‘Artificial light in bedroom predictor of breast cancer'

The reduced production of the hormone melatonin seems to interfere with the division of cells, which is one of the mechanisms that are harmed in cancer.

January 18, 2011 07:05
2 minute read.
‘Artificial light in bedroom predictor of breast cancer'

light bulb 88. (photo credit: )


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When your partner insists on turning down the lights in your bedroom, he is not only in a romantic mood – he is also worried about reducing your risk of breast cancer.

A new study at the University of Haifa has confirmed suspicions that exposure to artificial light at night, including at the workplace, is a risk factor – in fact, the “best predictor” – for breast cancer – as it has already been shown to be one for prostate cancer in men.

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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.

They were controlled for medical and family history, socioeconomic status, alcohol usage, number of children and other factors.

The team headed by Prof. Avraham Haim with Prof. Boris Fortunov of the university, Prof. Hedy Rennert of the Technion- Israel Institute of Technology and Dr. Itai Klug, who earned his doctorate based on this research, which has just been published in the journal Chronobiology International.

Previous studies have pointed to a connection to breast cancer risks and exposure to artificial light, but these had been based on light from street fixtures and shopping malls and during shift work at night. The new study focuses on light at home, and especially in the bedroom where they sleep for hours at end.

The elevated risk is not due to working late at night per se, but apparently stems rather from exposure to artificial light for long periods during these hours. The reduced production of the hormone melatonin seems to interfere with the division of cells, which is one of the mechanisms that are harmed in cancer.

The participants were asked about light in the bedroom from electrical fixtures and from street fixtures and other rooms, as well as whether they went to sleep with the TV set turned on.

They were asked to rate the amount of light to which they were exposed in the bedroom – none, a little, quite a lot or completely light. The most significant predictor of breast cancer was exposure to artificial light in the bedroom.

Another factor in Jewish women was whether they had given birth and to how many children. Arab women, who on average have more children than Jewish women, were at a lower risk of breast cancer.

When the researchers studied exposure to artificial light in the bedroom only among Jewish women, the significance was even stronger than with Arab women included.

Artificial light is without doubt an irrevocable part of Western life, and its influence will only increase with the years, the researchers said. But fortunately, this “environmental pollutant” can easily be controlled,” concluded Haim, who added that awareness of the risk should be increased.

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