Researchers at the University of Chicago used a test that involved learning to play video games. The study, published in Learning and Memory, showed that people who had "forgotten" how to perform a complex task 12 hours after training found that those abilities were restored after a night's sleep.

"Sleep consolidated learning by restoring what was lost over the course of a day following training and by protecting what was learned against subsequent loss," Howard Nusbaum said in a statement. "These findings suggest that sleep has an important role in learning generalized skills in stabilizing and protecting memory."

The researchers tested about 200 college students, who had little previous experience playing video games. The team had students learn video games in which players must use both hands to deal with continually changing visual and auditory signals.

"We showed that if after learning, by the end of the day, people 'forgot' some of what was learned, a night's sleep restored this memory loss," Nusbaum said.