The wavelength of visible light is between 400 nanometers and 700 nanometers, and the visible light between 400 nanometers and 500 nanometers appears blue to the human eye, and this band is blue light. Among the blue light, the blue light of 415-455 nanometers has a short wavelength and high energy, which is the most harmful to the eyes and is called harmful blue light.

Due to the extremely high energy of blue light radiation, it can directly penetrate the lens and irradiate the retina, thus causing the atrophy or even death of retinal pigment epithelial cells. Not only is this damage irreversible, but in the long term it can cause clouding of the lens, leading to macular degeneration and cataracts.

Blue light radiation also inhibits the secretion of melatonin, a hormone that is produced in the dark. Its function is to lower our blood pressure, glucose, and body temperature at night for a comfortable sleep. The radiation of blue light will reduce the secretion of melatonin by 22%, thus affecting the quality of sleep. It can be seen that blue light not only hurts the eyes, but also affects the endocrine, and the harm should not be underestimated.