Why Sleeping Shrinks Your Brain

If you haven't yet read Ariana Huffington's The Sleep Revolution or been otherwise inspired/terrified/shamed into reevaluating your sleep habits, there's no time like the present. We already know that a full night of sleep is essential for so many of our bodies' weird and wonderful recharging processes. We also know that sleep deprivation — even just one night — can wreak havoc on those processes and our system as a whole. But just when we thought we'd heard everything about the myriad benefits of those magical eight hours, it turns out that sleeping actually causes our brains to shrink. Weirder yet: That nightly neural downsizing is a (really) good thing.

LiveScience reports that a new study from the University of Wisconsin-Madison Centre for Sleep and Consciousness found that sleep allows the synapses in our brains to shrink by about 20%. No, that doesn't mean we're losing brain cells or thought capacity; the shrinking of those neural connections happens because our brains are finally getting the rest — the researchers call it "renormalisation" — they so desperately need.

"Sleep is the perfect time to allow the synaptic renormalisation to occur," explains study co-author Chiara Cirelli, MD, PhD. "Because when we are awake, we are 'slaves' of the here and now, always attending some stimuli and learning something...During sleep, we are much less preoccupied by the external world...and the brain can sample [or assess] all our synapses, and renormalise them in a smart way."

Without that shrinking and "renormalisation," the synapses can hit max capacity in terms of brain traffic. At that point of information overload, our abilities to learn, adapt, and retain memories are not functioning as they should be — something you've likely experienced if you've ever pulled an all-nighter. Suddenly, "head shrinker" has a whole new (slightly more pleasant?) ring to it. So do your brain a favour and let it drop a size or two tonight.

Struggling to nod off? Ariana sings the praises of a hot bath before bed — and silk pyjamas, of course. Otherwise, we hear a camping trip can work wonders for your internal clock (maybe save the silks for your indoor sleeping adventures, though).
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