better — or maybe worse if you’ve embellished too much.
“The fact that this critical memory reactivation transpires during sleep has mostly been hidden from us, from humanity, because we don’t realize so much of what’s happening while we’re asleep,” he said.
Oudiette, D., Antony, J., Creery, J., & Paller, K. (2013). The Role of Memory Reactivation during Wakefulness and Sleep in Determining Which Memories Endure Journal of Neuroscience, 33 (15), 6672-6678 DOI: 10.1523/JNEUROSCI.5497-12.2013