Cancer Risk Link to Night Time Light Exposure

World Light MapCIRCADIAN® ZircLight Developing Healthy Light at Night

by CIRCADIAN on Monday, August 04, 2014

CIRCADIAN® announced today that it has acquired controlling stake in ZircLight™ Inc., which holds the core intellectual property rights to LED lighting systems, eyewear and computer screen devices designed to alleviate the negative effects of artificial lighting in our nighttime environments.

The technological developments of CIRCADIAN ZircLight build upon a growing body of research showing that exposure to light at night causes a disruption of brain neuroendocrine systems, including melatonin and cortisol rhythms.

This research suggests that the myriad of health issues related to shift workers may be due to the nighttime light exposure during night shifts.

Health Effects of Light Exposure at Night

Mounting medical evidence led the World Health Organization to conclude in December 2007 that light exposure in night shift work is “probably carcinogenic to humans”.

Two years later in 2009, BBC News reported that the Danish government has begun paying compensation to women who have developed breast cancer after long spells working nights.

It was long thought that the harmful effects of shift work were caused by sleep deprivation. However, we now know that much of the adverse effect is actually related to circadian timing disruption caused by nocturnal light exposure.

The hormonal dysregulation found with nighttime light exposure is associated with fatigue, loss of alertness, vigilance errors and reduced performance in night shift employees.

Night shift light exposure also disrupts genetic disease markers and substantial evidence is building for increased health risks such as heart disease, diabetes, sleep disorders, and breast, prostate and colon cancers in night shift workers regularly exposed to light at night.

There is therefore a substantial dark side to the use of electric light at night.

Discovering the Culprit: Blue Wavelength Light

Recent research shows that the harmful effects of light at night are largely mediated by certain blue wavelengths which are detected by newly-discovered visual pathway that is especially sensitive to blue light.

Blue light during the day is critical to synchronizing our circadian rhythms, but we are not designed to see blue light at night.

Many of the adverse effects of chronic light exposure at night appear to be mediated by abnormal nighttime stimulation of this time-keeping pathway by the blue light wavelengths in the light spectrum.

When this pathway is disrupted by exposure to white light or only blue light at night, it initiates a chain reaction that results in decreased energy, mood, performance and vigilance and increased risk of errors, accidents, injuries, absenteeism and workplace turnover.

Over the long- term, continuous light exposure at night may result in sustained hormonal dysregulation leading to significant health consequences including sleep disorders, diabetes, heart disease, depression and even certain types of cancer (e.g., breast, prostate and colon cancers).


CIRCADIAN® ZircLight™ is developing spectrum-specific circadian-modulated ZircLight LED lighting, filtered eyewear and display screens to provide a highly effective solution to nocturnal workplace lighting that directly based on the mechanisms underlying the light-induced dysfunction.

Working with partners who are leaders in LED lighting and light sensors and controls, we are bringing a healthy revolution to how light is used at night.

Extensive peer-reviewed published work in animals and humans by Dr. Robert Casper and his team at the University of Toronto, protected by issued worldwide patents owned by CIRCADIAN ZircLight, showed that filtering out specific wavelengths of blue light prevents many of the adverse health, safety and performance effects of night shift work.

CIRCADIAN Press Release

Learn more about CIRCADIAN’s acquisition of ZircLight™ by reading CIRCADIAN’s latest press release. Want to learn more about the science behind ZircLight™? Click here to learn more about ZircLight technology.

Disclosure: I am a Director of Circadian Australia

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