Circadian Light Research Center Survey Confirms Harmful Health Effects of Blue-Enriched LED Light

The Circadian Light Research Center released the results of a consensus survey of 248 leading scientists, which confirms that human circadian clocks are highly sensitive to blue wavelengths, and exposure to insufficient daytime blue-rich light and excessive blue-rich light at night, leads to many major health disorders.

Lead author Martin Moore-Ede, M.D., Ph.D., director of the Circadian Light Research Center and a former professor at Harvard Medical School, said, "Fewer than 0.5% of lights sold today protect circadian health by altering their blue content across day and night. Many people in the lighting industry claim that the circadian science is not sufficiently mature to incorporate into lights. So, we asked the leading scientists who work on circadian rhythms and light whether they agreed."

The study titled Lights Should Support Circadian Rhythms: Evidence-Based Scientific Consensus was published online on Research Square, a preprint server, and submitted for peer-reviewed journal publication. It reports there was a scientific consensus on the following:

Robust circadian rhythms are essential for maintaining good health
Disrupting circadian rhythms can cause ill health.
Repetitive and prolonged exposure to light at night bright enough to cause circadian disruption increases the risk of breast cancer in women, increases the risk of obesity and diabetes and increases the risk of sleep disorders
There was also Consensus about the key role of the blue wavelengths in white light:
The most potent wavelengths for circadian entrainment are 460-495 nm blue light near the sensitivity peak of the ipRGC melanopic receptors
Blue-enriched light in the evening (during the three hours before bedtime) disrupts nocturnal sleep, phase shifts the circadian system and disrupts circadian rhythms
The blue content of light entering the eyes is much more important in determining circadian health outcomes than the correlated color temperature (CCT) of the light source.
The scientists also agreed that:
There is now sufficient evidence to support the widespread introduction of circadian lighting that adjusts light intensity and blue content across day and night to maintain robust circadian entrainment and health
Light used in the evening (during the three hours before bedtime) should have as little blue content as practically possible
LED lights with high 460-495nm blue content should carry the warning label "may be harmful if used at night"
Increasing lights' energy efficiency is desirable, but not if it increases the risks of causing circadian disruption and serious illness.
Professor Sean Cain of Monash University in Australia, an author of the study, said: "Exposure to blue-enriched LED light in the evening and night hours raises significant health issues because the human circadian system is highly sensitive to blue light near the 480 nm peak sensitivity of the melanopic intrinsically-photosensitive retinal ganglion cells (ipRGCs) in the human retina. Even small amounts of blue content in white LED light during nocturnal hours can cause circadian disruption and increase the risk of health disorders."