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Sensitivity of the circadian system to evening bright light in preschool‐age children

We found robust melatonin suppression (87.6 ± 10.0%) in response to the bright light stimulus. Melatonin levels remained attenuated for 50‐min after termination of the light stimulus (P < 0.008). Furthermore, melatonin levels did not return to 50% of those observed in the dim light condition 50‐min after the light exposure for 7/10 children.

Color-Changing LEDs Could Reset the Circadian Rhythm - The Atlantic

In much the same way as the ear allows us to both hear and stay balanced, the eye’s rods and cones supply us with vision while these novel intrinsic photosensitive retinal ganglion cells, or ipRGCs, perform a separate function: They sense the quality and quantity of light, with input from the rods and cones, and send that information to a master circadian clock in the brain. That clock then conducts a symphony of cellular timepieces throughout the body, ensuring they all “rise and fall with appropriate relationships to the others,” explains Berson.

Study links night exposure to blue light with breast and prostate cancer: Researchers used images taken by astronauts to evaluate outdoor lighting in Madrid and Barcelona -- ScienceDaily

Results obtained for both cities show that participants exposed to higher levels of blue light had a 1.5 and 2-fold higher risk of developing breast and prostate cancer, respectively, as compared to the less-exposed population.