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During deep sleep, older people have less coordination between two brain waves that are important to saving new memories. “It’s like a drummer that’s perhaps just one beat off the rhythm,” says Matthew Walker, one of the paper’s authors and a professor of neuroscience and psychology at the University of California, Berkeley. “The aging brain just doesn’t seem to be able to synchronize its brain waves effectively.”

Author of the book Why We Sleep (not yet available in Portuguese), Walker explains that the study was the result of an effort to understand how the sleeping brain turns short-term memories into memories that can last a lifetime. “The brain seems to perform this elegant trick of cementing new facts into the neural architecture of the brain,” says the neuroscientist.

The study. 20 young adults who had to memorize 120 pairs of words participated. “We put electrodes on their head and we had them sleep,” says Walker. The electrodes let researchers monitor the electrical waves produced by the brain during deep sleep. The researchers focused on the interaction between slow waves, which occur every second or so, and faster waves called sleep spindles, which occur more than 12 times a second.

The next morning, the volunteers took a test to see how many word pairs they could still remember. And it turned out that their performance was determined by how well their slow waves and spindles synchronized during deep sleep.

Repercussion. The finding appears to answer a long-standing question about how aging can affect memory even in healthy people. “This is the first paper that actually found a cellular mechanism that might be affected during aging and therefore be responsible for the lack of memory consolidation during sleep, says Julie Seibt, a professor in sleep and plasticity at the University of Surrey, United Kingdom, who was not involved in the new study. But points out: “To confirm the finding, though, researchers will have to show that it’s possible to cause memory problems in a young brain by disrupting these rhythms, in a much broader and diverse sample.” Click here to read the full article.