We’ve all been there. Sometimes the temptation to prolong an evening can just be too great. But on those occasions when we’ve slipped into bed past the witching hour, our next day’s work is peppered with a litany of careless errors.
As a study published in Nature reveals, the reason for this (the careless errors, not the previous late night) may be that parts of our brains are sleeping while our eyes are wide open.
At least, it seems to be that way with lab rats. In the Nature study, researchers kept rodents from nodding off by introducing novel items – colourful balls and boxes as well as “odorous nesting material from other rats” – into their cages.
The researchers found that as the experiment progressed and the rats became sleep-deprived, the electrical activity at specific sites in their brains was reduced. However the overall brain activity and their behaviour indicated that they were fully awake.
Small groups of brain cells in the cortex – the part of the brain associated with planning and complex functions – were in fact “offline” despite the animals still being mobile and active. This lack of activity in neurones (the most important brain cells) can be observed across the whole of the cortex during deep sleep. Here, it occurred at isolated and disparate locations.
Prof Giulio Tononi, principal investigator at The Centre for Sleep and Consciousness at the University of Wisconsin and a co-author of the paper, said that these knots of napping neurones
may be responsible for the attention lapses, poor judgment, mistake-proneness and irritability that we experience when we haven’t had enough sleep, yet don’t feel particularly sleepy.”
The sleeping brain cells certainly had an influence on the rats’ behaviour in this study. When neurones in the motor cortex – the part of the cortex associated with planning and execution of movement – went offline a split-second before rats reached for a sugar pellet, the rodents were much less likely to grab the goodies.
The sleeping neurone syndrome is yet to be observed directly in humans but it can tentatively be added to the separate phenomenon of “microsleep” – where people are fully asleep for several seconds without noticing – as a negative consequence of not getting a good night’s rest.
Looked at another way, though, the discovery could comfort the night owls among us; it seems that our brain cells can get the rest we deprive them of even when we’re awake.
Vyazovskiy, V., Olcese, U., Hanlon, E., Nir, Y., Cirelli, C., & Tononi, G. (2011). Local sleep in awake rats Nature, 472 (7344), 443-447 DOI: 10.1038/nature10009
Image credit: avantard (via Flickr)
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