They are built in to the central nervous system, but are influenced by ÒzeitgebersÓ such as the EarthÕs mag  netic field and the rising and setting of the sun.
In humans, they characterize body temperature, urine formation, oxygen consumption, cell division, endocrine secretions, and the sleep cycle. They are built in to the central nervous system, but are influenced by ÒzeitgebersÓ such as the EarthÕs mag  netic field and the rising and setting of the sun. When disturbed, they enter Òfree-runningÓ periods ranging from 21 to 27 hours apiece, but in general operate on a daily cycle. FTP, what are these rhythms, whose name comes from the Latin for Òapproxima  tely a dayÓ?
In humans, they characterize body temperature, urine formation, oxygen consumption, cell division, endocrine secretions, and the sleep cycle.
circadian rhythms