When I was working on Eastern Standard Tribe, my editor Patrick Nielsen Hayden told me that he thought that the electric light was a kind of drug, the kind of thing it takes a civilization a century to absorb, a hundred-year-long interregnum like the industrial century that Russian staggered through under the influence of vodka, or the lowlanders' gin-soaked hallucinogenic century. The ability to work when the sun was down, to ignore the seasons' rhythm that we'd been guided by since we were photosynthesizing single-celled organisms — it's the kind of thing that can and does drive us all mad. (David Marusek, a brilliant sf writer who lives in Alaska, once described whole towns of people from away that would crop up during the summer season — hoteliers and waiters and loggers and gas-station attendants — none of whom had ever seen the midnight sun, staying awake for days on end, brawling and hallucinating and screwing their brains out, like a Bosch illustration).
Now there's a theory that breast cancer is related to hormone imbalances caused by artificial lighting. Our ability to best our meat and bend it to our will is overstated, I think — the meat always gets its own back.
Their theory that artificial light can cause breast cancer is simple. Prolonged periods of exposure to artificial light disrupt the body's circadian rhythms – the inner biological clocks honed over thousands of years of evolution to regulate behaviors such as sleep and wakefulness. The disruption affects levels of hormones such as melatonin and the workings of cellular machinery, which can trigger the onset of cancer, Stevens theorizes.
"Mankind has only been exposed to these light sources for 150 years or so," Stevens said.
So far, the theory is based largely on suggestive, but inconclusive, observational studies. For instance, night-shift workers such as nurses tend to be more prone to develop breast cancer than day-shift workers, and blind women are less likely to have breast cancer than women with sight.