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

https://www.neuroai.science/p/blue-light-filters-dont-work

by pminimax • 5 months ago

234 243 5 months ago

neuroai.science

snet02• 5 months ago

But have you considered that it feels better?

stronglikedan• 5 months ago

so do placebos

kurthr• 5 months ago

I agree for sleep. I prefer them because they focus better for me.

Blue creates a halo around letters that is distracting with my declining vision.

Also, Blue fluorescent OLED are ~50% less efficient than R/G phosphorescent OLED so you can reduce screen power consumption of a full white page by almost 30% using such a filter. That in turn might be 30% of active device power consumption (for a total of almost 10% in battery life during active operation). Ignoring that they also tend to burn out more quickly, since tandem blue has become fairly mainstream.

Many more reasons for these "filters", if you don't mind the white balance shift and reduced color gamut.

snet02• 5 months ago

So what? If I could take a sugar pill that guaranteed I feel comfier looking at my screen, nobody can tell me it "doesn't work". I'm not trying to optimise my life, I'm trying to have my eyes feel better.

tshaddox• 5 months ago

Not really. Most of the cultural notion about the remarkable effects of placebos came from flawed studies in the 1950s. As far as I can tell, the modern consensus is that there's no clinically significant placebo effect except for conditions that can only be measured by a subject self-reporting their own perception (like pain and fatigue).

allthetime• 5 months ago

and? placebo is often effective.

debo_5• 5 months ago

Everybody wants better sleep

Bro, as someone who had brutal insomnia for a couple of years and now sleeps "normally" for whatever that means, I can tell you that I don't think about my sleep quality at all. I'm happy to be sleeping.

If you too sleep "ok" for whatever that means, maybe stop worrying about optimizing it and go do something else less insane.

loloquwowndueo• 5 months ago

What did you do to tackle your insomnia?

smt88• 5 months ago

Primary, idiopathic insomnia doesn't really exist. It's almost always anxiety, although a few other mental and physical conditions can also cause it. But more likely anxiety.

m30472• 5 months ago

Disturbed sleep / inability to settle / anxiety can have physical causes although these are poorly recognized / diagnosed by regular allopathic medicine where I live.

Anecdata: 1) A good friend whose anxiety was largely alleviated (and sleep improved) by recognizing and treating their iron deficiency. 2) I have to (can't take the Western drug which was prescribed any more, and the Western doctors can't seem to bang the rocks together) take herbs for my hypertension but as opposed to the side effects I was experiencing from the drug I joke that all of the "side effects" from the herbs are good, they're targeting imbalances which were not recognized / treated previously and lo and behold I settle and sleep better... which helps reduce the blood pressure.

debo_5• 5 months ago

I spoke about it in this video: https://www.youtube.com/watch?v=QnNPRqLVtaM

nine_k• 5 months ago

Waking up tired and with the brain full of fog is nearly as fun as not sleeping and ending up tired, with the brain full of fog. Truth be told, most cases of "poor sleep quality" are not as brutal though.

kqr• 5 months ago

The charitable reading of "better sleep" is "sleep habits that allow for a healthy amount of sleep". A lot of people have habits that give them insufficient sleep.

jerlam• 5 months ago

Yeah, "get better sleep" is usually followed with "by buying this thing". No one makes any money if you go to sleep earlier.

debo_5• 5 months ago

My experience is being surrounded by people who sleep eight hours a night and then check their ring data or whatever nonsense to convince themselves that they could do better.

koalacola• 5 months ago

Is this your article OP?

aethrum• 5 months ago

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?

thenewnewguy3• 5 months ago

I'm not an MD or expert in this field enough to know if OP is right or wrong, but I think it's fairly reasonable to be irritated people are claiming software has a health benefit based on vibes/feels.

I thought we as a society had moved on from superstition to evidence-based medicine, but in this very post there are plenty of replies countering OP's scientific analysis and data with anecdotes (which is disappointing regardless of if TFA is correct or incorrect).

geoduck14• 5 months ago

I think it's fairly reasonable to be irritated people are pushing software based on vibes/feels.

You are going to HATE to find out about night-mode in the browser

jack_pp2• 5 months ago

Is it superstition to deduce that I get gassy after eating beans? I need a scientific study to tell me this? Same for if a screen hurts my eyes (not long term, like truly my eyes hurt) when using bright white colors at night.

bob1029• 5 months ago

I think it's fairly reasonable to be irritated people are pushing software based on vibes/feels.

https://en.wikipedia.org/wiki/Video_game_industry

taco_emoji• 5 months ago

I thought we as a society had moved on from superstition to evidence-based medicine

Surely you didn't actually believe that unless you JUST landed here from space after being away for 60 years.

KaiserPro3• 5 months ago

because if you read the article its about blue light filters to aid sleep not ease of reading.

The the grift wheel on this particular bandwagon is strong. To the point where my fucking glasses have a blue filter on them, which fucks up my ability to do colour work becuase everything is orange.

robinsonb5• 5 months ago

If you wait long enough cataracts will give you that for free.

cpburns20092• 5 months ago

Blue light filtering lenses come at a premium. You don't accidentally get them.

tartoran5• 5 months ago

I confirm that this helps me as well. Quite often I don't have any fancy filter, I'm permanently setting display/monitor to low temperature and my eyes/vision couldn't be happier. I don't even need darkmode, regular mode works just fine for me as long as blue light is toned down. Granted, I'm not doing any color correction or anything color sensitive work.

I used to have terrible headaches about 20 years ago when I started spending a lot of time in front of the screen. I went to an optometrist who tested my eyes and told me I could get low prescriptions (.5) but warned me that there's no way back and that many people are fine with my current vision, choosing not to get a prescription. Luckily I figured out that it was blue light that was bothering me and once I turned it down I haven't had any problems since. I'm in my mid 40s and my vision has naturally deteriorated a bit but I am still fine with no prescriptions.

