Do Blue Blockers Work?
Google blue-blocking glasses, and you’ll immediately face a wide array of choices. From cheap, orange frames that belong in a science lab to pricer options that are indistinguishable from normal clear lenses, it’s not hard to feel overwhelmed.
Blue-blocking glasses are marketed for three primary use cases:
- Preventing permanent eye damage
- Reducing eyestrain from computer use
- Mitigating sleep interruption
In this article, I’ll examine whether these claims hold up. I’ll look at three types of blue-blocking glasses and help you decide which technologies are worth your time.
Can blue light cause permanent eye damage?
For most people, the sun is the most powerful blue light source by far.
Almost all indoor light, including light produced by computers and phones, is only a small fraction of the brightness of outdoor light. Serious eye diseases, including macular degeneration and cataracts, are unlikely to result from exposure to indoor light sources.
There is a standard eye safety measurement known as blue light hazard. According to f.lux creator Michael Herf, “computer screens have <5% the hazard-weighted irradiance of a blue sky.” In other words, computer screens are unlikely to present a blue light hazard risk.
A study published last year by researchers at The University of Toledo claimed that blue light caused permanent, irreversible retinal damage. But further investigation revealed the experimenters likely used an extremely intense light source, perhaps even a laser. None of us are exposed to blue light levels anywhere near as intense.
Is it wise to wear quality sunglasses on a sunny day? Absolutely. But there is no reason to be alarmed by exaggerated claims of computer screens causing permanent eye damage.
Is reducing blue light effective for eyestrain?
Based on our current knowledge, blue light produced by computer displays does not cause permanent eye damage. But can it still lead to eyestrain?
Experts believe these other factors are more likely to play a role in digital eyestrain:
- The brightness and contrast of the display
- The refresh rate (flicker frequency) of the screen
- Decreased blinking from staring at the screen
- Glare reflected from displays without a matte coating
While a number of popular brands of computer glasses offer a low level of blue light reduction, this is not the primary reason they can claim to reduce eyestrain. Instead, computer glasses often have a slight amount of magnification coupled with a narrow pupillary distance, making it easier for your eyes to focus on objects a short distance away.
So are computer glasses useless? Probably not. But before investing in a pair, try to adjust your display settings and follow the 20–20–20 rule.
Can blue blockers improve sleep?
Here’s where blue blocking technologies may actually be effective. Numerous studies have shown that too much blue and green light in the hours leading up to bedtime can have an adverse effect on sleep.
Although you should expose yourself to significant quantities of blue and green light during the day, at night, you should aim to reduce blue and green.
The graph below shows a typical “soft white” LED light source. The gray area from about 390–600 nanometers is the sensitivity of melanopsin (which tells the body whether or not it is daytime):
The next graph shows the intensity of that same LED source compared to the brightness of moonlight:
Even though the LED light is far dimmer than the sun, it is still hundreds of times as bright as moonlight. Almost all indoor light sources produce enough blue and green light to disturb sleep.
The right pair of blue blockers can mitigate sleep interruption from blue and green light. In the next section, I’ll cover the major types of blue-blocking glasses.
Three types of blue-blocking glasses.
There are 3 major types of blue-blocking glasses, based on the color of the lens:
- Orange lenses (e.g. Uvex SCT* and Swannies)
- Yellow lenses (e.g. Gunnar)
- Clear lenses (e.g. Felix Gray and BluTech)
We will use spectra to demonstrate the amount of light each type of glasses allows through. The following spectrum shows no intervention (i.e. not wearing any glasses) under a normalized light source. The region we want to pay attention to is the curve from about 390 to 600 nanometers:
In general, orange lenses are most effective in eliminating blue and green, especially the ones that wrap around.
The following spectrum shows all the light that UVEX SCT* lenses allow through. Notice that barely any green light is transmitted, and blue is entirely absent. Other orange lenses will show a similar, but not identical, spectrum:
The downside of this design is that everything will look extremely orange. And these frames can be pretty socially unacceptable. For most people, orange-lens blue blockers are overkill.
Yellow lenses are typically marketed for computer use, but increasingly also for sleep. They are the closest to f.lux on the default settings in terms of color and performance.
The following spectrum shows the light transmittance of Gamma Ray* brand computer glasses. While some blue and green are allowed through, there is still a significant reduction:
Yellow lenses are not as effective as orange if your goal is total blue/green reduction, but for most people, these represent a great balance of practicality and performance.
Side note: Even getting half the amount of blue and green is a major improvement. Our Bedtime Bulb still produces some blue and green (4% blue and 17% green), because we found that pure orange/red/amber lighting was impractical for most people. Many would switch back to their old lighting, totally defeating the purpose of the “no blue” lighting. Yellow lenses are similarly practical.
Finally, we will take a look at clear blue-blocking lenses, which are also marketed as computer glasses. These lenses look like regular glasses, showing only a very slight yellow tint.
The following spectrum comes from a pair of BluTech blue-blocking glasses:
Clear blue-blockers do reduce blue and green, but only by a very small amount. I wouldn’t waste your time with clear-lensed blue blockers for sleep.
Don't take my word for it
You can see for yourself the effectiveness of different brands/lens types with f.luxometer. Here is the effectiveness of the three lens types on an iPad screen:
• Orange (Uvex SCT)
• Yellow (Gamma Ray Computer)
• Clear (BluTech)
To see other filter brands, you can use the Filter dropdown. Unfortunately, that database is incomplete, but I think you can extrapolate to other brands and models based on the color of the lens.
- Indoor light sources, including phones and computers, are unlikely to cause eye damage.
- Blue light filters are ineffective for preventing digital eyestrain.
- The right type of blue-blocking glasses can mitigate sleep interruption from blue and green light.
- For sleep: orange lenses are the most effective, but impractical. Clear lenses do almost nothing. Yellow lenses present the best balance.
- Low-blue lighting (such as Bedtime Bulb) and blue light filtering software (such as f.lux) can have the same effect as blue-blocking glasses.
About the author
Continuing a lifelong obsession with light, Greg Yeutter founded SimpleBulb Inc. to make lighting simple and healthy. Bedtime Bulb is the beginning of the #healthylight revolution.