Sleep-Deprived Neurons May Shut Down, Even When You’re Awake
- By Brandon Keim
- April 27, 2011 |
- 3:24 pm |
- Categories: Brains and Behavior
When deprived of sleep, parts of the human brain may doze off, secretly snatching moments of slumber even as people seem to be awake.
That could explain why our sleep-deprived selves are so cognitively challenged: we are, if not exactly half-asleep, partially asleep.
“After a long period in an awake state, cortical neurons can go briefly ‘offline,’” wrote researchers led by University of Wisconsin neuroscientists Vladyslav Vyazovskiy and Giulio Tononi in a study published Apr. 27 in Nature. “Although both EEG and behavior indicate wakefulness, local populations of neurons in the cortex may be falling asleep, with negative consequences for performance.”
To study the rats’ neurology, Tononi’s team wired their brains to an EEG machine, kept them awake longer than usual, and looked for patterns in readouts of their brains’ electrical activity.
They found that scattered neurons throughout the rats’ brains gradually alternated between periods of activity and inactivity — a pattern associated with deep sleep, not wakefulness. But unlike their synchronization during sleep, these oscillations were brief and disjointed.
When the researchers tested the rats in a sugar pellet-reaching task, performance declined in proportion to their neurons’ “offline” status, suggestive of how sleep-deprived people have trouble functioning.
In a commentary accompanying the findings, University of California, Los Angeles neuroscientist Christopher Colwell wrote that this piecemeal, neuron-by-neuron descent into sleep squared with other research observations.
Sleepwalkers, for example, seem to inhabit “a twilight state between sleep and wakefulness,” wrote Colwell. Many animals also alternate between shutting down their brains’ left and right hemispheres, allowing for rest while maintaining vigilance.
“These observations also suggest that single neurons can move into a rest state,” wrote Colwell. “The ability to control behaviour actively with some neural circuits while others may be idling could be evolutionarily advantageous.”
However, Colwell cautioned against assuming that the patterns seen by Tononi in rats are responsible for short-slept human grouchiness, distraction and poor judgement. For now that’s “arguably an intellectual stretch,” he wrote — but the the data supports further investigations.
“And although it is only anecdotal evidence,” Colwell concluded, “I could swear that some of my students can sleep with their eyes wide open.”
Image: Flickr, McKay Savage.
See Also:
- Sleep Quality May Be Tied to Covert Brain Wave
- Sleep Hacking Produces Results ? For a Time
- All-Nighters Make Bodies Hoard Calories
- Sleepwalkers Replay Day's Learning
- The Uncertain Science of Sleep
- Jet Lag May Cause Stupidity
Citations: “Local sleep in awake rats.” By Vladyslav V. Vyazovskiy, Umberto Olcese, Erin C. Hanlon, Yuval Nir, Chiara Cirelli & Giulio Tononi. Nature, Vol. 472 No. 7344, April 28, 2011.
“Sleepy neurons?” By Christopher Colwell. Nature, Vol. 472 No. 7344, April 28, 2011.
Brandon is a Wired Science reporter and freelance journalist. Based in Brooklyn, New York and Bangor, Maine, he's fascinated with science, culture, history and nature.Follow @9brandon on Twitter.
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