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Chemists discover how blue light speeds blindness (phys.org)
851 points by maxwell 45 days ago | hide | past | web | favorite | 332 comments



f.lux author here, still slogging through the article. It is hard to understand the light levels used because they use "power" (uW, mW) from a laser, and not "irradiance" (uW/cm^2 or mW/cm^2), so which area they have concentrated that light over is hard to understand. All I can see is it is from a laser, so the irradiance could be extremely high.

The human lens filters most light at the peak of the given spectrum for free retinal (383nm), and so once you get to 450nm like an LED, the hazard data in the visual range is 100x less sensitive, see Fig 1 here:

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097....

It bears repeating that computer screens have <5% the hazard-weighted irradiance of a blue sky. (Can't make a direct comparison with lasers.)

Not sure the conversion to white light is correct, and it is unclear to me right now if this much retinal is available in vivo.


Thank you for your input, but I mostly want to thank you for f.lux. It has been one of my favorite things for a long time. It's silly how long it's taken companies to provide a native blue light filter and your product just kicks ass.

If you guys ever wanted to figure out your app on a smart TV (or apple TV), I know there'd be a lot of thankful people!

Also, I'd love to contribute to the ongoing dev of f.lux (I don't think I've had to pay for it?) How might I?


Check out the FAQ for a PayPal donation link:

https://justgetflux.com/faq.html

Huge thanks to the author from me as well!


Thanks for telling me :) Paypalling now


thanks for the link. I have been using flux for years and recommending it to my friends too.. just donated a small amount..


On the AppleTV go to Settings > General > Accessibility > Display Accommodations > Light Sensitivity.

Then you can assign it to the Accessibility Shortcut and turn it on or off by triple pressing the Menu button.


Can't wait to do this tonight! This will help so much


Hook your TV up to a computer running f.lux or similar! I've used a HTPC for the past decade and more, wouldn't go back.


For my Samsung TV I use movie mode and also change colour temperature to warm.


I have the "blue light filter" on by default, on my android mobile. Don't know how effective it is, but it will at least help a bit.


On my Google Pixel, this is under Settings > Display > Night Light.


In Android Pie, it's also one of the 9 shortcuts you get when you pull down from the top twice on your home screen, right next to airplane mode.


I just want to remind everyone that LED backlights emit blue light that isn't eliminated by f.lux or similar utilities.


You might want to refer to our measurement project for some numbers:

https://fluxometer.com/rainbow/

Also, you can be below threshold for circadian responses just by being very dim.


Looking at your measurement, if I understand it correctly, you are saying that OP is incorrect and flux does in fact reduce the blue light?


Can you explain this more? If LED backlights emit multispectrum light (to get a white), and the LCD display filters those spectrum via RGB selection (say, letting less blue through, and more red/green), wouldn't this effectively filter the blue spectrum?

I know very little about this so I'm genuinely curious.


So if a new macbook pro has:

"15.4-inch (diagonal) LED-backlit display with IPS technology; 2880-by-1800 native resolution at 220 pixels per inch with support for millions of colours"

What possible laptop alternatives are out there that are better for eyes?


If you are curious, the smallest doses where "blue light hazard" has been observed in humans (short-term exposure) are around 10 J/cm^2. International standards use around 2 J/cm^2 for a safety margin.

One example of this is hiking in fresh snow for hours, no sunglasses, meaning exposures well above 10,000 cd/m2 to "white light".

Computer screens are way dimmer - an hour of iPad use is .0365 J/cm^2.

http://www.nature.com/eye/journal/v30/n2/full/eye2015261a.ht... is a good summary.

For long-term exposure (AMD risk) we have very little data, so understanding the mechanisms (such as above article does) can help.


Do those numbers account for pupil dilation?


Hijacking this for a moment to say thanks for f.lux :) I've been running it for years and it's one of those things where you don't really notice the effect until you turn it off and then EGADS MY EYES.


Windows 10 has this built-in, so does macOS.


I assume you mean the night light button in the action center?

If so I would argue f.lux does a lot more. For one thing you can choose the hue it goes to, but also unlike the Windows 10 one which (AFAIK) is simply on/off, f.lux will adjust based on a schedule which means that you don't typically notice the effects (as the change happens slowly). This, combined with the ability to change damn near every parameter it uses, makes f.lux significantly better.

Edit: apparently windows does have hue adjustment and sunset/sunrise activation/deactivation available. TIL.


Both macOS and Windows 10 has on/off now, scheduling, less/more warm adjustment. Windows 10 even has sunset to sunrise based on location.

EDIT: HN is becoming more like Reddit every day, I see. Ridiculous. Down-voted for pointing out the existence of helpful features. EDIT: might have been my fault.


Probably you were down-voted because of you starting with "What you are saying is wrong." People probably didn't like your tone and the original comment was only somewhat inaccurate. There still are more features in f.lux than the built in options.

And I assume you understand that since you edited that line out.


Correct. I realized that opening line set the wrong tone and was unnecessary.


I know these features exist in some places. But nobody had it before f.lux. And it's still - imo - one of the best implementations.


f.lux screwed up how my MBP displayed graphics so I'm just using the built-in tool now. Unfortunate.


IIRC that's a bug in the Intel graphics driver or something. I ran into that in the past as well and it's not directly f.lux's fault.


There was nothing wrong with your tone.


Night Shift on iOS and macOS also has a sunset-to-sunrise setting.


You'll almost certainly get down-voted on HN for whining about being down-voted, and for comparing it to Reddit.


Just checked. Also Mac OSX has Sunset to Sunrise based on location.


I've been a flux user for years, but sadly I had to switch to the Windows 10's version. Flux causes a 1 frame lag every 60 frames which was driving me crazy. Only fix was to put it into Safe Mode, but Flux is really janky in that mode; especially when alt tabbing. The Windows 10 version also has no lag while shift colors. It's a shame. I'd love to have kept supporting flux.


Our 2010 version polled once a second to get around a lot of bugs (Intel GPUs back then would forget their color settings on standby and lots of other things).

Since our update last year (v4) f.lux stopped doing this and does a lot of other tricks to reduce impact on framerates too.


Too bad neither f.lux nor the Windows 10 version properly support color profiles. f.lux has some support, but it sucks. And the Windows 10 version just outright has NONE. :\


These are relatively new features, and they arguably wouldn't have been added if not for the popularity of flux ;)


Does that matter? It's built-in now, and that's why I commented. To raise awareness. If built-in features have you covered there is no point going third-party.


I understand where you're coming from but they don't have feature parity. Flux allows me to target much lower color temperatures than MacOS' built in "Night Shift" feature. That alone makes Flux worthwhile.


Does it take a long time to get used to that? For me, Night Shift at full warm makes some websites difficult to use due to the change in color. I can't imagine going even warmer.


out of curiosity, how low are you going in terms of temperature?


It's nice that they are there for people who won't install 3rd party software to get the extra features, but f.lux is still better.


I would argue that if some software is under a free (libre) license, it's worth using over [non-free] first party stuff. This doesn't apply to f.lux, but does to redshift.


I would argue that it is only because of f.lux(and it popularizing the blue=bad idea) that MS/Apple/Google put this ability in their products. The technical ability to do such a thing has existed for ...decades, but no one ever did it until after f.lux came out.


So does Fedora, courtesy of recent versions of GNOME with "Night Light" feature.


