Our brains don’t rest when we sleep. Electrical waves ripple through our noggins as our neurons talk to each other. Now, researchers have shown that when these waves don’t interact properly, we can lose our long-term memory. The work may help explain why older adults are so forgetful, and it could lead to new therapies to treat memory loss.
To find out how sleep contributes to memory loss in old age, Randolph Helfrich, a neuroscientist at the University of California (UC), Berkeley, and his team gave healthy 70- and 20-year-olds a memory test. Participants were trained to match 120 common, short words—for example, “bird”—with nonsense words made of combinations of random syllables, like “jubu.” Once they learned the word-nonsense word combos, the volunteers played a version of the game “memory.” They had to match the word pairs twice: once about 10 minutes after they’d mastered the task, and again a few hours after waking from a full night’s rest. While they slept, researchers recorded the electrical activity in their brains.