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Blue light filters don't work – controlling total luminance is a better bet

neuroai.science

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Re: Blue light filters don't work – controlling total luminance is a better bet

#141

Post by hn_throwaway_99 »

I found the basic premise of this blog post to be incredibly flawed. The author seems very sure of himself that blue light filters don't work, but making arguments related to cell types and emissions spectra and circadian rhythms is not the way to make a conclusive argument in a topic like this. Science is littered with recommendations about things that "plausibly" made sense, but that turned out to be flawed or just absolutely wrong when actually put to a real, scientific test. One example most people are familiar with: the recommendation against eating eggs in the 90s was based on the fact that eggs have a lot of cholesterol, and we knew high LDL levels in blood were associated with a greater risk of vascular and heart problems. So, "logically", it seemed that limiting dietary cholesterol would reduce heart disease. Except when scientists actually tested those recommendations, they turned out to be largely wrong - when you eat a lot of cholesterol, for most people their body's natural production of cholesterol goes down, so unless you're in the small subset of people who are particularly sensitive to dietary cholesterol, eating eggs is fine.

Making recommendations based solely on a theoretical mechanism of action is bad science. The only way to actually test this is with a study that looks at different types of light restriction and its effect on sleep. Obviously it's kind of impossible to do a blinded study for blue light filters, but you could get close by testing various permutations of light changes (e.g. total luminescence, eliminating only very specific wavelengths, etc.)

As another commenter said, it may be a placebo effect, but if it is, who cares? All I care about is that I get a better night sleep, and as someone (unusual among programmers I know) who really doesn't like dark mode, a screen reddener greatly helps me at bedtime.

Re: Blue light filters don't work – controlling total luminance is a better bet

#142

Post by nandomrumber »

zcw100 wrote: post #92

I replaced all the light switches in my house with smart dimmers and have the lights dim in the evening. It happens in steps so it's noticeable and it's like a clock ticking down. I don't know if there's anything scientific about it but it's pleasant, like the house is going to sleep so maybe I should too.

I like to use the yellow anti-insect lights for the external lighting around my house as they tend to attract way fewer flying insects and fewer spiders as a result.

I also like them in lamps inside for illumination during the evening, with the added benefit of not requiring more IoT devices.

Re: Blue light filters don't work – controlling total luminance is a better bet

#143

Post by lotu »

lisper wrote: post #35

Night shift seems to have a very strong causal effect on my sleep cycles. Up until about ten years ago I was a night owl, rarely falling asleep before midnight and rarely waking up before 8. Then I started getting serious about light hygiene and using night shift and now I'm a serious day person, rarely staying awake after 11 and rarely waking up after 7. But the real clincher is that when I travel I don't change the…

I remember when I found Flux (third party predecessor to night shift) sometime in 2013. It worked in a week, I'd been staying up until 3am for most of the year and a started going to bed at midnight.

Re: Blue light filters don't work – controlling total luminance is a better bet

#144

Post by daneel_w »

In summary blue light filters actually do work, through the indirect action of reducing overall light output, but the author has a larger axe to grind about the "technical details" (it's worth reading the article). The warmer color temperature reduces strain on my eyes, which I find both soothing and invaluable.

Re: Blue light filters don't work – controlling total luminance is a better bet

#145

Post by MBCook »

aethrum wrote: post #9

They absolutely help my eyes not be so strained. If its placebo, its a working placebo. >Are people actually using Night Shift? >Aggravatingly, yes. What is the authors problem lol? It feels a lot better on eyeballs to use warm light things. Why does he care?

Is the author arguing anything about eye strain? The word “strain“ doesn’t even appear on the page.

I think they’re purely talking about the idea that cutting back on blue light will help you sleep better. Nothing else.

Why would the author care? Honestly it does seem like one of those junk science things that popped up a couple years ago that all of a sudden was everywhere. I literally remember comments here on hacker news from people saying Apple was killing people because they were blocking F.lux and didn’t have night shift yet. Yes they were the most hyperbolic, but they were there.

I kind of like Night Shift too, for similar reasons. But I don’t think it ever did anything for my sleep. Nor did I ever expect it to.

Re: Blue light filters don't work – controlling total luminance is a better bet

#146

Post by MBCook »

daneel_w wrote: post #144

In summary blue light filters actually do work, through the indirect action of reducing overall light output, but the author has a larger axe to grind about the "technical details" (it's worth reading the article). The warmer color temperature reduces strain on my eyes, which I find both soothing and invaluable.

The author showed that Apple‘s implementation only cuts two colors by roughly 50%. And given we perceived light non-linearly aren’t they right that that really doesn’t make much of a difference?

If someone put up an article saying “Turning down your headphones 1% will help stop hearing loss!“ most people are going to ignore it. OK yeah technically it will, but not to any meaningful amount.