Ubuntu got that too with the switch to Gnome. Before that, I used the open source https://github.com/jonls/redshift


ChromeOS has this feature for chromebooks now as well under the experimental flags section in case those users miss f.lux too. You can go to chrome://flags and search for Night Light to enable. As others have mentioned, I would rather use f.lux but (and my memory is hazy on this) I think the f.lux creator said the ChromeOS folks were not providing something he needed to get it working right.


I wonder from whom they took the idea? f.lux has been around for YEARS (2009)


Also, this was done on cell lines in vitro, only one of which was derived from a non-diseased human retinal epithelium (ARPE-19). Cell lines have undergone genetic change that allows them to replicate indefinitely, so they are fundamentally different from normal cells.

I presume that they used a laser because they anticipated that it would potentially take years to see a result from a non-coherent blue light source, far exceeding their available funding, patience, and ability to keep uncontaminated cell cultures going.

Applying a blue laser with unknown irradiance to a retinal cell line from a single human genetic source in vitro is very, very far from proving a link between blue light and diseases such as macular degeneration and RP.

All this demonstrates is that coherent blue light is capable, under certain circumstances, of interacting with retinal to produce cell damage.

Any relationship to human disease on the basis of this paper is pure speculation. Advising people to wear "blue blocker" sunglasses or avoid cellphone screens (or take Vitamin E!) is pure fantasy made up by the scientific press to sell your retinas.


Great analysis of the paper’s experimental protocol.

Isn’t the other “sniff test” that we haven’t seen a huge increase in age related retinal diseases since the introduction of computer monitor and handheld devices?

If these sources had such a big impact, it would be obvious from incidence numbers.


The problem with this is that the desktop computer being widely used is probably the late 1990s (and we should be isolating for screens that emitted the white light/blue light mentioned. Assuming that it takes daily exposure over a number of years say 20 years, we should probably start seeing that within the next 5-10 years from tech industry workers. It may be as severe as tobacco or as benign as fluoride, we'll see early indications, but we won't know until much later. I think everyone just likes it when it feels better for your eyes to filter out blue light.


I wanted to leave a note for others to keep in mind that f.lux can make the computer screen TOO comfortable to read in the evening. Which can lead to eye strain.

I used f.lux for 2 years. I found that I would stay up way past my bedtime, glued to the computer screen, and end up with correspondingly tired & fucked up eyes.

So I got rid of f.lux, and after that, I would go to bed at a more proper time. When the screen starts irritating my eyes, it's a direct indication that it's time to close the computer and get the hell to sleep. Ever since that, my eyes have done a lot better, because I no longer push to stay up way past my bed time.


I also tend to have eye strain if I'm computing very late at night, and take it as a signal to go to bed. I've described this to people, and it seems it doesn't affect everyone. It could also just be that there's a difference in awake time, blink frequency, or some other factor. I'll often go to bed more because my eyes are giving up on me and starting to burn rather than any sort of mental fatigue. I don't always keep normal daylight hours, so read this more as staying awake a long time than something specific to daylight


The pain signals of eye strain doesn't seem to hit right away, so I can keep reading past the point where I really should stop. The pain creeps up gradually but it's really too subtle if I'm stuck on an engaging story. But I don't have that problem if I turn off f.lux, that way my discomfort is more immediate and I stop.


What you described is exactly how I've been feeling for last 3-4 years. The pain signal kicks in the next day, sometimes even a day after. So yeah you can't tell at the time you're working late how the eyes will feel the next days. Sometimes it also triggers a headache and that spoils the whole day.

So the only solution I have figured is to be regimented about my screen time. I love working late at night and now have to tell myself to turn the work off. That kinda sucks.

Btw, It happened both with my previous laptop with LCD screens and the current LED screen.

For a few months I got hooked to Mobile gaming, and that just multiplied the problem! So I drastically cut down on my mobile time and that helps. My mobile had an LCD screen btw; so LED or LCD doesn't seem to be a factor for this particular problem.


I also ended up getting prescription glasses (really mild correction) to reduce eye strain when staring at computer screens. I only wear the glasses when looking at computer or phone (ideally, but not always).

I also found retina display helped reduce eye strain.


I suffer from chronic photophobia thanks to Uveitis. Flux allowed me to keep my job.


I'm running f.lux on my work PC (tones down a bad otherwise VERY bright-blue monitor).

Thank you for reading/writing out your interpretation of the article so clearly (highlighting points others are likely to trip on not coming from a related background)


Have we fixed the “optimized for electronics store demo” problem with monitors yet?

Part of my ritual of setting up a new monitor is to turn down the brightness and increase the contrast. They almost always default to very bad values. Brightness, temperature and green/blur balance are all off for an office setting.

In the worst case the backlight was capable of outputting twice as much light as I really needed.


When I got my first LCD monitor, the first thing I did was turn the brightness down to 0 and the contrast to slightly above; at that point it was already plenty bright enough, and after a few years when I noticed the brightness begin to fade I increased it 2-3 notches.

I suspect part of it is also planned obolescence --- when the backlight is running at full brightness, its lifespan is greatly decreased. Now the aforementioned monitor is approaching 15 years of age and brightness has reached 20/100, so there's still plenty of life left in it.


Leds often dim faster when young. Something else will most likely fail before the leds are too dim. On the other hand flickering can be more obvious if you lower brightness of a led. Brightness is usually emulated by turning the led on and off very fast.


Most/all modern monitors have presets, one of which is "store demo". All you've got to do is pick the calibrated preset.


Hey since I have you here, please, can you add support for proper color calibration, profiling & characterization to f.lux? Or at least outline in more detail how f.lux handles color profiles?

I wouldn't mind having to create multiple display profiles for this, but right now, flux seems to only support non-LUT based, Matrix based calibrations and only if they have VCGT headers, and then only based on those headers.

But this seems highly problematic.

Take a look at this page here for why:

https://argyllcms.com/doc/calvschar.html

I assume you based the current mechanics of f.lux when it comes to handling color profiles based on what the quickgamma homepage says about this:

https://quickgamma.de/indexen.html

To quote:

"[...]

Apple has been using the LUT since many years for its operating system built in color management. In fact, Apple has registered the private ICC Profile tag video card gamma table (vcgt) with the International Color Consortium (ICC). This tag is used in a dedicated Monitor Profile and holds the gamma values, which are then loaded into the LUT by a loader program.

Hardware based Monitor Calibration Systems also use the vcgt tag, which in this case contains the correction data to achieve the monitor calibration. Because Windows did not provide a LUT loader, each calibration program had to provide its own LUT loader program. ...

[...]

Things changed when Windows 7 came along and provided its built in calibration loader, which not only loads the LUT at system start up, but also takes care of Standby and Hibernate.

[...]"

As you might notice, the two stories from those pages seem to conflict?

Right now, when I use Windows to load my icc profile, I get correct colors. Same if I use the DisplayCAL profile loader.

However, if I start f.lux during the day (where f.lux shouldn't mess with the colors at all) I get semi-incorrect colors - they end up "more correct" than when I have no color profile loaded at all, but still VERY incorrect.


Surely you don't expect color profiles to work when f.lux is operating? I'm not sure what the point would be for color profiles when you're explicitly opting for distorted color reproduction with f.lux.

Is what you want more like "don't mess with the operation of color profiles when f.lux is disabled or otherwise shouldn't be adjusting the screen?"


>Surely you don't expect color profiles to work when f.lux is operating?

1. Don't call me Shirley.

2. I in fact do, in a way:

>I'm not sure what the point would be for color profiles when you're explicitly opting for distorted color reproduction with f.lux.

