When we sleep, our brain "recharges," but it definitely does not take a break from neural activity, according to a report in the newest issue of Science Times.

A test centered around object placement memorization was performed and the results suggested that over a span of 20 minutes, most people taking the test could ace the test, even when taking it a day later.

But, other correlations with the objects (which did not have direct comparisons and placement in the test) becomes hazy in the mind of many test takers. That is, until you sleep on it and re-take the test after some shut-eye. Perhaps the brain commits more of the memorization to memory once it's given time to "rest."