And I don't believe this to be placebo. Every time I stare at a regular screen for longer than 5 minutes I get eye strain. At the same time I suspect this doesn't help everyone, but at least to me this is a great solution that still works.

cellularmitosis• 5 months ago

Can you elaborate on “no way back”?

amelius• 5 months ago

Are you sure you are not also changing total luminance?

refulgentis5• 5 months ago

They are, just, don't realize it. Anything off white will be < luminance than white. People replying they need it need to be turning their monitor brightness down.

himata4113• 5 months ago

I actually cannot use my monitor without nightshift, any white page just makes my eyes water, painful even. I had it off for a day when I switched to linux and immediately my eyes started drying out.

Safe to say it works for making your eyes less tired at least.

nsxwolf2• 5 months ago

I love Night Shift.

taeric2• 5 months ago

I find it somewhat pleasant, but by far the best thing I did to help my eye strain was greatly lower the brightness. Basically, I was told to make it so that my phone's camera could see something on the screen and my desk at the same time without washing out.

After doing that, I have found that the "temperature" of the screen doesn't really matter to me that heavily.

kpw94• 5 months ago

Basically, I was told to make it so that my phone's camera could see something on the screen and my desk at the same time without washing out

+1. The low-tech version of this I've heard and I've been doing is:

Hold a printed white paper sheet right next to your monitor, and adjust the amount of brightness in monitor so the monitor matches that sheet.

This of course requires good overall room lightning where the printed paper would be pleasant to read in first place, whether it's daytime or evening/night

DANmode• 5 months ago

Concur that most displays are set 25-50% too bright by default.

metalliqaz• 5 months ago

My Windows 10 PC glitches out most days where the 3rd monitor doesn't properly apply the Night Light setting. So I turn it off and on to fix it. The full blue brightness is awful and definitely harsh on my nighttime eyes. I'm not sure I could believe it's placebo

refulgentis5• 5 months ago

It is a placebo, it is an aesthetic thing. It is not something that helps anything at all physically.

This was always well known. It didn't matter 5 years ago, 10 years ago, when OS added it. Easier to let it go than argue.

But with HDR, it matters enormously people are well educated on this. Monitors are approximately light bulbs, and we've gone from staring into a 25W light bulb to a 200W one. (source: color scientist, built Google's color space)

What is the authors problem lol? It feels a lot better on eyeballs to use warm light things. Why does he care?

I think it's better to avoid stuff like this. Been here 16 years and a flippant "whats his problem" "lol" and "why does he care" is 99th percentile disrespectful. It's not about what you're arguing, its just such a fundamental violation of what I perceive as the core tenant of HN, "come with curiosity." You are clearly curious, just, expressing it poorly.

RupertSalt2• 5 months ago

username checks out

wtetzner4• 5 months ago

It is not something that helps anything at all physically.

That's a pretty strong claim to make.

schiffern• 5 months ago

Aggravatingly, you can't set Night Shift to actually be on 24/7. It always has a "seam" where it fades off and then turns back on.

One trick is to schedule this as a bedtime reminder to put down the phone for the night (phone fasting).

InMice2• 5 months ago

I kind of despise that part about nightshift, since i almost always like to keep it at medium anytime indoors and during winter. But in the later evening I want it max, and when i got to bed i want it even more. And ive always despised flux for that too. It's even worse since a lot of times i sleep in two phases each night and it doesnt allow to change the length of night time. So dumb.

In a way it's mildly frustrating, but also slightly insane to me that some of these things are so limiting in control. I cant just be given a simple on/off toggle? There is a project manager(s), paid millions collectively that sit in a room and decide "No, you cannot keep nightshift on, it will turn off at 7 AM every morning." Like... WTF.

Stuff like this just keeps on getting worse and worse - and more and more common.

Ive created shortcuts to jump directly to night settings and a shortcut to enable color filters. Still...

MBCook2• 5 months ago

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.

simoncion• 5 months ago

What is the authors problem lol?

I'm not the author, but every time I've seen Night Shift (and things like it) being used, they've done a grand job of royally fucking up the colors of whatever's on screen.

It feels a lot better on eyeballs to use warm light things.

That's, like, your opinion, man. The lights in my house are all 5000K lights, and I love it.

I expect you'd get way more out of reducing the brightness of your screen [0] than fucking with its colors. So many people seem to love having searingly-bright screens shining into their faces... I don't get the fascination.

[0] If you've got the monitor's brightness at minimum and it's still too bright, then there are software controls to further reduce it.

disillusioned2• 5 months ago

I respect that other people have the right to their opinion, but 5000K lights 24/7 is so completely insane to me. How? How do you get by with "dentist office mall kiosk" lighting blaring every hour of the day?

I have an adaptive Lifx bulb that changes from 5000K during the day and then shifts down to 3000K at night, before tapering down to 2700K for overnight and it's amazing. 5000K in the corner of a dark room is just so disjointed and intense and upsetting to me, if I stay at an Airbnb for more than a night or two and there are daylight bulbs installed, I'll literally buy replacement bulbs and change them out.

wtetzner4• 5 months ago

they've done a grand job of royally fucking up the colors of whatever's on screen.

Pretty sure that's the point?

tuetuopay• 5 months ago

Well he goes on to rant about how it changes the colors displayed by the monitor, so a publisher cannot show the intended color (cyan in the example).

Except he completely ignores that’s actually expected for a cyan object to be duller at night: it’s the albedo of the object and the perceived color will dramatically changed between daylight and nightlight. So the screen is more contextually correct by toning down cyan, and the colors we perceive will match (and reinforce) the circadian rythm: the user will recognize cyan.

Of course, doing color-sensitive work should not be done with such filters.