I opt for __linear distortion__ of a non-linear function. What f.lux ought to do consists of shifting the whitepoint coordinates of the current color profile. Which has the point of only distorting colors in a way where my brain can adapt to it.

But that's not exactly what f.lux does - it already DOES try to account for color profiles, but it does so incorrectly.


Hi herf, your software is really nice but one thing that kept me from using it (and adopted since Apple's 'night shift', though I don't use all days) is that I enjoy photography. Probably you heard this a few times, but one thing that I'd love to have is this off for photos (I'd switch from being an eventual user to being a full-time user).


I do color sensitive work now and then too. All you need to do is right-click the icon and select "disable while running [active program]".

I was very happy when I found f.lux. Finally something replacing my own tool I wrote for my Atari.

The main benefits with f.lux is you can easily set brightness and on/off with keys in any program or game, no need to navigate with mouse in menus.


You can just disable it for an hour. That's what I do at least.


Herf - it would be great if you guys could have an official position on this paper and to really help us understand what flux is doing or not doing. I tend to see you folks as the vanguard pushing the bigger tech companies to adopt your technology - I for one tell EVERYONE to download Flux.


Ever since f.lux came into my life, my long screen starring hours have stopped causing me headaches and bad sleep. My phone and my computer have night mode on, all the time! Thank you for f.lux!


I'd like to thank you as well. I jailbroke my iPhone just to get flux on there (before Night Shift), and still prefer it over Night Shift.


how does eye color factor into this? I read that objects with certain colors reflect rays of the same wavelength.


Thank you for many years of f.lux. How would you say it stacks up against Nightshift in iOS and macOS natively?


f.lux is amazing; thanks for your work!


I'm in the process of building a Philips Hue-compatible light therapy LED strip that goes above my bed, and I chose 500 nm cyan LEDs due to this concern. The goal is to have the lights gradually wake me up every morning and help align my sleep cycles, as I suffer from Delayed Phase Sleep Disorder.

Figure 3[0] in the paper seems to show that 500 nm is safe, and that melanopsin has high absorption at 500nm, which has important effects on circadian rhythm[1].

Anyone more knowledgable than me know if this setup is safe?

[0]: https://www.nature.com/articles/s41598-018-28254-8/figures/3 [1]: https://en.wikipedia.org/wiki/Melanopsin#Effects_on_circadia...


Yes, also if your eyes are closed when it starts, 500nm is better because more gets through the eyelid. Better if you diffuse more and spread out the light over more of the visual field.

But the main thing you'll want to make sure is that you can get enough light. There is some evidence that >200 lux with this wavelength will help, but most light therapy uses tons of light (1500 melanopic lux or more):

https://fluxometer.com/rainbow/#!id=Light%20Therapy/ReTimer


Thanks for the tips! That link is super interesting.

I'm guessing melanopic lux is the lux output weighted over the spectral absorption curve of your eyes?

Some napkin math: I have ten 3W LEDs, and each might produce around 1000 lux when fully driven. If we drive each at half strength, and half of the generated lux is melanopic lux, that's 2500 melanopic lux.


Yes, lux depends on the viewing distance. Lumens is related to total light in all directions, and lux is "per area" (i.e. gets smaller with 1/distance^2).

Melanopic is weighted by the non-visual response in the eye, and this number corresponds pretty closely to the spectrum that drives circadian effects, and likely, mood. So whereas an incandescent might be 0.45 melanopic lux per visual lux, a really blue sky (or a 500nm LED) is around 2.0 "M/P".


I'm sorry I can't help you, but after reading an article posted here about melatonin I got interested in light therapy, but commercial devices are a bit expensive. Are you documenting your project?


Sure, it's not the most exciting project, but I might do a short writeup when I'm done.

I originally purchased these nice LED strip bars with enclosure in blue[0], but after reading this site by the manufacturers of a commercial green therapy light[1], I was convinced to switch to turquoise/cyan.

Turquoise isn't that popular so I wasn't able to find any strips/bars, and I got these individual 3W bead LED modules instead.[2]

For the Hue integration, I'm using a Mesh Bee + UartSBee v5[3] with firmware from PeeVeeOne[4]. It outputs PWM, and I'm hooking it up to a cheapo constant current LED driver I got from Aliexpress. Since all the LEDs need to be in series for a constant current driver, I'm probably looking at a ~20V power supply to power the whole thing.

My bedframe has a headboard, so I'm planning on 3D printing some mounts that clamp on top.

[0]: https://www.ebay.com/itm/50CM-U-Aluminium-shell-DC-12V-36-SM...

[1]: http://www.sunnexbiotech.com/blue%20vs%20green%20light.html

[2]: https://www.aliexpress.com/item/10-pcs-3W-Turquoise-Cyan-LED...

[3a]: https://www.seeedstudio.com/Mesh-Bee-Open-Source-Zigbee-Pro-...

[3b]: https://www.seeedstudio.com/UartSBee-V5-p-1752.html

[4]: https://peeveeone.com/?page_id=252


So those cyan LED's have a forward voltage drop of 3.2-3.6 volts. So you'd be looking at a 32V-36V 350ma power supply or thereabouts to hook them up in series.

If it were me, I'd probably run everything in parallel just to keep the voltages lower, and be able to use readily available power adapters.

Aliexpress has a PWM controlled constant current driver that takes 5-35V in and outputs 350ma max [1]. 10 of them are $20, so they're not too expensive.

At a forward voltage of 3.3V for the LED's, you'd be looking at slightly more than 1W per LED at 350ma (P = VI).

Those constant current supplies probably have an efficiency of maybe 66%, taking that into consideration, I would think a 12V 2A power supply would be enough to drive the entire thing. And that could be a wall wart that you get at the local hardware store.

[1] https://www.aliexpress.com/store/product/10PCS-A58B-1W-LED-D...


Just tested with my power supply, and the minimum V_on seems to be about 2.7V. So if I want to drive all 10 in series, I'll need 30V+. If I had three banks in a 4,3,3 configuration, I could get away with a 12V power supply as well, which would be nice since I already have a bunch of 12V 5A wall warts.

I already got the board you linked, supposedly configured for 700 mA. Haven't tested yet. The datasheet for the part says it can go up to 2A[0], so I could potentially modify the feedback circuit for 1A, which would reach the full 3W rating of the LEDs.

One issue with that driver chip is that the PWM/enable is active low, so I think I may just stick an inverter on the output of the Mesh Bee. The SDK for the NXP part has changed since the ZLL repo was updated, and I haven't had much luck getting it to compile myself.

[0]: http://www.xlsemi.com/datasheet/XL4001%20datasheet.pdf


Why do you want to drive the 10 LEDs in series?


So note the I/V curve on the diode [3]. The minimum on at 2.7V is probably going to be the "knee" voltage. Sending 1A through the led will be a higher voltage.

The easiest way to test it is to get a multimeter, and put 1A through the led, then measure the voltage across the diode, and that will be the voltage you're targeting. (or you can just use one of the 700ma current regulators for a good estimate, placing the enable to ground.)

Also keep in mind that those current regulators are buck converters and they're not 100% efficient (no regulator is, really). So you're going to want to add 20-30% more power at a minimum on top of the load you're planning on driving with it.

And if you're going to drive 12V of LED's, expect to need 15-18V to drive the buck converter. That's because of the way buck converters work.

The feedback voltage on that chip is a fixed 1.2V and that's used as an internal voltage reference (I guess because they didn't add one into the chip).

