Elizabeth Weise at USA Today put it succinctly in her lede: "Researchers know that sleep deprivation makes people and animals less functional. Now a team of researchers in Wisconsin and Italy has found that in rats kept awake past their bed times, their brains begin to turn themselves off, neuron by neuron, though the rat is still awake."
So, in rats at least, individual neurons (oddly floating in a void in the artist's conception above) know when they need some rest and voluntarily catch some Zs whenever they need to. (How's that for teleological anthropomorphizing?) As Weise notes in her second graf, the first neurons to go offline are the ones used most during the day. She quotes the scientists saying that this is worrisome because it means that, if the same thing happens in people, even though we are still awake and thinking that we can function normally, we are working without the help of many of the neurons on which we depend during the better part of the day.
Stephanie Pappas at CBSNews.com fearlessly extrapolates directly to humans in her lede, protected by that most overused word in science and medical writing, "may": "If you're staying up past your bedtime, you may not be as awake as you think you are."
The findings, published in this week's Nature, were based on experiments on rats with fine-wire probes into various parts of their frontal cortexes, each probe reading electrical activity in a single neuron or a small group of connected neurons. As the animals were kept from sleeping by such things as distracting them with toys, some of the neurons went quiet for long periods.
Tina Hesman Saey, writing at Science News, gives a useful bit of background, saying that the old paradigm of sleep held that some kind of central control center told the whole brain when to sleep. "But," she writes, "researchers have been building a case for the past two decades that sleep may originate in single cells and eventually spread all over the brain."
Ed Yong has a nicely colloquial account of the experiments at Discover's blog, "Not Exactly Rocket Science." Almost alone among the English-language stories, Yong's attributes the work to the Nature paper's first author, a post-doc who almost surely did the real work, rather than to the lab chiefs cited in most other accounts. That's smart, and more science writers should do it.