HumblyTossed• 5 months ago

It's not. I managed optical labs (the one hour kind) while getting my BSCpE. One thing I always used for my personal glasses for studying (the ones with an additional +.50 diopter for helping my reading - but that is another post), is about a 5% solid brown tint on the lenses to make the paper just a little less white.

pier25• 5 months ago

I took a sample of 4 websites/apps (Google, X, Github, and VSCode) with the SpyderX colorimeter + a diffuser to average over a larger area of the screen, and found reductions in luminance ranging from 92% to 98%! That’s huge.

What about TikTok or Youtube?

SoftTalker3• 5 months ago

I have my phone in monochrome (i.e. greyscale) mode and just subjectively it's much easier to look at especially at night. I have it at the lowest brightness and it's still very readable. Human eyesight is basically monochrome in low light settings anyway.

culi• 5 months ago

I have an accessibility shortcut to turn my screen greyscale with triple taps but I kept turning it off so I could see the clues on sudoku and now I've forgotten I even had this for almost a year

Low brightness is great though. I didn't realize most of the battery drain on a phone is often just the screen. Lowering the brightness to as little as I need has been great for battery life

cjbgkagh• 5 months ago

I use blue blocking glasses, like Bono but darker and they do work. I also use UV LEDs to help me wake up, which also works.

I agree with the premise that night shift and other color warmth features are insufficient to have a strong effect, though they do help with eye strain which is still a positive.

harrall2• 5 months ago

I firmly believe this varies between people significantly.

Blue light filters do not work for me because I fall asleep on command everyday all the time regardless if WW3 is outside.

BUT it also seems the effect of poor sleep seems to be MUCH worse for me than other people. I go from extreme motor coordination to dropping cups in a span of 3 days of poor sleep.

There’s a chemical called adenosine which accumulates over the day that induces sleepiness and there are genetic variations that can affect your susceptibility to it. Receptors notice the accumulation of adenosine and use it as a signal to “scale down.”

I think that I am more sensitive, explaining my ease of sleep but also the effect of it when it accumulates due to poor sleep (sleep flushes it away). Yeah it’s great when I’m in bed but it’s not great when I want to throw a ball and my brain wants to be stingy. It basically means that someone else’s “helpful guide to sleep” is completely different from my “helpful guide to sleep.”

lowdest• 5 months ago

the effect of poor sleep seems to be MUCH worse for me than other people. I go from extreme motor coordination to dropping cups in a span of 3 days of poor sleep.

Are you sleeping enough? When I was getting too little sleep, averaging 5.5 hours per night, this described me well. A single sleep interruption could make me lose most of a day of work. I'm sleeping better and longer now, and it seems I'm more able to tolerate small interruptions.

harrall2• 5 months ago

Yeah I’ve gotten 8 hours of sleep almost everyday for 15 years, ever since I put 2+2 together. In my early 20s, I didn’t like being bad at sports and I found sleep was my single most important factor.

Similar to you, I also noticed that if I miss good sleep for several days, it stacks. I treat sleep like a battery. A day uses up 20% and good sleep fills it back up, but only like 30%. One missed night isn’t that bad but I also can’t recover several nights’ worth.

mikkupikku3• 5 months ago

Why is it that a few people seem to get bent out of shape by redshift and/or dark modes? If you don't like it, don't use it. Whining about scientific evidence is pointless, even if it all only comes down to user preferences with no science behind it, so what? Let people enjoy things.

IAmBroom10• 5 months ago

Yes! Leave me and my mercuric-laudanum tooth-straightening sales alone! People like the taste!

ctbeiser• 5 months ago

It seems pretty clear in the OP that headline is misleading—they do work, just not as well as he would like. I think that a 50% cut in light emission is pretty good—and you can stack that with the other interventions listed, like auto-dark mode and reducing light in your room.

leni536• 5 months ago

Note that it's only 50% if you don't normalise back to absolute brightness.

nicoburns• 5 months ago

Blue light filters definitely work for me. But it needs to be a strong filter (quite a bit stronger than the strongest setting of Apple's built-in filter).

nomel• 5 months ago

Yes, article title is clickbait. Partial filters don't work, but as they suggest, 100% filter of blue light (resulting in no blue light present), DO work.

You can get this with Apple's strongest filter, the color filter, in Settings > Accessibility > Display & Text Size > Color Filters, rather than night shift. Only red sub-pixels are illuminated with it. It can be added to the triple click power button accessibility shortcut.

That's what I use. I have a shortcut set to enable it when I put my AirPods in at night.

Groxx5• 5 months ago

So the main claim presented here is that reducing blue reduces total "light" (lumens? watts?) by 50% (totally believable), and that reduction in light is all that matters for sleep?

That seems reasonable. The pseudoscience wankery that the fad has brought bothers me a lot too.

... but I'm not sure that's much of an argument against blue light filters, aside from color complaints. That seems to support that it's Useful and Good and is Achieving Its Intended Goal. It's reducing total luminance, because people prefer it over reducing screen brightness overall. I sure as heck do anyway (as night shift modes, they're a more comprehensive option than dark mode), though I think I'll experiment with just reducing brightness a bit.

----

For melatonin in particular, fully agreed. The recent trend of "can't even get <5mg in stores, and >10mg is appearing regularly" in the USA is mind-boggling to me. AFAICT it's exclusively because it's a "supplement" and therefore practically unregulated, and these companies don't give a shit about anyone they harm, just profit.

Start with something like https://a.co/d/0dISg7oa (0.3mg, this is what I personally use) and go up from there, slowly.

SoftTalker3• 5 months ago

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

Groxx5• 5 months ago

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.

gowld2• 5 months ago

No, in the OP (after an unclear intro that confuseed many readers), there is a graph that shows blue wavelength intensity is important, but software light filters don't filter a lot of it, and the effect is cancelled by increasing overall brightness.

Groxx5• 5 months ago

If software filters are reducing total light by 50% while only affecting blue-ish tones, and that's a total light level comparable to multiple brightness steps on a Mac... tbh I think it's reducing it quite a lot. Many I see using them (myself included) don't tweak brightness when enabling it, and many (all?) systems don't adjust their brightness to match the perceived change from a software filter (on my Linux machines in particular I have never seen this happen, don't know about Macs though).