They have a circuit diagram for that part, and it looks like CS and Rcs are the most important things on that sheet. CS is the "Current Sense" that measures the voltage across the current sense resistor (Rcs). They give the formula for Calculating Rcs to get to 1A (ILED = 0.155 / Rcs), and I get .15 ohm for Rcs at 1A.

Then you can either replace it with another sense resistor with something like this [2], or an appropriate length of copper wire [1] to give you the correct resistance.

As far as the PWM/enable inversion goes, just invert it in software. 100% full duty cycle would be off and 0% would be on. If you have a Raspberry PI laying around you can easily set one of the pins to PWM to test out your inverter code [4].

I'm going down a similar path to build a UV light box for exposing PCB's and the like.

Best of luck!

[1] http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.htm...

[2] https://www.mouser.com/ProductDetail/Bourns/CRM2512-FX-R150E...

[3] https://www.electronics-tutorials.ws/blog/i-v-characteristic...

[4] https://circuitdigest.com/microcontroller-projects/raspberry...


You're a hero; thank you for posting details.


I would be very interested to see a write up of what you are doing here as I have a similar problem. Any chance you could share one if you create one? Email in my profile.


Yep, will do!


Do you have a spectral output chart for those LEDs? You might be surprised how much blue is still in the output.


Yeah, especially with these cheapo Chinese LEDs. I looked into spectrometers, but they seem pretty pricey. Maybe some sort of plastic filter that blocks the shorter wavelengths?


How about a simple prism? That would tell you instantly if there's any blue light in the stream.

Edit: You might need a mask to create a slit of light so you can see the spectrum clearly.


Oh, yeah! Totally forgot about those from high school chemistry class. :)

I'm sure there'll be _some_ blue light. I don't know if a prism would be high resolution enough to tell if it's a dangerous level.


Yeah, you won't be able to see the intensity, but you will be able to see what components of the spectrum are there. It's also and easy way to test filters.


Any reason why you are not just buying a Philips wake up light? I have one and it's great. Especially during darker months


I wanted something that was compatible with my existing Hue system, and specifically targeted wavelengths for light therapy.

I already have a normal Hue bulb next to my bed on a schedule, similar to the wake up light, but a light strip right above my head seems more appealing to me.


How long have you been using yours? I have been using one for about 3 years. Initially it worked great, but it seems the light just doesn't do it anymore and the alarm sounds are what eventually wake me up.


About a year. But I am having similar experiences.


Perhaps try and cycle using the light. Couple months using it, one month off etc.


Got my kitchen lighting done with these hue controlled light strips. Not entirely certain if they fulfill your need, but maybe an alternative if someone wants to replicate. They have very good CRI, which might be good/bad for your application. https://www.sowilodesign.com


I remember having serious issues when I was younger with this. It's still sort of a a problem, but I've learned to cope. I'd also be interested if you documented your setup :).


Wow that's totally what I have too. I didn't think there was a name for it.

I mean the delayed phase sleep disorder. Will talk to the doc about it.


> To protect your eyes from blue light, Karunarathne advises to [...] avoid looking at your cell phones or tablets in the dark.

Can someone explain why it would be worse to look at a cell phone in the dark? It's emitting the same blue light (or less, if the display gets dimmer) as it is in a bright environment. Why is that light more harmful in a dark environment?


Because of the way your eyes work. If it is bright, your pupil will be shrunk, to not be blinded by the luminosity. When it is dark, your pupil will be opened wide up.

It is this principle that camera apertures are based on.

Now if you have your pupil wide open in a completely dark environment and put a 100% brightness screen at ~10cm of your eyes, what do you expect will happen ? Our eyes are made for nature, that means day and night, now we have technology that is akin to a handheld sun and you use this at night at 10cm of your face, our eyes are simply not equipped to handle this.


... but I don't put a 100% brightness screen in front of my eyes at night. Do people really do that? Don't they know how to adjust brightness?

Indoors, I use about 30% brightness. As the day gets dimmer, that slides down to about 25%. If I'm reading something in bed, I start at about 10% and as my eyes adapt, go down to 1%. When I'm finding it hard to keep my eyes open, I take that as my signal to go to sleep. Am I ridiculously unusual?


This isn't weird at all. I'm jealous of your 1%. The default low on my phone is maybe like 5-10% (I don't know how to check this), and it feels crazy bright when I'm in bed.


If you're on Android, I recommend Screen Filter[1] which will draw a semi transparent overlay on top of nearly everything (depending on the phone and/or OS version, it might not dim the status bar, bottom navigation buttons, lock screen, etc.). I use it a lot when reading at night, because the lowest brightness setting on my phone is also too bright for dark-adapted eyes.

[1] https://play.google.com/store/apps/details?id=com.haxor


Shades is also a good app on android for dimming the whole screen much darker than the default slider will go.


Wow, thanks a lot. Just tried it out and I'm loving it so far. I really appreciate the default reversion in case the slider is set too low, as well as the non-linear percentage slider allowing for fine-grained control at lower brightness values.


For iPhones you can set a full screen “zoom” with low light filter on. It’s under Settings -> General -> Accessibility -> Zoom. Set the filter to Low Light, then turn on zoom, then double tap with three fingers to zoom out all the way.


What phone are you using?


It can be beneficial to suppose a perfectly spherical cow.

You aren't unusual for trying to prevent your eyes from being harmed. If you were, an article which helps inform on the topic of eye care would not be popular.


I do for videos because I notice that I just see a lot more. Turning down the brightness is like turning down the light in the room that was filmed in. That's both on OLED and on LCD screens (wish I could go back to OLED, though, but it has gotten fairly rare among cheaper phones).


Some people do it, yes. My girlfriend used to have her phone at 100%. Personally I use f.lux and the lowest setting.


Interesting; when I got 2 new pair of eyeglasses last month, again I fell for the usual "buy all the coatings" spiel. I didn't much understand what they were, but I was told one causes refractions that bother some people.

I absolutely notice a blue refraction from car headlights when driving at night. I keep thinking I'm seeing a police light from somewhere. It's fine, just interesting. Well, after looking at a few lens coating websites, and realizing my lenses reflect blue light back at me if I have a light source to reflect, they're obviously blocking blue light -- cool!

I've never been much for f.lux style color shifting, I HATE the obviously inaccurate colors. I also wonder if we'll find that some of these technologies don't work nearly as well as a blue filter, and that perhaps the light just LOOKS less blue.

But I'm sure glad to have glasses that now block some blue light. Also, it validates my desire to keep the blinds open at work; I have LOTS of light coming into my cubicle area. Sometimes it's even a bit annoying but keeping my pupils small should help.


What makes f.lux inaccurate? Color perception is relative and if you are in a dark room, your eyes should adjust to different white points naturally. This is the same thing that makes it so a white piece of paper looks white no matter whether you are inside or outside, even though the actual light reflected from the paper has a radically different spectrum in each case.


shrug. Same way the 'average' person does. Looks totally wrong. I notice it from the first minute it starts to shift. I notice it every time I look at the display of a coworker who uses it. I tried it for a few months thinking it would cue me to go home, at least, but I just started snoozing it the instant it began sunsetting -- forget the more extreme ends of the progression.

I never work in a perfectly dark room. My office is next to a window, both at home, and at work. The lights are on. Plus, all of these things help keep my pupils small which apparently helps prevent the blue light harm to begin with.


The colors on a RGB-based display is incorrect either way (with flux or without flux) at any color temperature (cool, warm, or in between).

Why is it that you prefer the incorrect colors without flux to the incorrect colors with flux?

Sounds like you prefer cool color temperature which is no more correct than warm color temperature.


