White light is produced by the sun. This white light is composed of different colored lights that have different energy and wavelengths. Red light consists of longer wavelengths and less energy. While blue light consists of a shorter wavelength and more energy. The blue light end of the spectrum is referred to as the high energy visible light. One-third of all visible light is considered blue light. Blue light is produced by many different sources with both beneficial and harmful qualities.
The largest source of blue light is the sun. Smaller sources of blue light include fluorescent lights, compact fluorescent light bulbs, LED lights, LED flat screen televisions, computer monitors, smartphones and tablet screens. These smaller sources may produce less blue light, however today’s generation has dramatically increased screen time with these smaller devices.
Studies have shown that almost 50% of working adults require prolonged screen time for their jobs. Children today are also increasing screen time with more video games and homework on computers rather than on paper.
Blue light exposure in the daytime is good for regulating circadian rhythm. Circadian rhythm is our natural waking and sleep cycle. When exposed in the early part of the day, blue light can help boost alertness, increase mood and memory. Too much blue light exposure at night can disturb the cycle and cause increased daytime fatigue.
There is new research regarding Blue light and its effects on the eye. The cornea and lens do well at blocking UV light but not so well at blocking blue light. Researchers are trying to determine if long term blue light exposure to the retina can potentially cause changes resembling macular degeneration.
There are other studies researching the flicker effect of Blue light that causes decreased contrast sensitivity. This flickering is believed to contribute to digital eye strain.
Blue light is everywhere and has played a role in our overall health and eye health since infancy. The best advice at this point is to decrease screen time, especially right before bed. Recommend your children play outside more for a healthy dose of blue wavelengths versus playing video games. However, it is important to be sure you and your children wear sunscreen when outdoors as the other end of the light spectrum causes sunburn.
Author: Theodore Hallberg, OD