Hacker News

herf said a year ago:

f.lux author here. I'm pasting parts of the 458 page PDF into Google Translate.

The recommendations look very good, and don't particularly match the Yahoo article.

1. They recommend IEEE 1789 as a flicker standard for Europe, which is fantastic, as it covers lower levels of stroboscopic flicker that other standards have missed. (e.g., typical 120Hz flicker from direct-wire TLEDs)

2. They re-state the "acute" hazard from extremely bright LEDs, while urging some caution on "chronic exposure" to lower light levels. Suggest that some automotive lights could be a problem since they have high luminance. Urge more research on progression of macular degeneration and chronic exposure. The question about acute levels refers to a paper by Hunter [2012]. Nobody is saying that screens or residential lights pose a new problem.

3. Circadian recommendations are solid - more light during the day, and reduce light around 480nm at night. Pregnant women and children may have lower thresholds.

4. Say most ophthalmic lenses filtering blue light don't do very much, and specialized ones (you'd say very orange or red) are required for circadian effects.

thinkling said a year ago:

> "Nobody is saying that screens or residential lights pose a new problem."

This right here is the key for most people.

Thanks for f.lux, by the way, have been running it for years!

eecsninja said a year ago:

I had a travel plug adapter (for conversion between US/UK/EU-style) that had a bright blue LED on it to indicate power.

I don't know who thought the choice of blue was a good idea, because as a travel adapter, it would be plugged into the hotel room where the user would be sleeping. /facepalm

I ended up taping a piece of paper over the LED.

justasitsounds said a year ago:

I came here to grumble about exactly this

(edit: 'I')

hnick said a year ago:

When I changed ISPs I also changed my modem, which is in the closet in our master bedroom. It's brighter than a disco so I bought some light dimmer stickers. It's still too bright so once I remember where I put them, I'm going to add another layer. It's ridiculous. The only upside is that they are green instead of blue, thankfully.

Nition said a year ago:

The Asus RT-AC1900 router (and probably others) has a button on the back to turn all the LEDs on or off. Would be nice if everything had that. I'm sure it's caused some customer confusion at some point but it resets to the lights being on when it's rebooted.

waste_monk said a year ago:

My router (an Archer, can't recall the model) has a "night mode" configurable where the LEDs are disabled during a given time range.

I haven't bothered to turn it on since it lives in the hallway, but at least the option is available.

glennericksen said a year ago:

Thanks for sharing this. I checked my router config and found the option to turn off LED lights except power. A more elegant solution than electrical tape I had been using before.

buckminster said a year ago:

Modern TVs often have an on-screen menu option to turn off annoying LEDs.

knodi123 said a year ago:

interestingly, the human eye is most sensitive to green light, in the sense of perceived-brightness-per-lumen.

londons_explore said a year ago:

Notably, while green LED's exist, we haven't yet managed to make an efficient green LED.

If we had, then illuminating streets etc. with green LED's would save a lot of electricity for the same perceived brightness.

eveningcoffee said a year ago:

It is good then that we have not. Green light is the most ugliest kind in my opinion.

hnick said a year ago:

I didn't know that! Maybe that's why it's so annoying. My reference to blue was the common belief (fact?) that blue light messes with wakefulness hormones and isn't a good idea around bedtime (hence f.lux).

londons_explore said a year ago:

A lumen is already a measure of perceived brightness.

You can have a 10 watt UV light, but you can't have a 10 lumen UV light for example.

knodi123 said a year ago:

oops, I meant radiant flux instead of lumens.

simcop2387 said a year ago:

Black car touch up paint is what I usually use. Either that or nail polish.

jaggederest said a year ago:

It's hard to go wrong with electrical tape. I haven't found an LED that could shine through it yet.

copperx said a year ago:

Electrical tape was useless on my ASUS router with its blinding blue LEDs. Three layers didn't even get rid of the problem, because the lights are so bright that they shine through the white plastic casing of the router. It's incredibly annoying. I finally placed the router inside a cereal box.

waiseristy said a year ago:

Electrical tape turns to goop after a few months(years), black duct tape lasts slightly longer

justinclift said a year ago:

Same here. Black electrical tape. Also useful on laptop/monitor/tablet/phone webcams and mics. :)

sarego said a year ago:

I just installed f.lux. It is almost midnight here. As soon as it installed and my screen tuned almost yellow I can immediately feel the strain on my eyes disappear and replaced with a coolness. This is incredible software. I will probably use this the rest of my life.Thank you!

copperx said a year ago:

I hope f.lux becomes irrelevant once dark mode becomes the standard in all devices. If the web catches on and if our screens become OLED (or use any technology where dark pixels aren't illuminated), then "night mode" will be seen as a crazy hack.

