Too much artificial light at night from gadgets and lamps could be bad for health and is even linked to cancer, say doctors
AMA says further research needed into possible link between artificial light and cancer



15:28 GMT, 22 June 2012

Artificial light is essential for modern societies to function, but doctors fear our 24/7 culture could have unintended consequences for human health.

The American Medical Association has just voted to accept the recommendations of a report that recognises exposure to light from street lamps to TV screens is linked to sleep disorders.

The AMA added that is supported further study into the possible link between keeping lights on all the time with cancer and obesity, as well as exacerbation of chronic diseases such as diabetes.

Light exposure is far higher now due to our 24/7 culture and reliance on technology

Artificial light exposure is higher now than ever due to our 24/7 culture and reliance on technology

Cancer epidemiologist Professor Richard Stevens from the University of Connecticut, said: 'It is a recognition by a major health body, the American Medical Association, that this is an emerging environmental issue that has a potentially large impact on the health of society.

'Based on an accumulation of evidence, this august body is now making the statement: ‘We take this seriously, and the public should take it seriously too.'

Professor Stevens is credited with being the first to articulate the hypothesis that the increasing use of artificial light at night may be related to the high breast cancer risk in the industrialized world.

'There’s no question that this light at night changes our physiology in the short term,' Stevens says.

'We know that artificial light disrupts circadian rhythms. We’re learning more and more about the specifics of what that means. The clearest evidence is about the hormone melatonin. We’re lowering it, we’re even suppressing it completely, depending on the amount of light.'

Melatonin has been shown to inhibit breast cancer in laboratory rats.

Stevens is careful to say that the changes in human physiology from artificial light, circadian disruption and melatonin suppression have not been proven to cause breast cancer. Instead he offers a judicial analogy:

'It’s guilty in a civil trial, but no verdict in a criminal trial. A reasonable jury would say there is a preponderance of evidence, but it’s not beyond a reasonable doubt at this point.'

The adoption of the AMA council report’s
recommendations by the association could mean more federal funding for
studies into the health impact of
artificial light at night.

Five years ago, the cancer research arm of the World Health Organization declared night shift work as a 'probable carcinogen.'