I'm not OP but I can't stand f.lux and its clones. I never adjust. The inaccurate colors stand out to me no matter what the conditions are.


"Inaccurate" is definitely an incorrect way to describe the colors. The colors are correct from relative colorimetric perspective, you're just changing the white point.


Any 3-color screen will never be true to life accurate. It's always a simulation of the real thing projected into the three dimensions of color that most of us perceive.

Colors appear to change dramatically under different lighting conditions, but we accept these changes as normal given context. Changing the white balance on your screen is no different. It's not inaccurate, it's just rendered as if in different lighting conditions.


Just because "white" can be recognized as "white" under varying color temperatures doesn't mean that the spectrum isn't truncated, and thus less accurate.

We have the ability to adapt to different color temperatures and perceive the relative output, but we're still missing information when shifted from the full spectrum daylight we evolved with.

Consider a recorded rock song: if we gradually apply a low pass filter of increasing strength, the high frequencies will be cut. We'll still be able to hear and recognize the cymbals, for example, but the stronger the filter, the less accurate the output.

Just because we can recognize relative colors under different lighting conditions, it doesn't mean that they're still accurate when we remove information.


> perhaps the light just LOOKS less blue.

That is a really interesting distinction! Blue is a color derived by social consensus, but it is also a particular wavelength of photons. I'm curious about what's there if we dive in and examine what specific wavelengths of light (numerically) cause damage, and what is the overlap with what we typically consider the color blue. I'm sure it's not one to one.


We're able to see similar colors under different lighting conditions only because the mind adjusts what you see for lighting. Seems like the same should be true for filters.


> I absolutely notice a blue refraction from car headlights when driving at night.

I think some ultra-bright headlights are actually slightly blue.


Especially with the move to LED headlights, car lights have gotten significantly "colder" in color temperature


nah, it's a refraction in the lens -- eg, i see it offset from the actual light source.


Isn't blue light important in the mornings for keeping the circadian rhythm aligned? I thought you were supposed to avoid it in the evenings only. Probably it'd be fine for you if you're getting a lot of light, but might be bad if you don't.


Hmm. If I've been in the dark for a while and then pick up my phone, the brightness hurts my eyes for a moment until they adjust to it. When I put the phone down, it takes a moment before I begin to be able to see things in the dark room. Doesn't that indicate that my pupils were initially dilated in the darkness and then constricted when I began looking at my bright phone?

I wonder how significant the difference is between pupil dilation while looking at a bright phone in a dark room and while looking at a bright phone in a bright room.


If it is the delay in dilation that causes the damage, I imagine it's exacerbated by constantly changing dilation as well. Ie, if I'm staring at my phone in the dark, I rarely keep focus on it. I often glance to the left or w/e, thus causing the screen to appear too bright again. Same for laptop-ing in the dark. I often find myself looking at keys, or thinking off in the distance, or w/e.


serious question: Why do people like to do work or leisure in pitch black rooms? Don't you feel clumsy, sleepy and uncomfortable when everything is dark? How can anybody go more than 10 minutes without needing to use vision to interact with their surrounding environment?

I personally can't have the lights off even if I'm watching a movie. Maybe because I was raised without TV, I can't sit still for more than 20 minutes watching entertainment before I feel the urge to do something productive like wasting time on the internet.


> serious question: Why do people like to do work or leisure in pitch black rooms?

I prefer low light, not pitch black. Generally speaking I want my monitor to be the main focus. Same for TV; if I care about the viewing experience I dim the lights. I might even prefer pitch black honestly, but due to the reasons being discussed, the contrast is just too great.

> Don't you feel clumsy, sleepy and uncomfortable when everything is dark?

Nope

> How can anybody go more than 10 minutes without needing to use vision to interact with their surrounding environment?

Not sure, tbh. I imagine it has to do with not wanting to interact with the environment most of the time. Ie, what am I going to do with my banister? It's just sitting there.. why do I need to interact with it? Most of my house is the same way. If I'm doing X, rarely do I need to interact with the rest of the house or room.

Does it bother you that there are things behind your head that you can't see?


Very personal answer to your serious question (sorry if it isn’t relevant for others): I can’t stand the stimulus caused by light (one of the problems that come with being part of the autistic spectrum). I wear sunglasses at work (because of the bright fluorescent lights above). Being able to work in the dark is a relief.


It's funny that I'm reading this thread because I just went through this exact same thing last night and it was weird. I don't ever make a habit of using my phone in the dark, but I did yesterday and I did at full brightness and for many hours and it did not feel good.

Eventually after like 6 hours in the dark and accidentally using just one eye for reading- eventually I started to see really trippy and weird visual noise in the dark areas of the room. I also noticed that if shone at the right angle- the pitch black areas of the room suddenly lit up, as though I was giving my over-exposed eye some kind of night vision, which is weird because you'd expect an oversaturated eye to be completely blind in the darkness.

Now this is all anecdotal, but reading screens in pitch black light has always felt bad for me. I don't understand people who insist on watching TV shows or movies in a fully pitch black room. I mean I get why school teachers and home theater enthusiasts do it- but for normal TV viewing, it just seems wrong to me.


>Doesn't that indicate that my pupils were initially dilated in the darkness and then constricted when I began looking at my bright phone?

Somewhat constricted. They're still more open that if they were in a fully lit environment, even more so in the sun.


get some IR leds and illuminate your face and take a selfie in the dark looking at your phone using the front camera.

The back camera usually has an IR blocking filter, but often the front camera does not. You can check by videoing an IR led (like from a remote control) with the front camera and seeing if you can pick up the flashing when you activate it.


The same happens with computer screens. Most offices are under-lit (or over-lit but only if ALL your UI has a dark background).

To get a feel for this, point your cell phone at your desk area and take a picture (without HDR enabled). If you can't take a picture without over– or under–exposing the screen or the wall, then your setup is putting strain on the eyes.


This is absolute quackery.

Your camera's cell phone barely manages to hold approximately eight stops of latitude. Blowing out that pathetic dynamic range has no grounding in relation to any notion of "eye strain".


> Your camera's cell phone barely manages to hold approximately eight stops of latitude

That's precisely what makes it a decent tool for detecting lighting imbalance. Just because our eyes mask the issue with high perceptual dynamic doesn't mean it's not straining them.


Eight. Stops. Is. Not. High.


That only happens for, what, less than a second before your eye adjusts? It's not like your eye knows it's day or night, and the pupil stays fixed.


My phone (unlike my PC, or a TV) is smart, and thus dynamically alters brightness based on ambient light. It's pretty cool and certainly mitigaets the above somewhat


At least on my phone (LG G5), the lowest brightness setting is still incredibly bright in an otherwise dark room. I use Twilight[0] to dim it further, though unfortunately Google changed Android so it can't affect the soft buttons. (Which is fine for almost all apps because the soft button bar is black, but of course Chrome changes it to white with no way to fix it.)

[0] https://twilight.urbandroid.org


I recommend, instead of Twilight, to use Lux[0]. It has many settings and lets you completely set your own brightness curve, with "negative" brightnesses that darken your screen with an overlay included. Also lets you adjust color temp, of course. The free version had all the features I needed.

[0] https://play.google.com/store/apps/details?id=com.vitocassis...


Thanks for prompting me to go back and check the settings on the Darker(https://play.google.com/store/apps/details?id=com.mlhg.scree...) looks like it now dims the soft navigation buttons


iOS is the same. Even on the warmest setting and lowest brightness it's still very bright. Unfortunately, there is no app to do anything about it like there is on Android.


