"We examined whether people in the REM sleep group had better memory for what they saw in the morning than the non-REM or quiet rest group, and there was no difference in memory between the three groups," says Mednick. "So it looked as though, even though there was no difference in memory, the people in the REM group were more able to utilize information from the morning to answer their creativity problems in the afternoon."
Mednick says during REM, information can flow freely among different brain networks involved in learning and memory.
"Specifically, with REM sleep, there seems to be information flow between an area called the hippocampus, which is very important for learning or (episodic) memories of our own experiences… and the neocortex, which is more for the associative processes," Mednick explains.
She says this research supports the hypothesis that "during REM sleep, you actually have a change in the transfer of information from the hippocampus to the neocortex, and it actually shuts down the hippocampus. And so you have this free-flowing information system in the neocortex where these new associations can be made without necessarily knowing that they're from some sort of experience in your life. They're just now becoming part of an associative network."
"This is very similar to what occurs during dreams," she says. "You have these kind of fanciful dreams, very bizarre, you can't quite figure out how these different ideas are connected. But it's likely that this is the same process."
The research builds on research by Mednick and others revealing the benefits of napping, which prompted her to write the book, Take a Nap! Change Your Life.
Mednick, who tries to nap at least three times a week amid her hectic schedule, points out that only naps longer than 60 minutes will have REM sleep.
Her personal reaction to this new result was to try it on herself.
"I've been studying naps for a long time and have shown so many different levels of improvement in memory and different kinds of performance with napping, but when I first got this result for the REM sleep… I actually decided I was going to give it a test of my own," she reports.
In my free time, I write songs, and I decided I was going to write a new song… and I was going to use a nap. And I thought about what the song was, and the words I wanted to have in there, and I was decided to take a 90-minute nap. When I woke up, in fact I had the song ready," she says.
"This is something that, anecdotally, you hear a lot about people who've been working on a problem, they put it aside, they go they take a nap or they fall asleep… and suddenly they have this insight. And I thought, great, I got to experience that!"
This research was published in PNAS early online edition for the week of June 8 - 12, 2009, and was funded by the National Institutes of Health (NIH).
Elsewhere on the Web:
Napping Tips for Students from UC Davis
"Midday Snooze May Lower Heart Risk"