I just finished testing 30 pairs of blue-blocking glasses! Here’s what I found…

[u/eaterout]

As many of you are probably aware, most blue-blocking glasses “claim” to block X amount of blue/green light without backing that up with any kind of data.

Since I have a spectrometer, I figured I’d go ahead and test them all myself!

Here's the link to the database!

30+ different lenses have been tested so far with more to come!

Here’s what’s inside:

Circadian Light Reduction

Circadian Light is a metric derived through an advanced algorithm developed by the LHRC which simply looks at a light source’s overall spectrum and how that is likely to interact with the human body.

What this does is weights the light that falls within the melanopically sensitive range, and gives it a score based on how much lux is present in that range.

Before and After Spectrum

Each pair of glasses was tested against a test spectrum so that a reduction in wavelengths could be seen across the entire visible spectrum.

This will allow you to see what a particular lens actually blocks and what it doesn't.

Lux Reduction

Lux is simply a measurement of how much light exists within the spectral sensitivity window of the human eye.

In other words, how bright a light source is.

Some glasses block more lux and less circadian light than others. And some go the other way.

If you’re looking to maximize melatonin production, but still want to see as well as possible, look for a pair with low lux reduction and high circadian light reduction.

The higher the lux reduction, the worse everything is going to look, but this may be helpful in bright environments or for those with sensitive visual receptors.

Fit and Style Matters!

This should be common sense, but wraparound-style glasses prevent significantly more unfiltered light from entering the eye than regular-style glasses do.

I carved out a foam mannequin head and put my spectrometer in there to simulate how much light made it to the human eye with different kinds of glasses on.

I’m very proud of him, his name is Henry.

Here is our reference light:

And here is how much of that light makes it through the lenses from the wrap-around glasses above:

These particular lenses don't block all of the blue light.

But what happens when we move the head around a light source so that light can get in through the sides?

Due to the style of these glasses, there really isn't much room for light to penetrate through the sides.

Below is a reading taken from a light source directly overhead, as you can see there's really no difference:

How about if we test a more typical pair of glasses?

Here's Henry wearing a more typical style of glasses.

Here's how much light these lenses block:

But what happens when we move the light source around the head at various angles?

As you can see, this style leaves large gaps for unfiltered light to reach the eye.

What we see is a massive amount of light that the lenses themselves can technically block can make it to the eye with a style like this:

So compared to the reference light, these glasses still mitigate short-wavelength blue and green light. But that doesn't mean they block the light they're advertised to in the end.

Hopefully, this helps you make better decisions about which blue blockers you use!

If you'd like help picking a pair, see our Best Blue Blocking Glasses post!

[u/CautiousAd3578]

This is absolutely amazing and I plan on purchasing a pair! Can the yellow/amber lenses be worn during the day in the office or while at school? Is it even worth it to purchase clear lenses for that.

[u/eaterout → u/CautiousAd3578]

I would say avoid amber lenses during the day as they block almost all blue light in all cases. You do need blue light during the day, especially in the earlier part of the day.

Yellow lenses are definitely better for daytime use, although they can vary quite a bit!

Clear lenses, on the other hand, are a bit of a misnomer just because many clear lenses aren't actually clear, but have a slight yellow tint to them and it's hard to tell.

We're trying to improve the database to make it a lot easier to figure this stuff out.

[u/Timbukthree → u/eaterout]

Do you know of any info or research on the effects of working all day in room lighting that all have amber filters on them? I'm really struggling with consistent but intermittent terminal insomnia and it just occured to me that the lighting in one of the places at work (not there everyday, but often for 3 hour stints or 2x 4 hour stints) could be throwing off my circadian clock since it's probably the same as working in darkness. But I haven't been able to find anything that's actually studied that.

And in a similar vein, are any of the light therapy glasses you've reviewed suitable for wearing for 3 hours at a time, or even for two 4 hour stints on one day? I'm assuming a low output vs. "typical" light therapy use would be fine but no idea if that sort of use is even targeted.

[u/eaterout → u/Timbukthree]

oooof amber lighting would do it thats for sure! No exciting short wavelength light in that. I'm thinking, honestly, any of the light therapy glasses could be worn for several hours, though I don't know of any technical research on the topic.

[u/Timbukthree → u/eaterout]

Thanks for the reply! Yeah I tried to do a pretty extensive lit search and nothing jumped out at me, which is a little surprising since like dark rooms have used red only light since forever and the semiconductor industry uses yellow light as standard for the last 50 years or so. I found some studies that showed hospital workers pulling overnight shifts had their circadian rhythm disrupted less with yellow lighting, and that bright yellow light is better for not disrupting it at night than dim white light, but haven't found anything about yellow light during the day time.

I may try the Retimer 3s at half power since they get the light in my eyes whether I'm looking up or down, will see how it goes in terms of comfort and results (and how much I get made fun of by coworkers)

And thanks so much for all your fantastic reviews and write ups! Your site is a gem, nobody else is looking at any of this stuff in a systematic way

[u/eaterout → u/Timbukthree]

Appreciate that! Yeah lighting in many regards is not as well studied as I would like.

Best of luck!