TL;DR
Deep sleep has its own slow electrical waves, and they can travel across the brain. A UC Berkeley study of older adults found that in people with more tau, the protein that forms the tangles of Alzheimer's, in the front of the brain, those waves traveled shorter distances and moved more on their own. The researchers call them "lonely waves," and the people who had more of them remembered fewer word pairs learned the day before. The finding is a link, not proof of cause, and it reaches us through a news report on the paper rather than the paper itself. It points somewhere hopeful all the same: if the sleeping brain's waves reflect tau, a night of wearing scalp sensors could one day become a cheap early signal for Alzheimer's, and better-connected deep sleep a target for treatment. To see our odds on a bedtime check for Alzheimer's, and the timeline of breakthroughs that could lead there, subscribe.
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