How Blue Light Affects Our Health

Depending on the time of day, blue light can be harmful or beneficial. Learn why we should balance the blue light in our lives, and how to do it.

| May/ June 2018

  • Whether by straining our eyes or disrupting our sleep schedules, our constant exposure to blue light is harming our health.
    Photo by Adobe Stock/Halfpoint
  • The sun is the largest source of our exposure to blue light, and during the day this light is natural and beneficial.
    Photo by Adobe Stock/nagornyisergiy
  • "Blue light" is the range of visible light on the electromagnetic spectrum from 380 to 500 nanometers.
    Photo by Getty Images/solar22

If you’ve shopped for eyeglasses or browsed digital apps lately, you may have noticed products claiming to reduce your exposure to blue light. What’s up with blue light, and why would you want to cut back on it?

You probably don’t think about light as having much of a color, but if you’ve looked at the nighttime glow from digital devices, including smartphones, laptops, and flat-screen TVs, you may have noticed a blue tinge. That’s because they’re illuminated with light-emitting diodes (LEDs), which are especially rich in “blue light” — visible light with a wavelength on the electromagnetic spectrum that ranges from 380 to 500 nanometers. Common energy-efficient LED lightbulbs and compact fluorescent lamps also emit a lot of blue light, unlike older incandescent bulbs.

The biggest source of blue light is the sun. But sunlight isn’t available 24/7, whereas the artificial blue light from digital devices and lightbulbs is. That’s where the problem lies. Whether straining our vulnerable eyes or disrupting our natural sleep schedules, our constant exposure to blue light is harming our daily well-being. Disrupted sleep can lead to decreased brain function. And the underlying cause of this disrupted sleep, a decline in the body’s production of melatonin, may increase the likelihood of certain cancers. Luckily, we can do something about these risks.

Light and Eye Health

Most obviously, staring at digital screens for several hours a day may cause eye strain, which can result in blurry vision, dry eyes, and headaches. Beyond that, it’s unclear whether modern-day exposures to blue light from digital devices pose a special risk to our eyes.



“Although blue light isn’t nearly as harmful to the eyes as ultraviolet (UV) light, it still has some of the same properties, so some scientists are concerned it may contribute to eye damage over time,” says Geoffrey Goodfellow, OD, an associate professor at the Illinois College of Optometry in Chicago. There’s no direct proof of this damage in the general population, but some research suggests that people with low blood levels of certain antioxidants may be more vulnerable to macular degeneration related to blue light exposure.

Many optometrist offices sell glasses with special lenses to help filter out blue light from digital devices, and numerous non-prescription options are available online. However, Goodfellow cautions that we don’t want to screen out all blue light during the daytime, such as by wearing 100-percent blue-blocking glasses. Blue light during the day helps keep our internal clock in rhythm and may help boost alertness and mood, as well as support memory and brain function. Plus, filtering out all blue light can distort colors. Due to this, the optical company Essilor and the Paris Vision Institute developed glasses with a feature that blocks about 20 percent of blue light — primarily deflecting the rays at the lower end of the blue light spectrum most likely to harm our eyes while transmitting the beneficial ones.






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