How rhythms become a vital part of us
the Guardian -

Whether it’s the physiological monthly cycle of a woman or a plant’s seasonal cycle, the external world influences biology

This column has run weekly for more than two years but, from a biological perspective, that is a bizarre rhythm. Cells and systems in the brain and body have built-in mechanisms to enforce a 24-hour sleep-wake cycle. And light-sensitive cells in the eye and elsewhere keep that synched to the earth’s rotation.

Animals and plants regulate their activities on an annual cycle,...


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