Blue Flashing Light

Have we let the LED indicator light go too far? These lights are everywhere, and they make it hard to sleep. Here’s a case for some less-annoying indicators.

By Ernie Smith

Today in Tedium: There’s a light on the front of my TV set—a 55-inch TCL Roku TV set, of the kind that people who just want an inexpensive big TV buy—that I find annoying. It seems like a light that exists basically for show. A lot of our electronics have these annoying lights, especially set-top boxes that don’t really do much more than sit there most of the time. Yes, indicator lights are useful—a quick way of knowing whether your laptop is charging or you’ve gotten a notification of some kind—but they can be maddening when they’re too in-your-face. Recently, a follower of mine on Twitter, Michael Krakovskiy, posed what I thought was an amazing suggestion regarding these flashing lights, along with loud buzzing noises and internet access: A company should actively develop products without them, and specialize in it. (Somewhat in jest; he did suggest a router without internet access.) How did we get here, to a place where indicator lights became a constant annoyance? And how do we get out? Today’s Tedium puts some harsh (but focused) light on the situation. — Ernie @ Tedium


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The year that Nick Holonyak, a researcher working for General Electric, first invented the light-emitting diode, an electric component that could display visible light—specifically, the color red. (LEDs that could produce infrared light were in existence before then, just in time for the invention of the remote control.) Holonyak noted in a GE news release that his invention was driven by a desire to build a laser. “If they can make a laser, I can make a better laser than any of them because I’ve made this alloy that is in the red—visible. And I’m going to be able to see what’s going on. And they’re stuck in the infrared.” Holonyak’s invention relied on the use of gallium arsenide phosphide, a semiconductor material. (A related material, gallium arsenide, has at times been pitched as replacement for silicon in computers.)

LED lights

(Teigan Rodger/Unsplash)

Why these tiny little lights feel so harsh to your eyes

A little over four years ago, the American Medical Association felt compelled to publicly raise concerns with a growing trend on many highways—the replacement of older lighting systems with new ones that used LED lighting.

The reason? The new lights were often too harsh.

“High-intensity LED lighting designs emit a large amount of blue light that appears white to the naked eye and create worse nighttime glare than conventional lighting,” the association warned. “Discomfort and disability from intense, blue-rich LED lighting can decrease visual acuity and safety, resulting in concerns and creating a road hazard.”

But why blue light in particular? What about it makes it so awful on your eyes? And does the problem scale down?

This is a question, of course, that scientists have been researching for decades … without realizing it. In 1958, researchers J. Woodland Hastings (an expert in photobiology) and Beatrice M. Sweeney (a plant physiologist) published a paper, “Characteristics of the diurnal rhythm of luminescence in Gonyaulax polyedra,” that analyzed the impact of different colors of light on the Gonyaulax polyedra, a kind of dinoflagellate (a single-celled organism) with the ability to emit light.

This early paper, which actually predates the visible LED by a few years, noted that the organism reacted differently to varying colors of light, with its strongest reaction to the color blue, and perhaps a lesser one to the color red. It affected their circadian rhythm, or their sleep-wake cycle. It was an interesting piece of research, but it didn’t gain major significance in the broader scientific community until decades later, after both scientists had passed.

In a 2010 article for the academic journal Environmental Health Perspectives, author David C. Holzman noted the reason for that—it turns out that what affects single-cell organisms also affects humans:

Hastings and Sweeney’s paper, published in the December 1958 Biological Bulletin, gathered dust for decades. No one thought these findings might hold any relevance for humans, whose circadian rhythms were then widely believed to be relatively insensitive to light.

But scientific discoveries in the past two decades have changed all that. Not only does light reset the human circadian rhythm, but the same blue light that has the strongest impact on dinoflagellates has equal power to reset our own clocks—although most visible wavelengths can reset the clock, the blues do the job with the greatest efficiency.

