It is widely known that cats always land on their feet. For the most part, and not through purposeful testing, we've found this to be true. Could there be a correlation between the amount a cat sleeps and their quick reflexes to assure safe landings? Perhaps. And perhaps that's why new studies are showing that taking a nap a day can improve one's afternoon performance.
Feb. 22, 2010 -- Devote your lunch hour to a restful nap, and you may perform and learn better in the afternoon, a new study suggests.
Nappers performed better than non-nappers on a test, says study researcher Matthew Walker, PhD, an assistant professor of psychology at University of California, Berkeley. He presented his findings this week at the annual meeting of the American Association for the Advancement of Science in San Diego.
''The brain's ability to learn information is not stable across the day," Walker tells WebMD. The area of the brain that stores memories may get ''clogged up'' as the day goes on, akin to a full email in-box on your computer, he says.
Napping at midday, when the brain's ability to learn may have deteriorated, may clear the brain's memory storage area and make room for new information, Walker says.
Nap or No Nap: The Study
Walker and his colleagues gave 39 healthy young adults, average age 21, a difficult learning task intended to tax the brain's hippocampus, a region that helps store memories based on fact. The test -- learning 100 face-name pairs and then matching them up -- was given at noon.
Then, at 2 p.m., the nap group was given the chance for a 90-minute siesta; the no-nap group was asked to stay awake.
At 6 p.m., Walker gave them the test again. "People in the group which didn't nap had a slight reduction of about 10% in their learning capacity during the day,'' Walker tells WebMD, ''whereas the people who had a nap in between the first time they tried to learn relative to the second time they tried to learn actually improved their ability to learn by 10%."
The total time the participants slept during the 90-minute window didn't matter much in their later performance, Walker found. But the greater the amount of stage 2 non-REM sleep, a lighter form of non-dreaming sleep, the better their performance, he found.
Naps and Learning: Implications
The study results suggest that sleep before learning may be important, too, just as experts have known that sleep after learning is crucial to solidify information learned, Walker says.
In previous research, Walker and others found that fact-based memories are stored temporarily in the brain's hippocampus, then sent to the area known as the prefrontal cortex -- which he suspects has more storage space.
''Perhaps what happens is that the hippocampus is actually the short-term way station for memory in the brain," Walker tells WebMD. The hippocampus is good at getting hold of information, but at some point needs to ''download” the information to the pre-frontal cortex, he says.
The nap before learning may help clear out the hippocampus and send the data on to the prefrontal cortex, allowing new information to soak in, Walker says.
''What is new and exciting about this study is, he's shown that sleep, in addition to helping the memory consolidation process, also primes the brain to learn new information," says Jessica Payne, PhD, an assistant professor of psychology at the University of Notre Dame in Indiana, who has also researched the topic.
''Memory really has three stages,'' she says. They are:
- Initial memory encoding, after you learn something new
- Memory storage or consolidation
- Memory retrieval
Most of the sleep research has focused on the consolidation process, she says, although the new study looks at how sleep affects the initial encoding.
The new study findings, Payne says, may be of particular help for aging people who feel their memories are failing. A brief midday nap may help them learn and remember later in the day, she says.
Walker and Payne concede that a 90-minute nap in the middle of a workday isn't feasible for many people. But it may turn out that briefer naps would provide the same, or similar benefits, Payne says.