Half is not a lot, sure, but their ultimate suggestion is to do the same ~half change:

You can decrease the amount of light coming from your screen by more than half simply by dimming the screen by several notches.

which is definitely significantly more than I see people doing voluntarily in the hundreds of millions.

Do they have any evidence that people are raising system brightness to match the 50% loss from the filter? If not, it still seems like a rather significant mark in their favor. Perhaps not sufficient to meet the goals (they seem to be recommending a larger change, but aren't specific), but I see no claim that a lesser decrease in light is worse.

---

Late edit: on second thought... let's go through this more rigorously. For both myself and any other readers, because I want to make sure I'm following it accurately too.

The main explicit points in this article are, in order:

- night shift does not help with sleep (the main claim)

- blue light is not special, in particular because the "[most] sensitive to blue" research is mis-quoted to mean "blue is bad", but it's actually sensitive to blue and green (seems very well supported)

- night shift reduces blue and green by about half (tested themselves)

- half of absolute is not a lot because vision and a lot of the related biology is logarithmic (100% agreed)

- halving light affects 25%-50% of melatonin levels (linked research)

- many people use Night Shift (100% agreed, and they have decent data to back it up)

- dark mode is better than night shift (>90% vs ~50%, implied leaning on the linked research earlier. agreed, seems straightforward)

- dimming your screen by several steps is the same or better than night shift (as it decreases brightness more, same reasoning as dark mode. agreed.)

That still sounds rather in favor of Night Shift. It's targeting the correct color range (NOT the pseudoscience blathering of just blue blue blue), it has a moderate affect on melatonin levels at the light level changes it creates, and it's used by a huge amount of the population.

Nowhere in there that I can see is anything to back up "Night Shift does not work". Only "it seems to be doing things right, it just isn't quite enough on its own" and "ARGH it's not just blue light STOP PROMOTING FAD PSEUDOSCIENCE". That seems... fine? Most things are not silver bullets.

ltbarcly3• 5 months ago

Well they work in that the color temperature of the light in my house is much cooler during the day than at night, and it's nice to match it so it doesn't look jarring.

pclowes• 5 months ago

You can just do things. Not everything needs a study, you don’t have to justify yourself to anyone!

Try things, if you like them, do them!

Try not living a neurotic “study” based life, I am trying it and its pretty great!

Barbing6• 5 months ago

(just nothing from Goop)

tartoran5• 5 months ago

Absolutely and this is something that can be tested rather easily. If blue filters aren't immediately helpful to eye strain then they probably don't work for you but if they are they probably do work for you.

IAmBroom10• 5 months ago

You can test the negative easily, but the positive is harder. Thus: placebos.

Perizors3• 5 months ago

Every dismissive reply talks about eye strain nada that is by far not what the author is taking about.

IAmBroom10• 5 months ago

I am aware that meta-studies of glucosamine chondroitin show No Significant Gains in joint pain. I would never waste my money on it.

But my newly adopted dog had hip issues, and I bought a few months worth of a diet supplement in the hopes of doing something meaningf... dammit, it's glucosamine.

They claimed double-blind studies showed decreases in limping in just two months.

Two months, more or less, I stopped seeing him limp by the time we left the dog park. He still does sometimes, but it's rare - not every damn day, by any means.

We aren't that fricking different biologically from dogs in our skeletal attachment system. Maybe it's still a placebo, but it seems to defeat that idea. Maybe enough human issues are based on things that don't translate to dogs - sitting at a desk all day, eating junk food, walking upright... - that it helps them, but not enough of us.

Don't know. These GC supplements have convinced me it's worth my money, and he loves eating them, so he votes 'yes', too.

rkomorn• 5 months ago

I found it interesting that placebo effect is also sort of relevant in pet care: it makes owners believe the pet is doing better.

Unfortunately, the study that showed this used the same medicine my dog had been on, and since it was for epilepsy, I can totally believe that whether I thought it worked had no connection to its effectiveness.

root_axis• 5 months ago

Neurotic is bad by definition, but using studies to inform your habits seems like a wise thing to do.

Obviously you shouldn't follow studies blindly, especially because many studies are poorly conducted and do not replicate, but in general, we know that just following your gut is suboptimal and sometimes dangerous in cases when studies give us clear information.

wtetzner4• 5 months ago

Unfortunately it doesn't seem to be easy to understand what studies are actually demonstrating, based on how often you see people making giant leaps to conclusions that don't really follow from study results.

stuckonempty4• 5 months ago

You can and should! Just don’t go justifying that your choices are rooted in science when they aren’t.

thrawa8387336• 5 months ago

What, you think Newton relied on a study to believe his own conclusions?

UqWBcuFx6NV4r• 5 months ago

Yep. This attitude is utterly pervasive. We may as well just give up and start saying “science says…”, the way some people, especially some people here, seem to misunderstand what role studies play, what their limitations are, etc.

Imagine if you have a rare genetic mutation that causes Night Shift to be extremely, extremely effective, and you don’t even try to use it because A Study Didn’t Tell You To.

You are indeed allowed to just…try things and see for yourself, especially such ostensibly low-risk things like this. The literature is not a bible.

erelong• 5 months ago

"This is the way"

I think the other problems are that some things aren't proven or some studies are wrong, so it doesn't eliminate making choices on certain topics without a study backing what you are to do (and then you can even defy the studies if necessary...)

pie_flavor• 5 months ago

If you aren't aware, your phone's screen can go much dimmer than the minimum brightness offered by the slider, if it supports HDR. There are apps that use an HDR screen overlay to lower brightness all the way down to the dimmest you can perceive. In my own experience, 'half' the brightness of 'minimum' brightness is plenty dark enough to not disturb sleeping at all if using my phone in bed.