There is a setting, so I can tap three times with three fingers each time top open a menu and set a filter, and I choose low light mode

It's not the easiest mode to find, but works.


You can configure iOS Home button triple-click to invert the screen, so it's white text on a black background. There is a "Smart Invert" option so that photos are not affected.


You can also apply an accessibility filter to increase the darkness in iOS. I have this mapped to a triple home-button click and use it all the time (after reading to kids etc)

https://www.techrepublic.com/article/pro-tip-dim-your-ios-sc...


I'm on X so no more Home button, but good suggestion. For last 9 months I had my phone on grayscale, which was nice, but still a bit high for my taste.


You can go further by reducing white point in accessibility settings. The colour filters there also go beyond night shift.


Interesting. I was on grayscale for last couple of months, but didn't know I can reduce the white point also. Will try.


My TV, a Toshiba Regza, has dynamic brightness. It works very well as my primary monitor.


Would using a kindle at night have the same effect? It's light is kind of yellowish (I think)


Probably less so because it's reflected off the e-ink screen surface and probably diffused a bit that way.


Right. Also the illumination is at the bottom of the screen and hence indirect, whihc might reduce it further.


My first gen Paperwhite is most definitely blue, it's obvious at low brightness. Don't know about later models.


I'm not a doctor but in a dark environment your pupils would be less constricted.

From what i heard this is also why sunglasses that don't block UV light are worse than not having sunglasses at all.


Your pupils are more dilated, due to the surrounding darkness, and hence let more light in. If you were to dim your screen enough to compensate, it would likely be too dark to read.


Your pupils are dilated; you're receiving more light.


For the f.lux Mac users here, do you prefer that to Mac's Night Shift?

I just found this article, which details why f.lux is better than Night Shift. But it's written by f.lux, so it's a bit biased.

https://9to5mac.com/2017/03/28/flux-developer-says-apples-ne...

I'm guessing both are better than nothing, but is one actually better than the other?


I've been using F.lux for over seven years. Advantages…

- You have a great deal of control over the blue level. Night Shift's blue level is higher than F.lux's default, and not adjustable.

- Flux transitions more naturally as the sun goes down.

- More scheduling options, "disable until tomorrow".

- the big one: disabling per-app or for full-screen apps. You probably don't want Flux on while watching a movie or binging on a videogame. (I set up my lady friend with Night Shift and watched a movie with her recently, spent the whole film wondering why they made such awful color choices)


First point is incorrect. Night Shift's color temperature is adjustable, which includes the blue level.


While the color temperature is adjustable, I've found (anecdotally) that the warmest setting on Night shift is still quite a bit more blue compared to the max warmness on F.lux.

(Tested on iMac and MacBook Air, may be different for other screens)


- Night Shift is disabled for external displays. That's another killer one.


NightShift absolutely works on external displays


I use Night Shift on my external 4K LG monitor no problem.


I prefer f.lux, with the exception of fullscreen video, specifically YouTube on Chrome, where certain colors "break through" the filtering and appear bright white. Not sure how it works, but it's the only thing Night Shift seems to do better. If f.lux fixed it I'd be back in a heartbeat


I use Night Shift. I'm able to fall asleep minutes after closing my laptop and laying down. For me it's more about comfort than sleep. The blue light is much too bright late at night. My computer no longer hurts my eyes when I stay up late working on cool things.


I use Night Shift because it’s built in and does what I want it to do without glitching.


I don't quite understand. Blue light - any blue light - causes blindness? So we shouldn't look at the sky even?

I've never heard blue being a danger other than its effect on the biological clock, so that seems like a pretty bold claim. Ultraviolet, sure...

Though buried in there is something about immune system and vitamin E levels...

I really find it hard to believe that blue light exposure is automatically bad. We have receptors for that specific purpose. Wearing blue light filtering sunglasses all the time as the article suggestions seems a bit ridiculous. Why give up one color entirely?


The first thing to realize about any scientific paper is that it's wrong. To a very good approximation all scientific papers are wrong, until the results are replicated a couple of dozen times and failed to be replicated a few times this could well be an artifact of the methods they used.

Never make life changed based on the results of one single study.


It says that your body's normal antioxidants prevent damage. This is only a problem for people who have low levels of alpha tocopherol, e.g. from malnourishment or aging.


We have chemical receptors on our tongue and in our nose for poisons. We have neurons that detect pain. Just because we can sense it doesn't mean it's not harmful.


But those receptors signal something unpleasant - a terrible taste, pain. Looking at blue doesn't cause pain or unpleasantness.


I'd guess that the negative effects of blue light over a lifetime might only have become noticeable in modern times, with better vision correction and treatment for conditions like glaucoma and cataracts. If so, there probably hasn't been significant evolutionary pressure to dislike viewing blue light. Also, half of outdoors is blue half the time, so instinctual blue-avoidance would probably hurt survival.

But it is perhaps misleading to concentrate on things that are exclusively blue... The real problem is light containing the relevant range of frequencies, which includes many non-blue colors, due to the relative presence of other frequencies. For example, your eyes would probably absorb much fewer relevant photons when staring at an empty patch of sky than when staring at the sun, even though the sun is not considered blue. And looking at the sun does cause unpleasantness.


On the contrary in fact, I find gazing at the blue sky to be calming and enjoyable, and find it promotes diffuse thinking, which can greatly speed up problem solving.


It's not about merely seeing something blue, like the sky, in a generally warm temperature ambient light. It's about blue color from screens.


Some people like the smell of ozone.

Ozone doesn't have a smell. What you actually smell is your nose burning. Ozone is a very aggressive oxidizer.

Looking directly at the sun is also a super bad idea.


> Ozone doesn't have a smell. What you actually smell is your nose burning. Ozone is a very aggressive oxidizer.

Wait, what? Do you have a source for this?


> Ozone doesn't have a smell.

This does not sound right. This is what I see on Wikipedia which is also exactly what I was taught in high school:

> It is a pale blue gas with a distinctively pungent smell.

Source: https://en.wikipedia.org/wiki/Ozone


I don't think your argument holds. Case in point: it is possible to make poison tasty.


Try gazing unprotected at a nearby arc welder flash.


Just speculating here, but I‘d say since eyes have evolved to also look at the sky, I’d say no. Shining a laser on cells is different from sunlight in various ways. First, laser light waves are coherent (perfectly overlapping), so their effect might amplify A LOT. The dosage (J/cm) used by the researchers also might be 100x as high as the sun‘s, for all we know. Then, there’s the thing that sunlight is a mixture of a very broad range of frequencies, from far infrared (and below, microwaves etc) up to ultraviolet (and beyond, eg X-rays, which luckily don’t arrive at the earth surface in huge doses). Again, just speculating, but near infrared has been found to have a beneficial effect on retinal diseases, so maybe it compensates for the problems blue light creates.


"since eyes have evolved to also look at the sky"

On the other hand the Inuit had to invent snow goggles to prevent blindness caused by the bright sun reflected off the white snow-covered terrain. Like, actual eye damage blindness. That's been attributed to UV but perhaps blue wavelengths play a role as well.


As others mentioned:

When you look at the sky during a bright day your pupils are narrow and let little portion of the light through. When you look at blue light in the dark - they are dilated and let more light through.


>I really find it hard to believe that blue light exposure is automatically bad.

Few things are "automatically" bad. Over time though, effects are cummulative, and there are also breaking points for lots of bad stuff.


In addition to f.lux, I also use the Dark Reader Chrome extension[1], which dynamically generates dark themes for every page you visit. It seems to make a bigger difference than using f.lux.

