In Our Cellular Clocks, She’s Found a Lifetime of Discoveries

This morning, when the sun came up, billions of humans opened their eyes and admitted into their bodies a shaft of light from space. When the stream of photons struck the retina, neurons fired. And in every organ, in nearly every cell, elaborate machinery stirred. Each cell’s circadian clock, a complex of proteins whose levels rise and fall with the sun, clicked into gear.

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