Barbing6• 5 months ago

Also for third-party monitors with MacBooks: BetterDisplay

Can even use an external keyboard’s native brightness buttons. Can still use f.lux if desired too though Night Shift maybe Sherlocked there a bit…

lisper3• 5 months ago

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 time zone on my computer (because it screws up my calendar). But my sleep cycle continues to track my home time zone for a very long time. I life in California, but at the moment I'm in Hawaii. I've been here three weeks so far. At home I'd fall asleep around 11 and wake up around 7, but here I'm getting sleepy at 9 and waking up at 5.

My wife, on the other hand, is a hard-core night owl even with night shift. So apparently there is a lot of individual variation.

This article has inspired me to do a control experiment by switching night shift off. Check back here in a week or so for the results.

Barbing6• 5 months ago

inspired me to do a control experiment

Delightful, see ya the 27th!

lisper3• 5 months ago

So the results are in, and I haven't actually noticed much of a change. Last night I went to sleep after 11 and woke up at 5:30. So apparently night shift by itself doesn't have much of an impact one way or the other, at least not in a week.

gowld2• 5 months ago

Night shift seems to have a very strong causal effect on my sleep cycles.
light hygiene and using night shift

The OP article is primarily about separating the variables you lumped together.

nandomrumber7• 5 months ago

light hygiene

Awesome, hadn’t come across this term before.

You might appreciate the concept of chronotypes.

https://en.wikipedia.org/wiki/Chronotype

The DOAC podcast recently hosted Dr. Michael Breus on same.

Apple Podcast link, or conjure your own:

https://podcasts.apple.com/au/podcast/the-diary-of-a-ceo-wit...

Perizors3• 5 months ago

Bear in mind that chronotypes, as stated in the wiki, only varies about 2-3 hours from each other. This is just to say that there is no nocturnal person in terms of biology, we are all diurnal mammals after all.

lotu• 5 months ago

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.

Barbing6• 5 months ago

Been more careful with my lighting this week :) how’s yours?

lisper3• 5 months ago

https://news.ycombinator.com/item?id=47185525

crazygringo5• 5 months ago

These are the kinds of articles that give science a bad name, and that make people anti-science.

You might as well try to claim hot tea doesn't help you get to sleep, or reading before bed doesn't, or whatever else you do to wind down.

I personally don't care if some narrow hypothesis about blue light and melanopsin is false. I know that low, warm, amber-tinted light in the evening slows me down in a way that low, cold, blue-tinted light does not. That's why I use different, warmer lamps at night with dimmers, and keep my devices on Night Shift and lower brightness. It works for me, and seems to mimic the lighting conditions we evolved with -- strong blue light around noon, weaker warmer light at sunset, weakest warmest light from the fire until we go to sleep. Maybe it doesn't work for everybody. That's fine. But it certainly does for me.

And maybe it's not modulated by melanopsin. Or maybe it's not about blue light, but rather the overall correlated color temperature (CCT), e.g. 2100K instead of 5700K. Who knows.

But this type of article is bad science writing. It shows why one hypothesis as to why a warmer color temperature would result in one other physiological change isn't supported. That doesn't mean "blue light filters don't work" as a universal statement. It's hubris on the part of the author to assume that this one hypothesis is the only potential mechanism by which warmer light might help with sleep.

And it's this kind of science writing that turns people off to science. I know, through lots of trial and error and experimentation, that warm light helps me fall asleep. And here comes some "AI researcher and neurotechnologist" trying to tell me I'm wrong? He says it's "aggravating" that people are "actually using Night Shift". I say it's aggravating when people like him make the elemental mistake that showing one biological mechanism doesn't have an effect, means no other mechanisms can either.

AshamedCaptain5• 5 months ago

These are the kinds of articles that give science a bad name, and that make people anti-science.

No, it is attitude like yours that brings humanity a bad name.

"Blue light effects" have always had highly questionable evidence behind it, what has been sold and marketed under the guise of it has had _zero_ evidence behind it. But now that you are reminded that it is actually bullshit, you react with skepticism.

"Feels good to me" is hardly evidence to begin with. It's something that is even more flimsy than sociology. I have my doubts it should even be called medicine.

You have to remember that a shitton of people day after day "show" "evidence" that homeopathy works. Even though it has no plausible mechanism of action. So clear mechanism of action is about as important as the evidence itself. (see Science-based medicine)

I could understand (not justify) skepticism in many cases (such as "common wisdom" from 1000 years ago) but this particular topic should have raised your skepticism 20 years ago back when the craze/marketing stunt was starting, and not now.

chuckadams2• 5 months ago

Someone says that other psychological factors (which have physical effects) help them sleep and they "bring humanity a bad name"?

Maybe think on that a little bit.

crazygringo5• 5 months ago

"Feels good to me" is hardly evidence to begin with

Where did I say anything like that? Please don't mischaracterize my comment, that's not helpful. It's not that it "feels good", it's that it helps at least some people fall asleep more easily, and I know this from personal experience. And many, many other people have written that it does the same for them.

"Blue light effects" have always had highly questionable evidence behind it... But now that you are reminded that it is actually bullshit

You're right that the evidence for it is questionable. But you know what else there's no conclusive evidence for? That hot herbal tea helps you fall asleep. Or soothing music. Or bedtime stories. Because the funding usually isn't there to perform the kind of large-scale studies required to establish these things, because it's just not a priority or even a good use of our dollars. And lack of evidence for, is not the same as evidence against.

My point is, nothing in this article does establish that it is "actually bullshit". That's a gross misreading of the science, and that's what I'm criticizing the article over.

People experiment with things and discover what works and what doesn't. Again, nobody's going around complaining that there's no scientific evidence lullabyes don't help put you to sleep. And neither lullabyes, nor turning your lights down to amber, have anything to do with homeopathy. You can't possibly suggest they're doing harm. People aren't using amber lighting at night instead of getting their cancer treated.

