Lead investigator Matthew Walker, an assistant professor of psychology at the University of California, Berkeley, also found the more hours people spend awake, the more sluggish the mind becomes.
The results support previous data from the same research team that showed pulling an all-nighter decreases one's ability to cram in new facts by nearly 40 percent because some brain regions shut down during sleep deprivation.
The study involved 39 healthy young adults divided into two groups -- nap and no nap. At noon, all the participants were subjected to a rigorous learning task intended to tax the hippocampus, a region of the brain that helps store fact-based memories. Both groups performed at comparable levels.
At 2 p.m., the nap group took a 90-minute siesta while the no-nap group stayed awake. At 6 p.m., participants performed a new round of learning exercises.
Those who remained awake throughout the day became worse at learning; those who napped did markedly better and actually improved in their capacity to learn.
The findings were presented at the annual meeting of the American Association of the Advancement of Science in San Diego.
