If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Consumer Products


Shedding light on filtering spectacles

by Arminda Downey-Mavromatis
November 8, 2020 | A version of this story appeared in Volume 98, Issue 43


Blue-light blues

Photo of a woman with glasses reading an iPad in bed at night.
Credit: Shutterstock
Never a dull moment: Blue light can disrupt sleep-signaling hormones.

We are spending record time on our devices, with activities like keeping in touch with friends and family on our phones and working 9–5 on our computers. We’ve heard that the blue light from these devices can affect sleep and cause eye discomfort. But this Newscriptster was curious—could blue light really be all that bad?

It turns out that the negative hype surrounding blue light is mostly unfounded, says Phillip Yuhas, an assistant professor of optometry at the Ohio State University.

“I would actually argue that our blue-light exposure as a species has probably gone down over the last hundred years or so,” Yuhas tells Newscripts. He says most of our blue-light exposure comes from the sun, not our devices, and because people spend a lot of time indoors, we aren’t getting the exposure we used to.

So how did blue light become a villain? Yuhas says that compared with other colors of light, blue light has a short wavelength and high energy. Eye cells called intrinsically photosensitive retinal ganglion cells relay signals to the suprachiasmatic nucleus, the body’s internal clock. They contain melanopsin, a pigment especially sensitive to blue light (J. Biophotonics 2019, DOI: 10.1002/jbio.201900102).

Thinking blue-light-filtering glasses might reduce eye strain, this Newscriptster looked into buying them to make screen time less painful. But these glasses may not work the way that companies claim they do.

Previous work has shown that blue light can suppress the body’s ability to make melatonin, a hormone that the brain produces in response to darkness and that signals to us that it’s time to sleep. Researchers compared blue-light-filtering glasses with smartphones in night-shift mode, which warms displays during evening hours, to see which suppresses calculated melatonin production the least. The study found that smartphones in night-shift mode would be more effective at reducing melatonin suppression than wearing blue-light-filtering glasses. Moreover, they found that the commonly sold, antireflective coated, blue-light-filtering glasses they tested filtered out only around 18% of blue light (Optom. Vision Sci. 2020, DOI: 10.1097/OPX.0000000000001485). A 2017 review in Ophthalmic and Physiological Optics also concluded that the use of blue-light-filtering glasses does not assist with sleep, eye strain, or overall eye health (DOI: 10.1111/opo.12406). At least one UK company selling blue-light-filtering glasses has faced fines from the General Optical Council, a regulatory body for UK opticians and optometrists, for misrepresenting the benefits of its product.

Blue light may not be the bad guy, but that doesn’t mean other colors of light are totally harmless, at least when it comes to sleep.

“All lights, any color—yellow, orange, red, green, whatever—can affect your sleep if it’s bright enough,” Yuhas says. Yuhas says that instead of hiding from blue light, people can use dimmer screens to improve sleep. And besides using night-shift mode to prevent phone-related insomnia, he has other suggestions for those tired of staring at screens. He recommends taking breaks from screens in the form of the 20-20-20 rule: taking a 20 s reprieve from screens every 20 min, looking 20 ft away (or 6 m away for fans of the metric system). This reduces eye strain and provides an opportunity to blink. He also suggests using high-quality lubricating eye drops before long stretches of screen time.

Beyond screen color, there are other things we can do to keep our eyes happy and healthy. As winter approaches, humidity decreases, which can cause eye dryness, says Sunir Garg, a spokesperson for the American Academy of Ophthalmology and professor of ophthalmology at Wills Eye Hospital. “Getting a humidifier for your work space, and perhaps another one in the bedroom or family room, can also be quite helpful,” he tells Newscripts. We’ll be adding this to our holiday shopping list. And perhaps turning to a good book under a soft lamp instead of sending late-night texts.

Please send comments and suggestions to


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.