A new consensus survey confirms that human circadian clocks are highly sensitive to blue wavelengths—found in most of the lights sold today—and insufficient daytime blue-rich light and excessive blue-rich light at night, leads to many health disorders.

The research, published in Frontiers in Photonics, notes that the lights are linked to conditions such as sleep disorders, obesity, diabetes, and breast cancer as they are blue-enriched LEDs, which play havoc on people’s circadian rhythms.

“Fewer than 0.5% of lights sold today protect circadian health by altering their blue content across day and night. People should purchase lights for evening and night use that do not contain blue light and use blue-enriched LEDs during daytime only,” says lead author Martin Moore-Ede, MD, PhD, director of the Circadian Light Research Center and a former professor at Harvard Medical School, in a release.

248 scientists, with a total of 2,697 peer-reviewed publications on light and circadian clocks since 2008, completed a survey with potential consensus statements. The study reports a scientific consensus on:

  • Robust circadian rhythms are essential for maintaining good health.
  • Disrupting circadian rhythms can cause ill health.
  • Light at night causing circadian disruption increases the risk of breast cancer, obesity and diabetes, and sleep disorders.
  • 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.

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