The researchers completed two memory experiments. In the first experiment, the participants learned 40 sets of words. In the second experiment, the participants learned a series of finger signals. In the two experiments, only half of the participants were told to take the test after 10 hours. All participants on the above will be tested. Only some participants are arranged to take a nap between study and test. It turns out that participants in the sleeping group performed better than those who did not sleep, and participants who were told in advance to take the test also had higher test scores. 
Some participants who were told to take the test did not fall asleep during the nap, and they unconsciously reviewed what they had learned in their brains.
 the researchers believe that sleep helps the brain store to be useful in the future Memory information.