The researchers completed two memory experiments in which participants at number one school learned 40 sets of words, and participants at number two school learned a series of finger signals. In both trials, only half of the participants were told they would be tested in 10 hours, when virtually all were. Only some of the participants were allowed to nap between study and test. The sleepers performed better than the no-sleepers, and those who had been told they were taking the test did better. 
In the second school some of the nap participants the exam with a relaxed attitude and achieved better results.
 researchers believe that sleep helps the brain store information from memories that will be useful in the future.