But for some reason, low amber lighting to help with sleep makes you and the article author upset? Why? Why does that make you upset, but not hot tea or lullabyes? Or do those make you upset too?

anonymars• 5 months ago

But this type of article is bad science writing. It shows why one hypothesis as to why a warmer color temperature would result in one other physiological change isn't supported

I don't know if I'd even give them that credit (emphasis mine):

Halving the luminance, at best (around 20 lux baseline) might get you from 50% to 25% melatonin suppression.

orbital-decay• 5 months ago

What if these filters also cure cancer by some mechanism that isn't known yet? Who knows, it might be true! After long experimentation with warmer lighting my cancer is gone, so it definitely worked for me.

What you're saying is not science either. The entire medical usage of blue light filters hinges on just a few papers. If you really can prove those studies inapplicable you can prove that there's no objective reason to use them (I'm not necessarily saying the author did that).

Whether these filters feel nice is entirely unrelated question, nobody stops you from decorating your living space as you see fit.

wa008• 5 months ago

Based on my experience, most health benefits are from personal habits over external hardware. But people care health so much, it's a great opportunity for merchants to get revenue.

alejohausner• 5 months ago

I bought some amber glasses from blublocker.com[1], because they link to a research paper that actually measured how much of each wavelength their filters allow (as well as other brands). They're pretty dark, so you have to crank up the brightness on your screen, but I'm confident that I'm not getting ANY blue.

1: https://www.blublocker.com/blogs/news/what-blue-light-blocki...

kb9alpp• 5 months ago

Nice. The article also mentions BluTech lenses (BluTech LLC, Alpharetta, GA). I've found the marginal utility of bluelight blocking solutions are very context specific, indeed. And mostly-completely bahokie garbage, sadly, but not when it's BluTech and BluBlocker. BluTech/BluBlocker for the screen-induced fatigue is the correct solution. I always get BluTech HI Indoor AR pucks for my prescription lenses. And just switch to prescription sunglasses when I go outside.

stuckonempty4• 5 months ago

Those glasses state that they are the only pair that “blocked 100% of harmful blue light in the 400-450 range”

But melanopsin contained in the cells that regulate circadian rhythms have an absorption spectrum extends to slightly beyond 540 nm (see the OP’s post). As the author says, “It’s not sensitive to blue, it’s sensitive to cyan (and blue and green).”

Those glasses probably do what they say in terms of wavelengths they filter, but they are only partially filtering out light relevant for circadian rhythm regulation and sleep.

cptskippy• 5 months ago

I have Night Light perpetually on with all of my devices because I find it softens everything and makes viewing displays less harsh, less garish, less vivid, and less intense. I don't need eye searing HDR constantly cooking my retinas.

yathern• 5 months ago

Unless your strategy is to create a photo-lab-like screen in pure black and red, or wear deep-red-tinted glasses, it’s unlikely that a pure colorshift strategy will cut out that big of a chunk of the spectrum.

I absolutely think this is the right approach. The glasses which do 'blue light filtering' which barely change your perception are clearly placebo, but a very strong redshift I think is obviously a different creature.

EA-3167• 5 months ago

Absolutely, although dark orange seems to work well enough. If you can put them on and still tell the difference between most colors, they aren't working. I use my pair for one purpose: reading in bed with a backlit e-reader. I can't imagine trying to do much else with them on, they have plastic wings to block light from the side and they're not light.

But they work.

hinkley2• 5 months ago

I have a red flashlight I use at night to read books. It’s weird after an hour I don’t really see it as red anymore, just dim off white.

zcw100• 5 months ago

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.

nandomrumber7• 5 months ago

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.

Marsymars3• 5 months ago

This is especially nice if you use bulbs that get warmer as they dim. (See the Kruithof curve.)

TACIXAT• 5 months ago

I have had success with an extremely aggressive red filter. My unchecked sleep schedule has me going to bed around 4 am, consistent over decades. I don't consume caffeine or any other stimulant. In the last 4 months I switched my lights to LED bulbs to turn red at 6pm and use QRedshift on Linux (Mint) with the temperature set to 1000k at 6pm. I have consistently been falling asleep around midnight. What is remarkable to me is that I am actually feeling tired at night.

jrm4• 5 months ago

It's funny, I'm so comfortable calling this guy an idiot purely based on the fact that I've taken up Bob Ross style painting in like the last 2 years.

Teaches you to pay attention to "objective" colors. And at night, guess what, the colors get more red and less blue. I don't have to pull out as much blue paint for the night scenes.

It would be utterly naive to not thing that there's -- perhaps purely "psychological" (not sure if that's the exact concept but hey) effect by making the "white" on your screen, look like like the "white" you will definitely see in real life, which is going to be orange-r.

iainctduncan• 5 months ago

Regardless of the sleep effect (or lack of) they absolutely do work for reducing eye strain for migraineurs.

It's noticeable to me all the time, but if I'm borderline migraining, or recovering from a migraine, the difference between shifted and not is something I can feel instantly. Shifting all the way over enables me to eek out some work after a migraine without it flaring back up again.

Waterluvian• 5 months ago

I really don’t care if they “work” or not. I find it incredibly cozy to have a warmer, calmer screen in the evening.

reenorap• 5 months ago

The entire blue light madness is based on a poor study where N was around 8. And the difference in sleep was something like 15 mins. The entire study was based on crap but somehow the entire world has run rampant on the idea that blue light has this profound effect. It just goes to show that bad science is easily propagated, even when there's even more sources of information.

