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Israeli researchers are reporting a link between exposure to artificial light at night (LAN) and elevated rates of breast cancer and prostate cancer. The 10-year study conducted by the University of Haifa's Biology Department confirmed suspicions that exposure to higher-intensity light during sleep can be dangerous. The results were recently published in the Chronobiology International journal.

More than 1,670 Israeli women took part in the study which found that those exposed to higher intensity light in their sleeping environment had 22 percent higher odds of developing breast cancer than those who slept in total darkness.

"Bulbs with high-intensity light contribute more to environmental light pollution, and lead to cancer," said researcher Professor Avraham Haim.

Study participants were asked about light in the bedroom from electrical fixtures, street fixtures outside the bedroom window, light from other rooms, and whether they went to sleep with the TV on.

The most significant predictor of breast cancer was exposure to artificial light in the bedroom.

"Artificial light is without doubt an irrevocable part of Western life, and its influence will only increase with the years . . . But fortunately, this environmental pollutant can easily be controlled," Haim told The Jerusalem Post.

The University of Haifa research paper corroborates findings from previous studies that showed artificial light as a source of obesity and cancer. But while previous studies focused on light in shopping malls and street light fixtures, the Haifa research centered on light at home, and especially in the bedroom.

In this latest study, the Israeli researchers theorized that LAN harms production of the hormone melatonin, which regulates other hormones and maintains the body's circadian rhythm. When it is dark, the body produces more melatonin; when it is light, the production of melatonin drops. The researchers showed that when the hormone is suppressed, the incidence of cancer rises.

The medical world already knows that women with breast cancer tend to have lower levels of melatonin than those without the disease.

Now, the Univeristy of Haifa researchers hope to raise awareness on the exposure to artificial light.