1. https://chrome.google.com/webstore/detail/dark-reader/eimadp...


How does the amount of blue light we see from our computers and mobile devices compare to the blue light seen from the rest of the world quantitatively? While I agree that f.lux helps in the night, I'd guess that the impact caused by f.lux to prevent the effect mentioned in the article is pretty minimal. (Obviously, I have no citations or references; just a wild guess.)


Thanks for sharing! I did not know about this. I use Stylus and dark themes for many sites, but this will be great for random sites. https://add0n.com/stylus.html


Def'ly a great relief for my eye strain - using it during the day too and keeping on by default. One annoyance is that Chrome needs to let the address bar be darkened as well as it stands out like a neon tube when Dark Reader is on.


I just use a dark chrome theme with it to get around that issue.


Using this on an OLED screen really makes it clear that the current standard of light backgrounds and dark text is only optimal with backlit LCD panels.


"to wear sunglasses that can filter both UV and blue light"

But isn't this bad with other consequences? I thought the lack of blue/violet light was the cause of myopia? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5233810/


You can't develop myopia or hyperopia after your eyes/skull/orbital muscles are done growing. So this suggestion probably applies only to adults.

Keep in mind that this is age-related macular degeneration. Your photoreceptor cells are protected by the α-tocopherol until "a person's 50s or 60s." You wouldn't need any prophylactic interventions until then.


Interesting. My myopia worsened a bit from ages 22-27 or so. Does that mean my skull and muscles were changing still?


Actually yes. Doctors have told me that I should wait til 25 to see If I am candidate to eye laser operation because that is the average age where people stop developing his muscle eyes.


>You can't develop myopia or hyperopia after your eyes/skull/orbital muscles are done growing. Do you have a source for that?

Would the inverse also be true?


I don't know about a source—a medical textbook? Those conditions are explicitly caused by the eye being squished out of the "proper" shape for focusing light by the way the skull and extraocular muscles end up developing.

I suppose you could develop myopia later in life as a result of inflammation of the extraocular muscles (orbital myositis), but this would be 1. temporary, and 2. not treated as its own disease, but rather as a symptom.


VSP basically owns TechShield Blue. Other manufacturers have competing products but they are all pretty horrible.

The cynic in me wonders if the researchers have any ties to VSP.


I was recently diagnosed with a condition called retinitis pigmentosa (it basically just destroys your retinas). It's part of a larger condition called usher syndrome (which caused my severe hearing loss at birth). I'm on heavy doses of vitamin a palmitate as well as some other vitamins. Another thing that I haven't done yet but will be doing shortly is blue light blocking glasses, especially since I sit in front of a computer all day. I also use f.lux and night shift on windows and mac respectively. I'm 22 and have lost a significant portion of my night and peripheral vision so I'm still just trying to figure this all out. Any tips are welcome.


I'm in my late 30s and was recently diagnosed with retinitis pigmentosa too. I've started to use night shift/f.lux on my computers, and reading this article is also motivating me to update my glasses to one with blue light blocking.


My wife's brother has retinitis pigmentosa. He's 64 and has been blind for years. You definitely have my sympathies.

I don't have any advice except to learn Braille, which I'm sure is not very encouraging. I hope a cure is found soon.


I use f.lux all day I don't know if I'm particularly sensitive or if it's all in my head but when I turn off f.lux, especially at night, to watch some movie or video I can physically feel my pupils dilate and it almost feels like my eyes go from being at rest to being strained.


As a linux user, I have found that Redshift works better than f.lux. It's the first thing that I install on a new machine of mine.


Last year use default "Night Light" in GNOME. Very easy and can be enabled in one click like Wifi or BT.


Same - I have flux setup to be active during work hours (at work) and evening hours (at home) so it's filtering blue light on all my devices. When I accidentally close it or turn it off for a movie, I feel like a vampire in sunlight. I have such an easier time falling asleep thanks to flux.


I use something similar to flux for my lightbulbs, and I've noticed the same thing when I disable it at night. My eyes are definitely strained.


Care to link what you're using? It would be nice to modify my room to use changing color spectrum bulbs depending on the time of day.


I'm using this [0] Home Assistant component. I also use a similar component to slowly turn my lights on in the morning instead of an alarm clock, which works really well.

[0] https://www.home-assistant.io/components/switch.flux/


Before using f.lux fulltime I noticed that I sometimes got headaches after long days in front of displays, so I started using f.lux not only after sundown, but also during the day and it's very effective. There's no way I'm going back. Essential piece of software for me.


I am excited about LED lights for their efficiency, but keep seeing articles like this and don't understand the practical ramifications, like "what bulbs should I buy?"

I messaged Cree on Twitter, expecting a very corporate response, but they linked to some studies (which I haven't yet had time to explore.) FWIW - https://www.energy.gov/eere/ssl/street-lighting-blue-light-a... and https://www.lrc.rpi.edu/resources/newsroom/pr_story.asp?id=3... were the resources they suggested.


The message is: there is no more risk from LED than older sources, by the metrics we have now.

I would suggest that one problem is that LEDs don't "warm dim" (unless you get some special ones from Philips and a few others), and people tend to dim them less overall.


What do you mean by "warm dim"?


An incandescent/halogen will go to warmer temperatures when dimmed. So it might start at 2800-3000K but be 2100-2200K at 1% brightness.


Perhaps you could look into buying red lampshades. The direct illumination of the LED would still be rather blue but the light passing through the shade would not.


"The researcher found that a molecule called alpha tocoferol, a Vitamin E derivative and a natural antioxidant in the eye and body, stops the cells from dying. However, as a person ages or the immune system is suppressed, people lose the ability to fight against the attack by retinal and blue light."

Does this mean that consuming alpha tocoferol can combat the toxic effect of blue light? If so, at what dosage?


Note that the lens of the eye yellows as you get older which significantly reduces the amount of blue light that reaches the retina. So much so that there is an idea floating around that older people don't get enough blue light to properly make the circadian stuff work and that teenagers get too much.


One solution I use is a 1/8" thick sheet of amber transparent rigid plastic/acrylic. It is designed to cut UV, but it also cuts blue light. I bought a 2'x4' sheet from an online site (since ads are probably not permitted, I will not mention the name of the company), and they cut it to size specifications for me. Out of that I got filters for my 14", 15" and 17" laptops, and a 30" LED TV.

I find it easier on my eyes at night (both laptop and TV), and it has its place since the TV can't run f.lux and redshift.


Recommendations of products are fine. Paid promotions or kickbacks are frowned on though.


I wear computer glasses at all times when working, and highly recommend them. It greatly reduces eye strain, and filters blue light.

If anyone is looking for a good pair, I buy mine from Gunnar [0] (no affiliation).

[0] https://gunnar.com/


Tried these and some Uvex glasses that block 100% of blue light (Gunnars are very low % blocking relatively). Zero impact on my strain. I have seen many others state the same. It's obv there are many causes for strain, just wish I could figure mine out.


what about EagleEyes? Does anybody have experience with these?

Blue light blocking: https://www.eagleeyes.com/pages/blue-light-blocking

Computer sunglasses https://www.eagleeyes.com/pages/digital-eye-protection


if you need prescription versions, you can get them at LensCrafters: https://www.lenscrafters.com/lc-us/blueiq-lenses

I use those and they work wonders.


Many of the comments here are about displays, but what about the LEDs sold as replacement for incandescent and halogen bulbs?


