Lighting Innovations Driven By Medical Science

The Circadian Light Center serves as our medical research facilities for developing lighting technology. It is here, in our own in-house 24/7 workplace simulation center, that we set out to define the exact wavelengths of the light spectrum that would be healthy for people during the day, and those wavelengths that would be healthiest to see at night.

The scientific breakthroughs which created CIRCADIAN® Light studied people working real world schedules of multiple 12-hour day and 12-hour night shifts under white light, and sleeping during the night or the day -- just like millions of shift workers do every day in the real world. This turned out to be a revolutionary way of discovering the best and healthiest light for day and night. Let me explain why.

Natural and electric white light is polychromatic – it is made up of a rainbow spectrum of many carefully balanced colors. The lighting industry has created hundreds of ways to produce polychromatic white light each with a different spectral balance of colors. But different types of white light which may appear identical to the human eye, may have very different effects on our health and well-being depending on the spectral mix of color wavelengths which are used to create white light. Indeed, it is fair to say that many secrets of human health and productivity lie in the light spectrum.

But the scientists who made the initial discovery of the circadian bio-active wavelengths – the colors we need to tightly regulate in day and night lighting - did not use white light. Instead they used an ophthalmological device where subjects with pupil dilating drops in their eyes stared into a light box emitting monochromatic (single) color light. But people cannot tolerate for long staring into a light box with their chins on a stirrup– so all our previous knowledge on the circadian bio-active wavelengths was based on exposing people to single monochromatic colors for no longer than 60-90 minutes.

CIRCADIAN Research Unveils Precise Bio-Active Spectrum of Light in Real World Conditions

These opthamology laboratory studies were so unlike real world conditions that we decided to explore the circadian bioactive light spectrum in a different way. So, we asked what if we conducted medical, performance and psychological tests on volunteers working and freely moving under a wide variety polychromatic white lights? Could we tease out the circadian bioactive spectrum that actually operates in the real world?

Throughout the studies in the CIRCADIAN Light Center, conducted over multiple years with many types of white light spectra, our team of scientists regularly analyzed the volunteers’ blood, saliva and urine, looking for a variety of markers. These included glucose tolerance tests for diabetes and measuring melatonin - the cancer suppressing hormone. We also recorded sleep EEG patterns, assessed blood pressure at regular intervals, and analyzed people’s work performance and alertness under a wide variety of lighting solutions.

Circadian Light Center:
Medical Studies

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For example the Figure above shows that performance (reaction time) can be maintained at day time levels throughout the night shift under the CIRCADIAN Night Light spectrum. Normally at night reaction time progressively gets longer and performance gets worse as the night shift progresses. But under CIRCADIAN Light this did not happen.

This research not only identified the precise spectrum for good quality light and human health and performance, but also guided us in the design of innovative LED light chips. We hired LED chip designers and phosphor experts to work to craft, according to our specifications, the perfect light spectrum emission. By progressively testing and optimizing these proprietary LED chips installed in fixtures in the CIRCADIAN Light Center, we established that we could obtain a fivefold difference in the biological impact of white light in the 3000-4000K range on markers such as melatonin release. In other words it was not the CCT (Coordinated Color Temperature) that mattered most in controlling health outcomes. Instead it was the precise spectral power distribution and the intensity of the light.

The color components in the white light spectrum provided by our day and night LEDs vary across day and night, dawn and dusk to control precisely the dosage of bio-active blue that is delivered.

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