Blue light is everywhere. There are many sources of blue light, the most powerful being the sun. The sun contains all the colors of the spectrum, red, green, yellow, orange, blue and every color in between depending on the wavelength. All those colors combine to make “white light”.
Colors that are just beyond the red end of the spectrum are invisible and are called infrared. The colors just beyond the blue end of the spectrum are invisible and are called ultraviolet (UV). The ultraviolet colors contain more energy than those on the red end.
The ultraviolet rays are beneficial in moderation because they help the body produce vitamin D. Too much exposure, however, can cause sunburn and possible adverse ocular health concerns. This high energy blue light is also why the sky looks blue! This blue light scatters much more as it passes through the atmospheric moisture causing the sky to look blue on a clear day.
This blue light scatter, however pretty, can also lead to digital eye strain if a lot of time is spent in front of a screen. This highly scattered light causes visual noise in which the eye has trouble focusing on. As the eye continually tries to focus on the blue light being emitted from the screen, fatigue can set in over time.
It's important to note that we can’t block blue light completely from our lives with sunglasses or other filters because it would be unhealthy. We need blue light to keep our sleep/wake cycles on track and it helps with fending off depression.
Long story short, blue light is necessary but it is important to be mindful of overexposure.