There's another mystery: Why did so few people dream about the maze? Fewer than 10 percent of those who took naps did. By contrast, Stickgold said, about 86 percent of those who played an Alpine racer skiing game dreamed about it, he said.
Maybe the game "is not rich enough, not compelling enough," he said. Future research, he said, will try to figure out why that is.
For now, though, at least one brain researcher who is familiar with the study is unimpressed with the findings.
"There is no convincing evidence that sleep has any effects on consolidating memory," said Irwin Feinberg, a professor in residence who studies sleep at the University of California at Davis. Sleep clearly isn't necessary for people to remember things, he said.
But Stickgold said that's a misunderstanding of his research. "No one in the field suggests that you need to sleep to learn things or retain memories," he said.
The National Sleep Foundation has details on sleep.
SOURCES: Robert Stickgold, associate professor, psychiatry, and director, Center for Sleep and Cognition, Harvard Medical School, Boston; Irwin Feinberg, M.D., professor in residence, University of California at Davis; April 22, 2010, Current Biology, online
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