Marsymars3• 5 months ago

I don't know enough to defend the study, but I don't think 15 minutes of sleep is insignificant. If I'm consistently woken up 15 minutes before my normal wake time it's going to have a negative effect on me.

baud96002• 5 months ago

I added the “Noir” extension to mobile Safari, now I automatically get dark mode on all websites including Hacker News.

hinkley2• 5 months ago

I’m surprised by how may don’t have a dark mode though. I decided to do it for my blog despite not really using it myself, and ended up sticking with it on. Still getting blasted in the face by eggshell white everywhere I click.

the_pwner2242• 5 months ago

"Dark Reader" does the same thing on desktop Firefox/Chrome/etc. (& mobile Firefox, maybe also available on mobile Safari?).

baud96002• 5 months ago

Mobile Safari only does this for sites that implement dark themes (and when you have dark mode enabled in iOS). But many sites don’t have these themes. The Noir extension seems to fix the problem for now. There is a reader mode that can go dark but it’s manual, per article

james_marks• 5 months ago

I have a triple-click shortcut in iOS to use the accessibility features to go below the min dim settings.

Otherwise even dark mode is way too bright in a dark room.

hn_throwaway_996• 5 months ago

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.

galangalalgol• 5 months ago

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.

UlisesAC4• 5 months ago

I can absolutely confirm that night mode works wonders. Since ten years ago I discovered them I no longer have dry eye like problems.

stuckonempty4• 5 months ago

Did you read the article? He points out “It’s possible that Night Shift does something, but the biggest study I could find of Night Shift mode (still a pretty small study) found little effect on sleep, so if there’s an effect, it must be tiny.” He links the exact type of observational study you asked for

Regardless the maximum possible effect will be constrained by the biology of the cells responsible for responding to blue light. Maybe knowledge of the biology is incomplete or flawed but to not use it to inform what’s possible seems foolish.

So what if it’s a placebo effect? Well some people are spending money and time investing in blue light filtering glasses and other solutions. It’s potentially snake oil and it could keep them from pursuing better solutions that would actually help them sleep

Griffinsauce• 5 months ago

That sentence does not give me a lot of confidence. The conclusion does not follow the initial statement at all.

hn_throwaway_996• 5 months ago

If the author goes "I couldn't find enough high quality studies on the topic I'm discussing", then the conclusion should be that we need more studies, not to come to unwarranted conclusions in the absence of actual data.

Well some people are spending money and time investing in blue light filtering glasses and other solutions.

Ironically, we actually do have a number of good studies on the effects of blue light filtering glasses (easily findable with a Google search) and they do demonstrably reduce onset of sleep time. Where more research is needed is on software-only filters for screens.

guelo• 5 months ago

But you could make your same argument for the pro blue light filter side.

hn_throwaway_996• 5 months ago

Sure, and I'd write the same thing if we were talking about a blog post that said everyone should use blue light filters because of some plausible physical mechanism.

energy123• 5 months ago

Blue light blockers are a scam that was created when some circadian rhythm research went viral (in a highly misrepresented way) online a few years ago. It's a stunt to make some quick cash from unwitting buyers.

storus2• 5 months ago

My Gunnars give me immediate eye relief after a day of work looking at a display. Are you sure it's a scam?

hn_throwaway_996• 5 months ago

"It's a stunt to make some quick cash from unwitting buyers."

I've used a number of blue light filters, and I've never paid for them.

accidentallfact2• 5 months ago

Even the premise of the idea is wrong, as evenings are either blue from the blue sky, or white from the clouds. It takes exceptional circumstances to have a reddish evening, and even then it's just around the sunset.

I guess that it may help people with undercorrected myopia due to the chromatic aberration, but, I don't know.

gurkenkram• 5 months ago

It is indeed about the sunset and especially the last phases of it. It's also why red light is recommended for night feeding when breastfeeding.

Works for me, both reducing the blue light and worked for my baby, too, using only deep orange and red light of a cheap LED color change lamp. Apparently works for many, since red nursing lights are suddenly sold everywhere.

bawolff2• 5 months ago

When the sun goes down the amount of blue light goes down. Are you disputing that? Respectfully this feels like a crazy claim.

mock-possum• 5 months ago

Plus there’s a lot of protein eggs, so they’re filling, and have to eat less to feel full, resulting in less food consumed and therefore less opportunity to intake further sources of cholesterol

daneel_w2• 5 months ago

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.

MBCook2• 5 months ago

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.

daneel_w2• 5 months ago

So which do you think it really is? Cutting two wavelengths' outputs in half, or reducing them by a mere 1% as per your trifling comparison?

unparagoned2• 5 months ago

And when you combine that on top of dark mode and dimming screen that does make a real difference.

scythe• 5 months ago

The argument about luminance ranges is wrong. I measure the brightness of monitors regularly as part of my job, and typical maximum luminance values are in the range of 100-500 lux. That puts you right in the steep range of the visual response (especially if you are turning it down and near a max of 100), which is natural — maximizing the slope of the neuronal response to light means that more information will be available to the brain. In fact a good monitor will be tuned according to the just-noticeable difference which aims precisely to maximize the information available according to this characteristic curve. See e.g. the DICOM standard:

https://dicom.nema.org/medical/dicom/current/output/chtml/pa...

The author's basic problem is that he knows too much about the brain and not enough about monitors.

The author goes on to argue that you should be turning your brightness down, but most people already are turning their brightness down; the blue light filter is more comfortable. He does make a reasonable case that you should be reducing green light similarly, but people prefer the incandescent effect of the flux filter to a straightforward color filter — indeed a primary design goal of these filters has been to be pleasant to look at which is why people use them.

SubiculumCode• 5 months ago

I get frustrated with my dim and red shift app that is the default on my android phone for neither being very red nor very dim...but it's the type of app where every scammy body will put a red shift app whoch sucks up your location, contacts, etc, so I haven't changed.

buggymcbugfix• 5 months ago

That’s all great, but there are websites that still don’t have dark modes.

Such as that very website? ;)

zdc1• 5 months ago

I recall studies showing that reading in poor lighting conditions is a cause of myopia in children. So I'm questioning whether we want to be reducing luminance on our devices at all.

I like my (warm-coloured) lights and screens set to max brightness. I find it's easier to read and lets me work with more distance from the screen.

