Sunlight constitutes of red, orange, yellow, blue, indigo, and violet. When these colours combine, they form the white light that we see. Each of these colours has a different wavelength and energy level, with blue having a shorter wavelength and more energy and red having a longer wavelength and less energy. Light that appears white may contain more blue wavelengths. Sunlight is the most abundant source of blue light. Fluorescent lighting, LED lighting, flat-screen LED televisions, computer monitors, smart phones, and tablet screens are among the others.
Almost all visible blue light is absorbed by the cornea and lens before reaching the retina. This light could impair vision and prematurely age the eyes. According to preliminary research, excessive blue light exposure may cause (1) digital eyestrain (2) retinal damage.
At night, blue light, which appears to be beneficial during the day, appears to be the most disruptive. Blue light is beneficial during the day because it can improve attention, reaction times, and mood; however, with the proliferation of electronics with screens and energy efficient lighting, humans are constantly exposed to blue wavelength, particularly after sundown.
According to research, exposure to blue wavelengths after sundown affects the body's circadian rhythm, increase risk of diabetes, heart disease, and obesity.
A Harvard study found a possible link between light after sundown, the body's circadian rhythm, diabetes, and obesity. The researchers put ten people on a schedule that gradually shifted their circadian rhythm timing. Their blood sugar levels increase, putting them at risk of diabetes, and their leptin levels increase as well (a hormone that promotes feeling full after a meal, went down).
Another blue light study compared the effects of 6.5 hours of blue light exposure to exposure to green light of comparable brightness. Blue light suppressed melatonin about twice as much as green light during the same exposure period, which shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).
In conclusion, blue light after sundown can affect health in a variety of ways. While we need this to progress in this modern society, we can also make minor adjustments to make things work without jeopardizing health.