And blue light, a key part of what makes light visible and vibrant, is everywhere, especially in screens and other artificial light sources. It’s widely considered the reason why you might struggle to go to bed if you’ve been looking at your laptop or smartphone beforehand.

This, of course, is not new information and if you’ve read any pop-science content on the internet in the past decade, you’ve most assuredly heard about how blue light is bad for you and harms your sleep cycle.

Blue Glowing LED


But this explanation gets to the heart of the problem we face with individual LEDs that flash in our faces at all hours of the day. Blue LEDs, which again tend to be the brightest, were actually the hardest to generate. The complication was such that, when three Japanese researchers—Shuji Nakamura, Isamu Akasaki, and Hiroshi Amano—did figure it out, it eventually earned them a Nobel Prize for physics.

(Side note: Nick Holonyak Jr. was notably salty about not getting a Nobel Prize when the inventors of the blue LED did.)

The invention of the blue LED is at the center of the what gives us white LED light, which has revolutionized the lighting industry—but which some consider harsh, which means it can have the same problems as blue light. (Hence the AMA messaging against using it for street lights.)

But even before then, people were noticing the harshness of blue LEDs in electronics such as routers and computer monitors. As Ian Johnson wrote for The Globe and Mail in 2004, before the concerns about blue light really went mainstream:

Blue LEDs have a piercing clarity that draws the eye immediately, and which can mesmerize. They shimmer, they twinkle, and they can be incredibly intense for such tiny points of light—they’re really quite beautiful.

The problem is they’re suddenly everywhere.

They adorn my monitor, handheld scanner, webcam, a USB hub, a Bluetooth access point, a WiFi adapter, a desktop volume control for my speakers, an external hard drive, a video editing peripheral (that one actually pulses), and the docking cradle for a rechargeable mouse. There are six more on the front of my new computer.

And they do pierce. My wireless router, for example, uses blue lights to let me know about network traffic patterns, and they are harsh to the point of distraction, despite being behind a thick layer of plastic. Yet they’re somehow less distracting than the white light on the nearby TV set, which is produced by combining blue LEDs with other colors, and significantly larger than it needs to be. (On the plus side, I learned recently that this annoying light, which is not particularly necessary, can be turned off. I just turned it off. Thank the Lord.)

But even before everything went blue, it wasn’t like red LEDs—the basis of many alarm clocks and old Hayes modems—or green LEDs were any better. They tend to distract in large part because of a lack of subtlety. They make their appearance known, even as their glow is inherently focused and tightly wound.

At 2 a.m. in the morning, a small LED indicator can be enough to thrust you from sleep mode, to pull you out of a normal circadian rhythm. And it can be quite distracting.


The year that software developers Michael and Lorna Herf came up with the application F.lux, which removes blue light from screens in an effort to better match circadian rhythms. The application, which started as a Mac app but has since expanded to every major software platform, effectively yellows out the screen, making it carry the tone of a candle at its lowest setting. (It also allows you to use a “dark room” mode that essentially makes your computer look like it’s using a black-and-yellow CRT from 1980. It’s kind of neat.) Apple, of course, Sherlocked it a few years ago, but as Lifehacker notes, F.lux remains far more customizable.

Alarm Clock Light

Green isn’t as bad as blue or red, but it still grabs you. (Michael Galpert/Flickr)

Can we make bright LEDs less annoying?

Now, indicator lights obviously predate the LED. Doing a little digging through history, you’ll find examples of railroads and ships using indicator lights or warning lights during the 19th century. The United States Naval Signal Code, published in 1867, discusses a wide array of “signal lights” to be used during the evening hours.

A Honolulu opera house also used then-new incandescent indicator lights way back in 1897, making them a notable early user of the form.

Indicator Lights

A diagram explaining how to install indicator lights into a 1920s-era vehicle. (Google Books)

A 1927 Popular Science article, meanwhile, makes the case for installing your own indicator lights inside a vehicle.

