There is mounting evidence that light can significantly impact human health and well-being by either entraining or disrupting circadian rhythms, depending on the time of day. For example, conventional blue pump LED light at night disrupts circadian rhythms and suppresses melatonin which is associated with an increased risk of obesity, diabetes and breast and prostate cancer. To meet this challenge there is a critical need to define the circadian spectral characteristics of light and to develop dynamic lighting solutions to address this health risk. Over the past 5-years, CIRCADIAN ZircLight has accomplished both tasks: creating evidence-based specifications for workplace circadian lighting, and developing specialized LED chips, control systems and luminaires for safe and healthy 24/7 lighting.

The work began in our medical research lighting laboratory, where the CIRCADIAN Light team led by Dr Martin Moore-Ede was awarded an NIH-SBIR grant to test different light-source spectra on subjects working 12-hour day and night shifts. While other research teams have researched short term exposure (up to 90 minutes) to monochromatic lights and found short wavelengths are much more potent than long wavelengths in suppressing melatonin, CIRCADIAN wanted to replicate normal workplace conditions. They studied freely moving human subjects under 540 lux polychromatic white light for 12-hour work shifts to more precisely define the circadian potent wavelengths under real world conditions

By using seven polychromatic white light sources with very different spectral power distributions and a medically relevant outcome (total overnight melatonin production, which is related to diabetes and breast cancer risk) they were able to derive a Circadian Potency curve for multiple hour white light exposure. Fortunately, they found the health problem is mostly confined to a narrow band of 440-490nm blue.

Using this Circadian Potency curve, CIRCADIAN Light has created and brought to market white LED lights which maximize Circadian Potency during daytime and minimize the disruptive effect of light at night. CIRCADIAN Light fixtures feature DynamicBlu™ Spectrum Control. The fixture automatically delivers blue rich light during the day and less than 2% blue light content at night based on time-of-day, location and season. The fixtures also feature a Zirc™ NightSafe™ LED - the first LED verified by the Underwriters Laboratory (UL) to emit less than 2% blue light (440-490nm) content at night.

In a 1-year case study conducted at a mission critical control room at a major energy company, the results included: a 50% reduction in excessive sleepiness, a 67% reduction in errors and mistakes, and 28% reduction in obese and overweight employees and less use of over-the-counter pain medications.


CIRCADIAN Light is a member of the worldwide CIRCADIAN® group of companies, bringing health, productivity and safety solutions to the 24/7 business workplaces around the globe. Born out of breakthrough research on human circadian clocks at Harvard Medical School, CIRCADIAN has led in the transition of medical science breakthroughs into the 24/7 workplace. We are unique in deeply understanding both the science, and the practical realities of 24/7 work.

For over 30 years, CIRCADIAN® has been the leading global provider of health, safety and productivity solutions to the 24/7 operations of over half the Fortune 500 and many other international companies. Our science-based solutions boost productivity, reduce errors and injuries, decrease absenteeism and employee turnover, and reduce health care costs.

Headquartered on Route 128, Boston's Technology Corridor, CIRCADIAN serves the 24/7 world, operating out of offices in North America, South America, Europe, Asia and Australia. Our mission is to make workplaces healthy, safe and productive for the 90 million people in critical jobs who work night and day shifts to give us our seamless 24-hour society.

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