
A pianist made sleeping-time shorter and made practicing-time longer.
But he was not able to become better pianist.
Then he made sleeping-time longer, and he was able to become better pianist.
Also two babies were taught how to use a toy, and one baby took a nap, and other baby did not take a nap.
And after a few hours, a baby who took a nap has memorized toy's use way, but a baby who did not take a nap has not memorized it.
In short, when sleeping-time is longer, memory ability becomes better.










