In a recent study, participants did activities including word recall tasks, locating objects, and reproducing sequences of finger taps, in an effort to discover the effect sleep would have on these memories later.
Participants who were told they’d be tested on the tasks later remembered them better than those who didn’t think they would be tested after about 7 to 8 hours of sleep. People who weren’t allowed to sleep didn’t show any improvement in remembering the tasks, whether or not they thought they’d be tested.
This study basically shows that sleep selectively enhances memories that you expect to need in the future, according to CNN.com.
