The Good, the Bad, and the Time of Day of Bioactive Blue Light

The health risks of light at night. The Good, the Bad, and the Time of Day of Bioactive Blue Light.


Edison’s invention of the light bulb conquered the night, or so we thought. Now, the night seems to be striking back. On almost a regular basis, we see headlines extolling the harmful effects of artificial light at night. “Your smartphone is making you fat!” says one headline. “Light at night is contributing to the diabetes epidemic and increases your chance of heart attacks!” says another. “Working at night increases your chance of getting breast or prostate cancer by over 50%, and if you do get a cancer, the wrong light will prevent the chemotherapy from working.” A map of light at night exposure in Israel correlates with the map of increased rates of breast cancer in Israel. 

To make matters worse, exposure to the wrong light at night can lead to depression and mood disorders.
Individuals   who   work   rotating shifts feel as though they exist in a state of permanent “jet lag.” To add to the confusion, in areas where winters are long and dark, the lack of full spectrum bright light during daytime causes people to suffer Seasonal Affective Disorder (SAD) associated with depression and increased suicide rates.

In 2007 the World Health Organization’s (WHO) International Agency for Research on Cancer identified night shift light exposure and circadian disruption as a probable carcinogen, especially with breast cancer in women. WHO stated that the finding was consistent with “experimental studies [which] show that reducing melatonin levels at night increases the incidence or growth of tumors.” By 2012 sufficient data had accumulated for the American Medical Association (AMA) policy statement to go much further. The AMA confirmed that night time lighting exposure risks include “carcinogenic effects related to melatonin suppression, especially breast cancer.” They further added that other diseases that are exacerbated by nighttime light “include obesity, diabetes, depression and mood disorders, and reproductive problems.” In Europe, the continued accumulation of data on breast cancer risk has resulted in compensation payments from the Danish government to night shift workers who developed breast cancer.

To read the entire whitepaper, click here.
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