Human-Centric Lighting in the Workplace: It's not just about color temperature

While it might make sense to turn up the Kelvin settings during the day and down toward night, it's not always that simple. MARK HALPER discovers the virtues of spectral power and natural light at offices from coast to coast in the US.

As our modern lives emphatically defy the planet's natural day/night cycle we are, plainly put, messing with our bodies' circadian clocks. Our physiology has evolved over millions of years to conform with 24-hour patterns of sunrise and sunset, yet our contemporary non-stop work and play habits fight brutally against that conditioning.

And there is perhaps no greater symbol of our new clock-defying norm than electric light, which has generally kept the gates wide open to nocturnal land for well over a century in the developed world.

Many efforts are now underway to study the impact of light on the circadian rhythm, and how to engineer lighting systems to be good circadian citizens. Those efforts are intensifying now that LED lighting has arrived. LEDs' digital nature makes them relatively easy to tune to settings that might support circadian needs.

"There are certain wavelengths in the blue part of the spectrum that boost alertness, performance, and mood during the daytime hours, but during the nighttime hours they disrupt circadian clocks and now have been shown through hundreds of research studies to cause a 65% increase in breast cancer, a 37% increase in diabetes, a substantial increase in cardiovascular disease, an increase in prostate cancer, and a variety of medical problems," said Moore-Ede. The list of risks goes on, including diabetes related to blue's instigation of insulin resistance, and obesity connected to blue's stimulation of appetite.

It almost sounds as though LEDs at night are the new tobacco.

But it doesn't have to be that way. Moore-Ede's company, Circadian Light, makes a suite of office lighting products including ceiling lights, troffers, and suspended fixtures that cut out the harmful, bio-active blue frequencies at night. Circadian's system, based on LED chips from Plessey, "delivers a timed dosage, and independently varies the bio-active blue content," Moore-Ede explained.


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