Earlier research has found that dreams boost learning, with one study suggesting a 90-minute nap may help lock in long-term memories. But Walker’s research, published this week in the journal Current Biology, finds that another phase of sleep, called nonrapid eye movement (NREM) is most closely linked to the learning boost provided by a nap.
Walker and his colleagues recruited 44 volunteers — 27 women and 17 men — to come to the sleep lab at noon. First, the volunteers were given a task in which they had to memorize 100 names and faces. Then they were tested for how well they recalled the face-name matches.
Next, the researchers tucked half of the volunteers in for a nap between 2 p.m. and 3:40 p.m. The scientists measured the napping volunteers’ brain waves as they slept. The other group of participants stayed awake and did daily activities as they normally would. At 6 p.m., both groups memorized another set of 100 faces and names and were tested on their memory. (The experiment was set up so nappers had more than an hour to shake off any remaining fuzziness before the test, Walker said.)
The first major finding, Walker said, was that learning ability degrades as the day wears on. Volunteers who didn’t nap did about 12 percent worse on the evening test than they did on the morning test. (Walker presented preliminary findings of this effect at a conference in February 2010.) But shut-eye not only reversed those effects, it provided a memory boost: Napping test-takers did about 10 percent better on the evening test than they did on the morning test. In all, the difference in scores between nappers and non-nappers was about 20 percent, Walker said.
Secondly, the brain-wave monitoring turned up a likely culprit for the memory upgrade: a short, synchronized burst of electrical activity called a sleep spindle. These sleep spindles last about one second and can occur 1,000 times per night during NREM sleep. People who had more of these spindles, especially people who had more over a frontal area of the brain called the prefrontal cortex, showed the most refreshment in learning capacity after their nap, Walker said.
I love it when modern day research confirms the benefits of age old practices. Muslims have known, but mostly abandoned, the practice of sleeping after the midday prayer, even though it is an established tradition of the Prophet Muhammed (pbuh). Also, because of the ignorance of this in Western culture, most modern day offices don’t allow for such a practice to be maintained. The productivity gains and efficiency benefits could easily outweigh the cost of a 30 – 45 minute downtime in the middle of the day.