It’s a bit of an oversimplification to state that all blue light is bad. In fact, the blue-turquoise range of frequencies help regulate your body’s production of melatonin, the hormone that governs your sleep-wake cycle. Sunlight, an essential ingredient in human health, contains all frequencies of visible light, including the blue range. One particular frequency range, however, can do more harm than good if you receive too much of it. This blue-violet range, which lies between 415 and 455 nanometers, is called high-energy visible (HEV) light. It’s believed that excessive, concentrated exposure to HEV light can be a factor in the development of macular degeneration. Macular degeneration is a permanent, progressive disease of the retina that destroys your central field of vision. 

HEV light also appears to play a role in the form of digital eye strain known as computer vision syndrome. Modern LED monitors, tablet screens, and smartphone displays don’t generate a lot of blue light compared to natural sunlight, but they deliver it directly to the eyes at point-blank range, promoting eye fatigue and irritation. The fact that younger corneas are still developing is of particular concern to parents whose kids use digital devices.