The study results also help explain the previously accepted idea that practice helped improve a skill, said Paul Reber, an associate professor of psychology at Northwestern and co-author of the study. Though this concept was acknowledged, researchers didn't know exactly why practice made perfect, he said, but this study's results show the process can be influenced even while sleeping.

It is important to remember the study does not suggest someone can learn new information while sleeping, Reber said. But the process could be useful to help the brain "do a better job of remembering things that are really important," he said.

Though the researchers have not developed any tools to assist in memory based on these results, Reber said he has thought of a few potential applications of the information, including supplementing students' learning of a new language by listening to an audio recording of previously introduced lecture notes while sleeping.

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