Re: Blue light filters don't work – controlling total luminance is a better bet

#147

Post by galangalalgol »

hn_throwaway_99 wrote: post #141

I found the basic premise of this blog post to be incredibly flawed. The author seems very sure of himself that blue light filters don't work, but making arguments related to cell types and emissions spectra and circadian rhythms is not the way to make a conclusive argument in a topic like this. Science is littered with recommendations about things that "plausibly" made sense, but that turned out to be flawed or just…

His argument seems to be that the night modes don't remove much blue. My initial assumption was that it was about physical filters. Yellow or amber 99%+ safety lenses are a thing and several of my coworkers wear them. Looking through them at those painfully bright blue leds makes them appear to be off. Yes everything looks strange, but they work. Likewise a different coworker manually removes all blue in the monitor settings themselves independent of the brightness setting. That also works. The author's assertion should be qualified amd narrowed a bit.

Re: Blue light filters don't work – controlling total luminance is a better bet

#148

Post by dinkelberg »

Groxx wrote: post #60
SoftTalker wrote: post #40

Earlier quoted context omitted.

So buy 5mg, and split the tablet in half.

that'd give you 2.5mg, which is still almost 10x more than what I linked. it's possible to split and separate them enough of course, but beyond "roughly half" it gets rather difficult. I've considered getting the liquid ones and a micro-dropper for smaller doses (if they'd even be small enough, many combinations are not), but 0.3mg pills are rather convenient and worth the small amount of money for me.

Melatonin pills seem to have extremely bad quality control:

"Melatonin content varied from an egregious −83% to +478% of labeled melatonin and 70% had melatonin concentration ≤ 10% of what was claimed. Worse yet, the content of melatonin between lots of the same product varied by as much as 465%.

[...]

The last disturbing finding was more than a quarter of melatonin products contained serotonin, some at potentially significant doses."

https://pmc.ncbi.nlm.nih.gov/articles/PMC5263069/

"In products that contained melatonin, the actual quantity of melatonin ranged from 74% to 347% of the labeled quantity. Twenty-two of 25 products (88%) were inaccurately labeled, and only 3 products (12%) contained a quantity of melatonin that was within ±10% of the declared quantity. [...] Serotonin was not detected in any product."

https://jamanetwork.com/journals/jama/fullarticle/2804077

"Half of the products tested met the label’s claim for melatonin, which means they fell between 76 and 126 percent of the claimed amount. Of the products tested, 20 had between 0 and 76 percent of the labeled content, and 35 had between 126 and 667 percent."

https://www.washingtonpost.com/wellness/2025/06/25/melatonin...

Re: Blue light filters don't work – controlling total luminance is a better bet

#149

Post by dragonwriter »

dinkelberg wrote: post #148
Groxx wrote: post #60

Earlier quoted context omitted.

that'd give you 2.5mg, which is still almost 10x more than what I linked. it's possible to split and separate them enough of course, but beyond "roughly half" it gets rather difficult. I've considered getting the liquid ones and a micro-dropper for smaller doses (if they'd even be small enough, many combinations are not), but 0.3mg pills are rather convenient and worth the small amount of money for me.

Melatonin pills seem to have extremely bad quality control: "Melatonin content varied from an egregious −83% to +478% of labeled melatonin and 70% had melatonin concentration ≤ 10% of what was claimed. Worse yet, the content of melatonin between lots of the same product varied by as much as 465%. [...] The last disturbing finding was more than a quarter of melatonin products contained serotonin, some at potentially s…

> Melatonin pills seem to have extremely bad quality control:

Melatonin is treated as a dietary supplement in the US rather than a drug, and this seems to be a widespread problem with supplements, given the incredibly lax regulatory regime.

Re: Blue light filters don't work – controlling total luminance is a better bet

#150

Post by dinkelberg »

dinkelberg wrote: post #148
Groxx wrote: post #60

Earlier quoted context omitted.

that'd give you 2.5mg, which is still almost 10x more than what I linked. it's possible to split and separate them enough of course, but beyond "roughly half" it gets rather difficult. I've considered getting the liquid ones and a micro-dropper for smaller doses (if they'd even be small enough, many combinations are not), but 0.3mg pills are rather convenient and worth the small amount of money for me.

Melatonin pills seem to have extremely bad quality control: "Melatonin content varied from an egregious −83% to +478% of labeled melatonin and 70% had melatonin concentration ≤ 10% of what was claimed. Worse yet, the content of melatonin between lots of the same product varied by as much as 465%. [...] The last disturbing finding was more than a quarter of melatonin products contained serotonin, some at potentially s…

One more relevant study, but on the health effects of long term melatonin use:

https://newsroom.heart.org/news/long-term-use-of-melatonin-s...

"The main analysis found:

* Among adults with insomnia, those whose electronic health records indicated long-term melatonin use (12 months or more) had about a 90% higher chance of incident heart failure over 5 years compared with matched non-users (4.6% vs. 2.7%, respectively). * There was a similar result (82% higher) when researchers analyzed people who had at least 2 melatonin prescriptions filled at least 90 days apart. (Melatonin is only available by prescription in the United Kingdom.)

A secondary analysis found:

* Participants taking melatonin were nearly 3.5 times as likely to be hospitalized for heart failure when compared to those not taking melatonin (19.0% vs. 6.6%, respectively). * Participants in the melatonin group were nearly twice as likely to die from any cause than those in the non-melatonin group (7.8% vs. 4.3%, respectively) over the 5-year period."

However they were not able to control for severity of the insomnia and used dosage, because that data weren't in the dataset.

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