All of the light the human eye can see falls somewhere on the visible light spectrum. Each color of light has a different wavelength, with blue light being on the low end of the spectrum, between 380 and 500 nanometers.
Light with shorter wavelengths, like blue light, has higher energy. This is why we refer to blue light as High-Energy Visible light (HEV).
While the largest producer of natural blue light is the sun, devices like laptops, smartphones, tablets, and even LED lighting all emit blue light. Many people spend countless hours a day staring at digital screens for both work and entertainment. For this reason, eye doctors are concerned that overexposure to blue light may be causing symptoms of eye strain and even sleep disruptions.