Naps Make You Smarter

A good night's sleep is crucial to storing knowledge learned earlier in the day — that much was known. Now, a new study finds that getting shut-eye before you learn is important, too.

Volunteers who took a 100-minute nap before launching into an evening memorization task scored an average of 20 percentage points higher on the memory test compared with people who did the memorization without snoozing first.

"It really seems to be the first evidence that we're aware of that indicates a proactive benefit of sleep," study co-author Matthew Walker, a professor of psychology and neuroscience at the University of California, Berkeley, told LiveScience.

"It's not simply enough to sleep after learning," Walker said. "It turns out you also need to sleep before learning."

Refreshing naps

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.

Uploading memories

Walker and his colleagues suspect that the sleep spindles are working to transfer information from the hippocampus, a small area deep in your brain where memories are made, to the prefrontal cortex, which serves as long-term storage. That frees up the hippocampus to make new memories, Walker said.

"It's almost like clearing out your informational inbox of your e-mail so you can start to receive new e-mails the next day," he said.

NREM sleep and sleep spindle frequency change throughout a person's life span, Walker said. Older people, for example, have a decline in sleep spindles, suggesting that sleep disruption could be one reason for the memory loss prevalent in old age. The volunteers in the current study were young, but the researchers hope to investigate the effect of sleep spindles on learning in older adults, Walker said.

The research also draws attention to the importance of sleep, Walker said. Sleep spindles happen more frequently later in the night, precisely the time people cut short when they rise early for work and school, Walker said.

"Somewhere between infancy and early adulthood, we abandon the notion that sleep is useful," Walker said. That needs to change, he said: "Sleep is doing something very active for things like learning and memory. I think for us as a society to stop thinking of sleep as a luxury rather than a biological necessity is going to be wise."

Study: Reverse Alzheimer

By Agence France-Presse, Updated: 1/7/2010

Long suspected of causing brain tumors, mobile phones are now being eyed as key allies in the fight against Alzheimer's disease, US researchers said in a study.

Long suspected of causing brain tumors, mobile phones are now being eyed as key allies in the fight against Alzheimer's disease, US researchers said in a study.

Researchers at the University of South Florida (USF) found, to their surprise, that 96 mice they zapped twice daily for an hour each time with electromagnetic waves similar to those generated by US mobile (cellular) phones benefited from the exposure.

Older mice saw deposits of beta-amyloid -- a protein fragment that accumulates in the brain of Alzheimer's sufferers to form the disease's signature plaques -- wiped out and their memories improved after long-term exposure to mobile phones, the study published in the Journal of Alzheimer's Disease showed.

Young adult mice with no apparent signs of memory impairment were protected against Alzheimer's disease after several months' exposure to the phone waves, and the memories of normal mice with no genetic predisposition for Alzheimer's disease were boosted after exposure to the electromagnetic waves.

No one was more surprised by the results than the researchers themselves, who had embarked on the tests several years ago, convinced they would show "that the electromagnetic fields from a cell phone would be deleterious to Alzheimer's mice," lead author Gary Arendash, a USF professor, told AFP.

"When we got our initial results showing a beneficial effect, I thought, 'Give it a few more months and it will get bad for them.'

"It never got bad. We just kept getting these beneficial effects in both the Alzheimer's and normal mice," Arendash said.

It took several months of exposure before the benefits were seen in mice, and that would be the equivalent of many years in humans, Arendash said.

The mice in the study didn't wear tiny headsets or have scientists holding mobile phones up to their ears. Instead, their cages were arranged around an antenna that generated a mobile phone signal.

Each animal was housed the same distance from the antenna and exposed to electromagnetic waves equivalent to what is typically emitted by a mobile phone pressed up against a human head.

"Since we selected electromagnetic parameters that were identical to human cell phone use and tested mice in a task closely analogous to a human memory test, we believe our findings could have considerable relevance to humans," Arendash said.

But William Thies, chief medical and scientific officer of the Alzheimer's Association, said the study was "very preliminary" and warned against self-medicating by over-using a cell phone.
"No one should feel they are being protected from Alzheimer's, dementia, cognitive decline by using their cell phones based on this study," Thies said in a statement.

The study "needs to be replicated in animals before we begin to even consider trying it in people, as animal models of Alzheimer's and people with the disease are very different," he said.

Arenbach called the Alzheimers Association reaction disappointing and "so negative about a new research area of neuroscience that could offer real benefits against the disease in the future -- especially since a new therapeutic approach is desperately needed and long overdue."

The researchers concurred that more research is needed to find out, among other things, what the optimal "dosage" of electromagnetic waves would be -- the 918 megaHerz in US mobile phones, 800 megaHerz in European phones, or another frequency -- and how long effective "treatment" would have to be.

"If we can determine the best set of electromagnetic parameters to effectively prevent beta-amyloid aggregation and remove pre-existing beta amyloid deposits from the brain, this technology could be quickly translated to human benefit against Alzheimer's disease," said USF professor Chuanhai Cao.

The new therapy could also be used to treat one of the invisible injuries suffered by soldiers in war, Cao said.

"Since production and aggregation of beta-amyloid occurs in traumatic brain injury, particularly in soldiers during war, the therapeutic impact of our findings may extend beyond Alzheimer's disease," he said.

Around 36 million people will be living with dementia this year, according to international umbrella group Alzheimer's Disease International.

Pentagon officials have said that up to 360,000 US veterans of Iraq and Afghanistan may have suffered brain injuries.