I think, white LED bulbs do use a single wavelength blue LED, but they pass it through phosphors which transform it into a similar distribution of wavelength that you would find from an incandescent bulb, or sunlight. LED's are a lot better than fluorescent lighting, which does often have very dramatic peaks and gaps.

In theory, you can look at the CRI rating, but in fact CRI only uses a small number of wavelength probes for the test, so a rating of 100 doesn't necessarily mean a smooth spectrum, it could be the manufacturer has tuned wavelength peaks in order to game the test. There are better rating systems being developed, but they're not used by manufacturers or mandated by governments yet.

I actually think it might be the lightbulbs that change colour which could be problematic. I wouldn't be suprised if some of those did generate the colour just with single wavelength blue, green and red sources. Hopefully the better ones would have individual phosphors for each r/g/b source which produces a spectrum which when combined is reasonable.

I would be particularly careful about cheap/unbranded colour-variable lightbulbs. I doubt they've been through much or any consumer testing, it seems you can buy anything straight off the boat from China through domestic web stores these days.


Yes, white LEDs are based on blue LEDs with phosphors. But I don't think they convert all the blue light, so they're still heavy on the blue output. I'd need to see a reference to believe they have less peakiness in the spectrum than fluorescent lights.

CRI may not be the best rating for spectrum smoothness, but it's the only one we have for now. It's still hard to find bulbs that even bother to rate themselves.


Check the spec sheet of the bulbs, specifically the color temperature in kelvin. Ignore the "warm white" and similar marketing terms, they are too fuzzy.

A LED with low color temperature and high CRI should have pretty much the same spectrum as incandescent. If you want really low temperatures look for some retro filament style LED lights.

https://en.wikipedia.org/wiki/Color_temperature#Categorizing...


It's tricky, though, since most LED bulbs use a single wavelength of blue LEDs which get downshifted by phosphors, even in high CRI bulbs, you can have an unnaturally large spike in the blue (often around 450nm).


CRI unfortunately is not a good test, it still can produce very high ratings even when the spectrum is spiky.


95+CRI is an indicator for mostly lack of spikes. Look at Yuji (yujiintl.com), they seem to be the only ones selling actual high-CRI LEDs with sane pricing (i.e., no ideological markup).


I'd like to try one of these out, but at $20 per bulb it's a a bit steep. Are you able to comment how they compare to the Feit Electric 90+ CRI bulbs sold at Costco for a few dollars a bulb?


For many of us whose use of these blue-light emitting computer and phone screens is necessary, what can we do about it?


Use f.lux or an equivalent (most OS have their own implementation by now) that filters out the blue light at software/rendering level, it's not perfect but you do instantly feel the comfort it brings to your eyes. Been using f.lux for over 10 years and it also helps alot with going to sleep at night. When it's off your eyes/brain thinks that they are in daytime / broad daylight, when it's on I fall asleep 2 or 3 times faster than without.


The biggest problem I have with it is that everything looks so much worse that I just wind up turning it off all the time.

Is this so seriously a threat to vision that it's worth it? I don't have the sleeping issues with screens some people seem to report, so I wasn't really willing to commit to it over that.


> The biggest problem I have with it is that everything looks so much worse that I just wind up turning it off all the time.

Change the settings. What you should do is take a sheet of paper and put it next to your screen. Then match your screen's white to the sheet. It's only a bit less blue. There's no need to set everything dark orange.


Okay, but that's a trade-off, you're still getting a fair amount of blue light through in that case. How much less blue light do you want? What's optimal for minimizing eye damage if that's a significant risk?


You don't want to eliminate all blue from your life. Decreasing it is good enough. What's the point of making your computer screen red if the minute you step outside in the sun you lose any benefit?


Make sure you change it to the "Slow: Natural Timing" transition speed so the shift is gradual. The faster speeds (which I believe are default) are jarring and too easy to notice.


Also Alt + page up/down to adjust brightness without affecting colorshift.


The benefit of software such as f.lux and Gnome Nightlight is that they turn themselves on at night and off in the morning. It seems like the OP wants to remove blue light at all times, in which case should be handled through your monitor settings. A software solution would be unnecessary.


You can wear glasses that filter blue light.

The article mentions wearing them outside, but they work inside as well.

I wear them, and they provide other benefits for me as well (https://news.ycombinator.com/item?id=16529054#16531413)


So I used to have glasses with a blue blocker filter on them - I absolutely hated every second of wearing them. Literally everything appeared yellow through them - my screens, sheets of paper, even snow looked like it had been peed on - awful. I mean, it's certainly not surprising - they did block blue light after all. But I wore them for 3 months and then marched back to the optician to have them replaced with normal lenses. And the optician has promised that the effect would be very subtle and hardly noticeable in daily use - well, maybe I'm particularly sensitive to it, but the effect was very noticeable to me.


My new eyeglasses have a coating that reflect blue light. They absolutely do NOT shift the color spectrum. You can't tell the coating is there. Perhaps it's newer or different tech. Look into it.


Are you talking about the coating opticians are pushing for "computer glasses" now in the US?

I have that, and while it is subtle, I definitely can tell it is there. It doesn't ruin general color perception, unlike many obviously yellow/brown lenses. But, it definitely alters the world to have a slight yellow tinge, a bit like you can get from the haze caused by a distant dust storm or wild fire.

It doesn't bother me, but I am aware of it. I actually prefer brown sunglasses and photochromatics because what is marketed as "gray" often looks sickly purple to me.


I just don't understand how that could possibly work - it doesn't matter if the glasses absorb or reflect blue light - as long as it doesn't reach your eyes, anything that is normally white will look yellow, as you're not seeing the blue component. You can't filter/reflect blue light and still see it.


Colour perception is not that simple. The visual cortex compensates. It's the same sort of compensation that means that you see the same colours for objects under artificial lighting and in sunlight, even though spectral analysis will show them not to be.


Yup. I don't know how else to explain it. Trust me, I'm very sensitive to color temperature changes. I have 4 pair of eyeglasses I rotate through every day. Only 2 of them have the latest anti-blue coating. You simply cannot see it. I don't know what product it is, but a good example description from Zeiss:

https://www.zeiss.com/vision-care/en_us/products/coating-col...


Judging by the relative light intensities of daylight and computer screen light, I would say it will be sufficient to close your eyes for 6 minutes when you are outside on a sunny day to offset 10 hours of computer use.

Maybe dark adaptation can change that, but I haven't found anything about that upon quick unprofessional examination of [0].

[0]: http://twin.sci-hub.tw/6979/4112e16f7195f7f33cd3e861c6345df0...


I've been wondering if GB-R LED backlit displays help? I haven't seen any reviews which compare the LED spectrum vs a standard white (blue)LED backlit display, but it might be something of interest.

Examples of a GB-R LED backlit display include the NEC PA302W, so they aren't common.


Well at least a start is to use software like f.lux that reduces the blue levels on the screen. There are also over screen filters and yellow tinted glasses that can filter the blue light.


It sounds like one should use it permanently, and not just at night. But the real problem is the spectral composition of the synthetic white light on screens. Now I want fluorescent backlights back.


Is there any reason to think that narrowband blue is worse than broadband blue? It makes for poor CRI when used as a light source but if the display blue is near the peak sensitivity frequency for blue it should result in slightly less total power being delivered to the eye than an equivalent blackbody spectrum white light.


Maybe total power isn't what matters and peak sensitivity is also where peak damage is.


Android has a blue light filter, I haven't turned it off yet.


I turned it on recently, mostly just to experiment and see how annoying the difference would be. It was subtle enough that I just left the filter on.

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