1. Biological Clocks in Infants and Children.Curt P. Richter, M.D.,* Johns Hopkins School of Medicine, Baltimore, Md.
Normal adults give evidence of harboring only 2 clocks—one the waking-sleeping cycle that measures time in units of 24 hours; the other the menstrual cycle that measures time in units of 28 days. Under pathological conditions, however, adults may give evidence of harboring a number of different clocks that measure time in units ranging from 12 hours to several years. For example one patient may show swelling of. the knees for 2 or 3 days every 13 days; another may show loss of all neutrophils every 21 days. In most adults only one clock may manifest its presence; but in some, several clocks—each measuring time in different units and quite independent of one another—may manifest their presence. The clocks may manifest themselves for weeks, months or years, or a lifetime—some through purely
HOLT LE, SHAW EB, RILEY CM, McKAY RJ. Transactions of the American Pediatric Society: Seventy-First Annual Meeting, Atlantic City, May 2 and 3, 1961. Am J Dis Child. 1961;102(5):682–781. doi:10.1001/archpedi.1961.02080010684006
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