Forget All-Nighters.(value of sleep)

Like many students, Kimberly Fenn has pulled more than a few all- nighters, cramming facts into her head for the next day's exam, fighting exhaustion and gravity to keep her eyelids from closing. Her parents always told her she'd be better off with a good night's sleep. But it was only this past year, as a psychology graduate student at the University of Chicago, that Fenn learned how true that was. She tested two groups of undergraduates on their ability to learn a gibberish language. One group (the crammers) had to take a test on the same day as their training, while another group (the sleepers) were allowed a night's rest. The results were startling. The sleepers scored higher than the crammers, "like going from F's to C's," says Howard Nusbaum, Fenn's adviser and a coauthor of the study.

The findings do more than merely confirm what we (or at least our moms) already knew. They suggest that the link between sleep and the brain's higher mental processes is far stronger than researchers previously suspected. Psychologists have long known that sleep enhances basic cognitive and motor skills, and they've shown that people tend to sleep longer after heavy mental workouts, like learning to program in Basic. Fenn's study suggests that the sleeping brain plays an essential role in turning the rush of daily events into long-term memories--not mere facts and images but elaborate mental processes, like how to tie your shoelaces or prove Pythagoras' theorem.

In her study, published last week in the journal Nature, Fenn had her undergrads learn a nonsense language. She started by playing a recording of a gibberish word ("nawn") while flashing its English equivalent ("lawn") on a screen. Then she continued to feed them other translations, like "frud" for "frog" and "snurt" for "smart." Finally, she tested them by giving them a gibberish word and asking them to figure out what the English equivalent should be. ...