I read today that overexposure to artificial light may actually increase a person’s chance of getting cancer. Yes, in recent studies by the Harvard Medical School and the University of Connecticut have reported that the incidences of cancer—colorectal and breast, in particular—are much higher in people deprived of darkness and/or overexposed to artificial light.

Some of you may have already heard that undue night illumination causes what many are calling light pollution. It’s that constant glow you see around cities that obscures the view of stars and other astronomical phenomenon. Astrologists, both amateur and professional, have been lobbying for restrictions on light pollution for years, especially since the founding of the International Dark Sky Association, which today has over 12,000 members.

Now, we can add to the list of darkness advocates health professionals and concerned citizens, too. The studies conducted by the universities noted about have demonstrated that women who work regular nightshifts and those who live in brightly-lit neighborhoods, are exposed to higher levels of artificial light. As a result, their bodies are not able to produce sufficient quantities of the hormone melatonin, an important hormone that has many functions, but for our purposes, is a significant factor in suppressing tumor development. What results are higher cancer levels in these individuals—73 percent higher in some cases!

Although this new research isn’t enough to prove that darkness is the key to a healthy body, it was enough to prompt the World Health Organization’s International Agency for Research on Cancer to add nightshift work to their list of suspected human carcinogens. That’s the first time I’ve heard of a work schedule—and not a tangible environmental toxin—be accused of increasing cancer levels in humans.

If lack of darkness can do this to humans, imagine what it does to wildlife. There are already some studies showing that night lights negatively affect the migration, mating, egg-laying, and feeding habits of myriads of species, including birds, frogs, insects, and even turtles. And the effects aren’t just minor. Every year, artificial lights cause the deaths of millions of birds.

But this alarming pattern isn’t like to change anytime soon, with increasing city expansion and our desire for well-lit cities. Yet it must if we are going to protect the environment, and ourselves.