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Surprising Science

Our Neurons Nap While We’re Awake

The divide between sleep and wakefulness may not be as clearcut as we thought. Recent research shows that in visibly awake rats, some areas of the brain’s cortex go “offline”.

What’s the Latest Development?

A team of neuroscientists at the University of Madison-Wisconsin have found that the longer a rat stays awake, the more of its neurons start to take naps, even though the rat is still capable of reacting to its environment. “The rats were awake, but awake with a nice sprinkling of localized sleep in the cortex,” says Guilio Tononi, lead author of the study. “By recording the activity of many small populations of neurons, Tononi and his colleagues showed that OFF states occur randomly throughout the cortex when a rat has been awake for a long time.”

What’s the Big Idea?

Dr. Tononi notes that compared to the global phenomenon we recognize as sleep, the presence of localized OFF neurons [in rats] ‘is more insidious because we can’t tell it’s happening’. In humans, this could explain why sleep deprivation can impair judgment. “These findings suggest that scientists may have had an overly simplistic idea of waking and sleep states. ‘If these both happen—local sleep during waking and local waking during sleep—then it may lead to a rethinking of our concepts of sleep states,’ says Peter Achermann, a sleep researcher at the University of Zurich in Switzerland.”


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