[tz] Time zones, daylight saving, and cancer risk
eggert at cs.ucla.edu
Sat Nov 11 09:51:16 UTC 2017
In 2011 Mikhail Borisenkov of the Komi Science Center in Syktyvkar, Russia
reported that latitude and longitude can affect cancer rates. In particular he
found that in Russia, position within a time zone explained 15% of the
variability in female breast cancer mortality.
Similar results have now been reported in the US. Neil Caporaso and colleagues
at the National Cancer Institute in Bethesda, Maryland recently found a
significant association between time zone position and cancer incidence. They
estimated that the risk of breast cancer is 12% higher at the western extreme of
a US time zone compared to the eastern extreme. Other cancers show similar (but
A plausible explanation is that ill-timed light increases cancer risk by
disrupting circadian rhythm. This effect has been known for some time in other
respects: for example, blind women have a significantly lower risk for breast
cancer, possibly because melatonin offers a protective effect and nocturnal
exposure to visible light suppresses melatonin secretion. This is currently an
active area of research: the 2017 Nobel Prizes in Physiology or Medicine went to
Perhaps we should not take Ben Franklin's "early to bed and early to rise"
advice to an extreme, as daylight saving time (or more generally, moving time
zones eastward) can significantly increase cancer risk.
Stevens RG. Breast cancer risk higher in western parts of time zones; is
electric light to blame? The Conversation. 2017-10-19.
Gu F, Xu S, Devesa SS et al. Longitude position in a time zone and cancer risk
in the United States. Cancer Epidem Biomarkers Prev. 2017-08-01;26(8):1306-11
Borisenkov MF. Latitude of residence and position in time zone are predictors of
cancer incidence, cancer mortality, and life expectancy at birth. Chronobiology
Int. 2011-01-13;28(2):155-62. http://dx.doi.org/10.3109/07420528.2010.541312
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