But what about easier sleep? Could we exercise more? Leave screens out of the bedroom? I have no idea.

zargon2• 5 months ago

Significant outdoor exposure is essentially the only relevant factor for preventing myopia. I would be interested in seeing any studies that showed any meaningful relevance of low light reading, while controlling for time spent outdoors.

avadodin2• 5 months ago

Main factor is genetics.

I was gaming on a blurry CRT and reading on a dim light while hardly ever going outside during my teens and I only have light myopia on one eye.

I don't know if it has ever been studied, but I suspect eye socket morphology from my own family anecdata.

large eyes + small socket = squashed eyes.

It could be different genetic factors for different populations too.

Melatonic2• 5 months ago

Best thing to actually do is use as dim a screen as possible closer to sleep. You can do this with external monitors using DDC and actually directly control the physical backlight of multiple monitors.

Also properly color calibrate your monitors

icar• 5 months ago

I actually get head ache after a long session in front of my computer, but putting anti blue light glasses it goes away or never happens.

lloeki• 5 months ago

Is half a lot?
No. Human light perception works on a log scale, allowing us to maintain useful vision over 6 orders of magnitude of luminance, from the sun at noon to moonless nights, whereas halving is .3 orders of magnitude. In relative terms, halving light is a tiny blip of the dynamic range of vision.

Kind of missing the point that:

a) a display emits spectacularly less light than the sun, even on very overcast days

b) said "blue light" reduction is presumably intended to happen at night where 1) any comparison with the ability to maintain unsaturated vision in plain sun on a clear day is largely irrelevant and 2) backlight itself is typically lower than in daylight (not for OLED which does PWM)

So given that the amount of artificial light to not screw up with sleep is about equal to "none at all" I'll take a cut in half of what essentially constitutes a flashlight aimed straight at my retinas any day.

Here are four things that can help. [...] Use dark mode [...] found reductions in luminance ranging from 92% to 98%! That’s huge.

From my anecdotal experience dark mode and other low contrast themes are mostly used by people who set their brightness too high, and conversely people switching to dark mode immediately crank brightness up.

Countless discussions I had:

"my battery holds poorly"

"using dark mode?"

"yes"

"try light mode"

"but my eyes!"

"turn brightness down"

"done. wow I just reclaimed 1-2h of battery"

metalman• 5 months ago

my phone has a buried setting for ultra dim, which does help, except outside, where it makes the phone unuseable, and then it's impossible to do the 5 taps and scroll to find it, fuck android going to a linux phone

duttish• 5 months ago

This is just my own anecdotal experience but I usually get tired around 2130-22 but a few times I've turned off the red filter for various reasons (photo editing etc) and suddenly I'm still there at 0030-01.

I'm not saying it's like this for everyone, but it seems to work very well for me at least.

pvtmert2• 5 months ago

Interesting take for me is that melatonin (over-)usage can be severely harmful for the individuals.

  ... over-the-counter melatonin supplements can contain anywhere between 10 to 30 times as much melatonin as is optimal to maintain circadian hygiene. If you have ever taken melatonin and got immediately knocked out cold, had weird dreams and woke up in the middle of the night sweaty or shivering, you likely took too much—which, to be clear, is not your fault, it’s the default in the US and Canada. The mega-doses in stores serve as hypnotics (punches you to sleep), but wreck sleep architecture. The right dose is ~0.3 mg, which is hard to find in pharmacies but can be found online.

IAmBroom10• 5 months ago

The right dose is ~0.3 mg,

I've heard this before, but the only metastudy I could find strongly supports a dose of 3 mg 3 hours before bedtime. Dose effectiveness effectively halves when taking less than ~2 mg or more than ~10 mg.

https://onlinelibrary.wiley.com/doi/10.1111/jpi.12985

xmodem• 5 months ago

Unless your strategy is to create a photo-lab-like screen in pure black and red, or wear deep-red-tinted glasses, it’s unlikely that a pure colorshift strategy will cut out that big of a chunk of the spectrum.

The writer is dismissing this out of hand but to me this sounds like a great idea.

pvtmert2• 5 months ago

My overall take (elephant in the room): Blue light filters don't work, it depends on what you do & how you do it.

For example, most people keep watching/scrolling Instagram Reels and TikTok videos. They keep stimulating the brain constantly, not just at electrical level but also in emotional/chemical level too.

I have seen people who are addicted and cannot get rid of the addiction. This is not only the dopamine-boost, it has deeper connections of neuro-chemical stimuli. Just observe around you; people pick up their phone to directly open Insta/TikTok, start scrolling right away every 5-10 seconds. (watching stories included too)

This is to some extent that when you mention even the possibility of such addiction and abnormal behavior, one gets outright resistance and denial of addiction itself. Much like substance abuse...

My point is, majority of the population watches/scrolls these, needing 10g of melatonin to fall asleep.

Obviously if I get engaged in an interesting stuff continuously, the existence of blue light does not matter that much. It matters if/when I am reading a novel which is in a mediocre chapter where nothing that interesting going on. The existence of blue-light or lack thereof may tip the scale at that point.

rcore• 5 months ago

That’s all great, but there are websites that still don’t have dark modes. It doesn’t make any sense in 2026 that Gmail doesn’t have a dark mode. If the activity you’re doing most at night is reading email, you might consider an alternative email client.

This reads funny on a website that does not respect your device's dark mode. Guess I'll look for an alternative blog.

jedberg• 5 months ago

It doesn’t make any sense in 2026 that Gmail doesn’t have a dark mode

I've been using dark mode on gmail for years, not sure what OP is talking about here.

But also, my sleep quality got much better when I turned on f.lux. And it got better still when I added a second light to my bathroom that can do a 1800K super-warm light (that's also very dim).

And as an added pro-tip, I use f.lux during the day to cut my color temp to 5900K (instead of the default 6500K) and it made a huge difference for how long I could work without getting tired eyes.

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

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