Health & Medicine

Study supports the case for midday naps

So you've just had lunch and are sitting in class or at your office desk. And now you're fighting that overwhelming desire for a little nap. According to new research, a midday snooze would be the right thing to do. It can dramatically restore and even boost your brain power afterward.

Researchers at the University of California at Berkeley took a group of 39 healthy adults and divided them into two groups. All were given a rigorous learning task at noon designed to test their fact-based memories. Both groups performed at comparable levels on that test. Half of the group then took a 90-minute nap — long enough to go through a full sleep cycle. At 6 p.m., both groups were again given a round of tasks. In this case, the nappers performed significantly better and actually improved in their capacity to learn, according to the study.

Exactly why the nap effect works "is still a mystery," according to Berkeley assistant professor of psychology Matthew Walker, lead investigator of the study. "One theory is that particular types of brain-wave patterns that occur during sleep help change the storage locations of recently stored information from short-term to long-term, such that when you wake up, the short-term capacity for new memory formation is refreshed." He said the findings reinforce the researchers' hypothesis that sleep is needed to clear the brain's short-term memory storage — the hippocampus — and make room for new information.

"It's as though the e-mail inbox in your hippocampus is full and, until you sleep and clear out those fact e-mails, you're not going to receive any more mail. It's just going to bounce until you sleep and move it into another folder," Walker said in a statement.

The results build on a previous study by Walker and others that found that staying up all night (to study for an exam, say, or finish a big project at work) has a negative impact, decreasing the ability to recall crammed-in facts by nearly 40 percent, due to a shutdown of brain regions caused by sleep deprivation.

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