NOT TOO BRIGHT

Even if you're not religious, you've no doubt heard that in the Bible, God declared, But did the Almighty really mean "Let there be superbright 300-watt blue LED light all night long wherever you go"? Unlikely, considering what this may be doing to our health.

- BY MERYL DAVIDS LANDAU

We've all had the experience of hanging out at home—reading, watching TV, scrolling through social media—and then glancing out the window, surprised to find that it's gotten pitch-black outside. Or being out at night—say, at a shopping plaza or a ball field—and, in the dazzling lights, forgetting that it's evening.

We don't even think about such experiences because we're so used to them. And of course electric lights are great for allowing us to get stuff done after dark (and decorating our houses at this time of year to get into the holiday groove). But a growing body of research is finding that when we're exposed to too much light at night, it can have serious ramifications for our health.

Light pollution is defined as any excessive or inappropriate use of electrical light that alters natural patterns of darkness. This doesn't mean all light in the evening is bad—that's prime reading time, and streetlights keep people safe. But too much light too close to bedtime (especially the wrong kind of light) can contaminate the air and our health like smog-fueling chemicals.

That's because we're not built for it. The human body evolved for millions of years—eons before the lightbulb was a thing—with strict demarcation between light and dark, says John Hanifin, Ph.D., director of the Light Research Program at Thomas Jefferson University. “Early humans had huge contrasts between bright light in the daytime and complete darkness at night, but today we live in a world of poorly lit days inside and a night home environment that's very bright,” he says.

Though there are gaps in the research, especially with regard to how much badly timed and too-bright light is too much, the science on light pollution's myriad risks is exploding.

Your body on light