As reported by the Arizona Republic, January 10, 2007.
Late Nights Confuse Hormone Processes
By Susan Brink, Los Angeles Times Reporter
Some cancers might be rooted in sleep deprivation - or, more
precisely, to too many hours exposed to artificial light, according to
Richard G. Stevens, cancer researcher at the University of Connecticut
Health Center.
His work is based on the theory that the increase in breast cancer in
the industrialized world is linked to the disruption of hormone cycles.
Light, he says, suppresses production of the hormone melatonin, which
allows levels of estrogen to rise. And, when lights are on long after
dark, it confuses women's circadian clocks, the roughly 24-hour internal
rhythm that keeps hormones and organs on their daily schedule.
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"Cells don't know when not to divide," he says.
His theory was bolstered by a 1991 Centers for Disease Control and
Prevention report showing that blind women are about half as likely as
sighted women to get breast cancer.
An Oct. 15, 2005, study in Cancer Research looked at sleep patterns
of more than 12,000 women. Although researchers found no statistically
significant increase in cancer risk among short sleepers, says Stevens,
an author of the study, the risk estimates were consistently lower in
long sleepers.
Until more is known, he advises women to get adequate sleep - and to
do it in a very dark room.
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