Naps, Learning and REM

It's a shame that we stop encouraging naps in preschool. After all, there's a growing body of scientific evidence that the afternoon siesta is an important mental tool, which enhances productivity, learning and memory. (It's really much more effective than a cup of coffee.) Here's the Times:

Have to solve a problem? Try taking a nap. But it has to be the right kind of nap -- one that includes rapid eye movement, or REM, sleep, the kind that includes dreams.

Researchers led by Sara C. Mednick,