AMA warns against light exposure at night

University of Haifa researcher links over-exposure to cancer; AMA encourages further research into the matter.

July 17, 2012 00:38
2 minute read.
WOMAN reads in her room at night

WOMAN reads in her room at night 370. (photo credit: Thinkstock)


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The American Medical Association has issued an official statement warning against the health hazards posed by exposure to artificial light for hours at work or during sleep.

Prof. Abraham Haim of the University of Haifa’s Israeli Center for Interdisciplinary Research on Chronobiology has conducted research on the subject.

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“The fact that the AMA has taken this matter seriously and come to the conclusion that exposure to light at night is indeed a health hazard is a form of recognition for the various studies that experts such as Prof. Haim have been conducting over recent years,” the university stated on Monday. The AMA’s policy announcement supports Haim’s research conclusions, it said.

The AMA, the largest association of medical physicians in the US, recently announced its new policy recognizing adverse health effects of exposure to excessive light at night, including disrupting sleep, exacerbating sleep disorders and causing unsafe driving conditions.

The AMA encouraged further research into the matter.

The policy also supports the need for developing lighting technologies that minimize circadian (biological clock) disruption and encourages further research on the risks and benefits of occupational and environmental exposure to light at night.

Haim’s studies, published in peer-reviewed medical journals, include research that found that men who are exposed to artificial light at night have a higher risk of developing prostate cancer.

Haim published this finding in Chronobiology International.

Although the cause has not been proven conclusively, the study’s researchers suggested that repression of the production of melatonin hormone in the brain and weakening of the immune system because of light disruption at night of the biological clock – causing confusion between day and night – could be the explanation.

“The findings do not mean that we have to return to the Middle Ages and turn off all the lights at night,” the researchers said, “but night illumination should be taken into account in the planning of a country’s energy policy.”

The World Health Organization has already called artificial illumination at night a “source of pollution.”

In another study, Haim confirmed suspicions that exposure to artificial light at night, including at the workplace, is a risk factor for breast cancer. The retrospective study was carried out on 1,679 Jewish and Arab Israeli women and the level of light to which they were exposed in their bedrooms from street lamps outside the window, another room or night lights in the room.

Even the light of a TV set was examined as a factor. Almost half contracted breast cancer.

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