Of course, cars had indicator lights long before they relied on light-emitting diodes, and while LEDs definitely have their purpose—especially, for example, in places where you need to see lights in the dark, such as a car dashboard or a backlit computer keyboard—one can argue that we might be at a point of overuse when it comes to indicator LEDs.

Let me offer an example. Last year I got a pair of bookshelf speakers made by a company named Edifier. I love these speakers because they allow me to crank up Jeff Rosenstock’s Worry without worry. They’re loud, and they sound good. A secondary reason I got them was because they support Bluetooth, which occasionally comes in handy during times I want to play music from my phone, which doesn’t have a headphone jack.

But there’s an annoyance in doing so. Setting the speaker into Bluetooth mode means that the speakers, which are otherwise unlighted, suddenly have a bright blue light kicking out the side. I don’t need that light. I can figure out if the speaker is connected another way. It would arguably be smarter for the speaker to have some other way of making it clear the mode is set, possibly through a switch or something similar (though that would complicate its remote control capabilities, so maybe not).

To follow through the point, I wonder if there are use cases where LED lights are currently in use where an alternative technology would be just as effective without the distractive downsides. For example, in the case of routers, electronic ink, or e-ink, would be a more than suitable replacement for the array of lights that are essentially a holdover from the days of dial-up modems.

There are even some budding examples of color e-ink that have yet to take off essentially because they have the opposite problem to LEDs: They’re dull compared to your laptop monitor, with slow response time in comparison. It looks like color e-ink may only finally hit the mainstream market next year after years of work perfecting the technology.

Even so, they’d be perfect for a use case where often, users just want to have a notification that something is working.

Likewise, there is likely room for more to be done with haptic feedback outside of phones. A sign of vibration may be more effective with some kinds of electronics.

But for reasons related to ubiquity, cost (you can literally buy a 100-pack of blue LEDs for less than $7 on Amazon), and perhaps a lack of creativity, we got a hold of these LED lights and never really considered that there might be better product design solutions in some cases than having an indicator light in your face.

Admittedly, LED lights may in fact still make sense in some cases if they’re designed in a way that minimizes their luminance. Say, for example, the light shows up in more of a halo at the bottom, hiding the more intense element of the light from your retinas. By softening the effect it could potentially make it less problematic.

After all, if you’re using a TV set or a monitor, it’s generally obvious when it’s on and when it’s not.

Of course, there are lots of LED lights already lingering throughout your house that likely need to create a little less retinal impact.

Dim It Light Example

An example of what Dim It sheets apparently are able to do. (via the Dim It website)

And there are products that actually do this. One of the best known companies, a firm named Dim It, sells sheets that essentially cover up particularly bright LEDs to help tamp down some of their more disruptive effects. The company’s website discusses the technology as something of a miracle material:

Each package of Dim It includes two light dimming sheets. These sheets can be easily cut and trimmed to be any shape you need to fit over your devices LED lights. Instantly, the excessive brightness is reduced to a more comfortable level. Plus, Dim It’s light dimming sheets can be layered to further increase the dimming effect as needed. An added benefit of using Dim It is that it adheres to surfaces via static cling. Thus, there’s no messy adhesive and Dim It can be easily removed, re-positioned, and reused as many times as needed!

Feeling emboldened by my discovery that, yes, I can turn off the annoying LED on the bottom of my Roku TV’s screen, I might just look into this as a potential solution to tamp down some of the more aggressive blue lights in my life—the one on my monitor, the one on the power button of my Xeon, and those bright blue lights on my router. There is no reason these lights need to be as aggressively bright as they are, other than, y’know, science.

It’s nice that a product like this exists. Then again, there’s always masking tape.


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Ernie Smith

Your time was just wasted by Ernie Smith

Ernie Smith is the editor of Tedium, and an active internet snarker. Between his many internet side projects, he finds time to hang out with his wife Cat, who's funnier than he is.

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