Fred Davis

Daily rhythm disruptions linked to fertility problems

A simple experiment of leaving a room well-lit until midnight instead of turning off the lights at 6 p.

m. cut the fertility rate of lab mice by half – leading some researchers to wonder what effect shift work, all-nighters and other sleep disruptions might have on humans trying to conceive.Researchers at Northwestern University disrupted the   circadian rhythms   of female mice for five to six days after they mated with male mice. One group of 18 mice got an extra six hours of light; another 18 mice lost daylight.By the end of the experiment, only half of the mice with extra daylight had litters. Mice that lost daylight fared worse – only 20 percent gave birth. Yet 90 percent of a control group of mice gave birth. These control mice had been exposed to a steady 12 hours of daylight, according to the study published today (May 23) in the journal PLoS ONE.Mammals, and even trees, are known to synchronize their internal clocks, which control metabolism and other functions, to cues of nigh...

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