Sleep 11: Naps for better memory

Today while waiting for my plane to reach the magic 10,000 feet, I did some of my back reading in Scientific American. I was a little surprised when they were talking about what the next President should do. I thought, "Have they given up on Obama already?!" Then I realized I was reading the May 2008 issue.

Regardless, they reported a sleep study that may have shown that a 6 minute nap has a significant, positive impact on memory. This study, like many others, reinforces the idea that sleep is not a time for the brain to shut down. Rather, it is a time for the brain to engage in alternate information processing tasks when it's not distracted by things like the conscious world.

The subjects in Lahl’s study reported to the university’s sleep lab at 1 p.m. They were given two minutes to memorize a list of 30 words and tested on their recall an hour later. In the interim, they either stayed awake, took a six-minute nap or a longer snooze averaging 35 minutes. On no sleep, subjects recalled an average of just under seven words. A short nap raised performance to more than eight. A longer nap, including some time in deeper sleep, boosted recall to more than nine words.

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A sleeping brain is not merely on standby; it runs through a suite of complex and orderly activities. One of these is a flow of neural activity from the hippocampus, where short-term memories are formed, to the cortex, where they are stored in more durable forms—a possible reason people can remember things better on awakening. Nor is this process simply a matter of scribing data into neural tissue. Several recent studies of sleep and sleeplessness show that slumber is especially important for doing clever stuff with information, such as extracting the gist of what has been learned, combining facts in interesting ways and dealing with the day’s emotions.

“Executive thinking is particularly impaired by sleep loss,” Horne says. “You become much more blinkered in your thinking, less able to deal with novelty and less able to evaluate risk.” This is bad news for medics, shift workers and military commanders, he observes, and perhaps explains why casinos stay open all night.

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Not everyone agrees, and the article does cite some skeptics of the study.

It's a reasonably short article and accessible to the non-scientist reader. You can see the whole thing here.