July 21, 2016 | David F. Coppedge

Sleep on It: Housekeeping Night Crew Works Swing Shift

Why do we sleep? A new theory identifies a vital purpose for those seemingly lost hours.

During the day, we all collect vast quantities of information through our senses. Not all of it is useful, but if we don’t condense it to essentials, memories can be like piles of clutter in a hoarder’s house.

Evidence announced by New Scientist supports the “housekeeping” theory of sleep. Clare Wilson says that the “mystery of what sleep does to our brains may finally be solved.”

It is one of life’s great enigmas: why do we sleep? Now we have the best evidence yet of what sleep is for – allowing housekeeping processes to take place that stop our brains becoming overloaded with new memories….

Support is growing for a theory that sleep evolved so that connections in the brain can be pruned down during slumber, making room for fresh memories to form the next day. “Sleep is the price we pay for learning,” says Giulio Tononi of the University of Wisconsin-Madison, who developed the idea.

Experiments with rats showed smaller synapses after sleep, potentially allowing room for new memories. Other observations support the idea.

If the housekeeping theory is right, it would explain why, when we miss a night’s sleep, the next day we find it harder to concentrate and learn new information – we may have less capacity to encode new experiences. The finding suggests that, as well as it being important to get a good night’s sleep after learning something, we should also try to sleep well the night before.

It could also explain why, if our sleep is interrupted, we feel less refreshed the next day. There is some indirect evidence that deep, slow-wave sleep is best for pruning back synapses, and it takes time for our brains to reach this level of unconsciousness.

It took 4 years of study to identify the brain tissue responding to sleep, Wilson says.

The Creator thought of everything. Imagine! While your conscious mind is mostly off, your body’s night crew knows what to do and springs into action.

Sleep is usually a pleasurable part of life, taking up nearly a third of our lifetimes. Enjoy it, but don’t over use it. “Love not sleep, lest you come to poverty,” Solomon warned. Give the housekeeping crew enough time to work but not to loaf.


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  • John C says:

    So hopefully we discovered coffee and other stimulants before sleep ‘evolved.’ It beggars credulity as to how this even becomes a consideration among evos.

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