WorldMaker said a year ago:

"Night mode" is still useful with Dark Mode. In most applications Dark Mode still uses plenty blues and greens for accent colors and often strong whites for text colors. Even if fewer overall pixels are dedicated to those colors, it's still useful to color shift them away from blue in the evenings.

Tempest1981 said a year ago:

How do you like viewing maps in dark mode? I tried Apple's Maps app on macOS, and it felt weird -- like navigating at night. Otherwise, dark mode seems good.

chrisfinne said a year ago:

f.lux changed my life.

Always thought I was just a night person. After decades of late-night coding, f.lux educated me about blue light and allowed me to rejoin the living.

equalunique said a year ago:

>4. Say most ophthalmic lenses filtering blue light don't do very much, and specialized ones (you'd say very orange or red) are required for circadian effects.

I have had years of success averting personal blue-light issues using what probably falls into the "specialized" lenses category: Uvex S1933X glasses. They came in a 3-pack on Amazon for around $25. The pairs are next to my bed, on my desk, and in my backpack. Inexpensive enough to where I won't loose sleep over breaking a pair. Good not just for device screens, but also for the annoying bright blue power buttons/indicators on just about every other peripheral.

mleonhard said a year ago:

I just wish the Uvex glasses were more comfortable.

sigi45 said a year ago:

Do you have by any chance a proper spectrometer? After all you developed f.lux?

Would you be able to share images on what the real difference is with and without f.lux? And also the ophthalmic lenses? I just got some so i'm quite curious :)

blencdr said a year ago:

Thank you ! f.lux is a blessing, i use it since a few years and if it happens to use a computer on the evening without it I feel assaulted with agressive blue light.

pcdoodle said a year ago:

Respect. Love your software.

vbuwivbiu said a year ago:

another thankyou for f.lux here!

DoctorOW said a year ago:

> The report distinguished between acute exposure of high-intensity LED light, and "chronic exposure" to lower intensity sources.

I can't say I'm convinced that LEDs are a hazard. This study doesn't really say anything new. Cooler/brighter lights are more similar to daylight. Staring into the sun is bad for you, emulating sunlight at night keeps you up.

> ANSES recommended buying "warm white" LED lighting

This line shows LEDs aren't even really the hazard. It's akin to saying a substance was found that prevents cancer and the article saying that its sunscreen.

Jolter said a year ago:

> This study doesn't really say anything new.

Nitpick: This is a report from a regulatory body. It is not a clinical study. Rather, I would expect that they have read a number of studies, and collated the results into this report.

Meaning, it is not meant to introduce new facts, it is meant to introduce a new recommendation and explain the basis for it.

DoctorOW said a year ago:

My critique was of the article itself. The article seems likely to mislead people into thinking new findings show LEDs are inherently harmful to eyesight, when the study seems to actually communicate the importance of factoring brightness and color temperature into the decision. Sure, one can get the right idea from reading the article thoroughly and critically but if you read the comments on the article it's clear the target audience is being misled.

ricardobeat said a year ago:

You’re making assumptions based on a lack of content this article did not set out to provide.

There is more to it than color temperature, the frequencies emitted by LEDs can be vastly different even if the light appears the same color. Here’s an article from last year specifically about blue light and retinal damage: https://www.forbes.com/sites/fionamcmillan/2018/08/11/how-bl...

CuriousSkeptic said a year ago:

Warm white refers to some particular average. But how do you find led’s that don’t hide a spike of blue light in that average? Most places where I run into led-lights don’t advertise the spectral distribution.

hoytech said a year ago:

This is a really fun and easy experiment you might like:


marak830 said a year ago:

Oh that's awesome! I have a colleague writing a semester on science projects for kids, this is definitely going to fit in with that!

scotty79 said a year ago:
Someone1234 said a year ago:

I was skeptical, but great link. I might order one to play with. I didn't even realize that was a thing.

peatmoss said a year ago:

My understanding is that LEDs have a very specific, peaky distribution. Heating a wire results in a wide distribution of color temps, but solid state lighting is a really narrow band of color.

I have a photo panel that needs two separate color LEDs to produce a balanced feeling color temp.

_ph_ said a year ago:

As I wrote (https://news.ycombinator.com/item?id=19919819) LEDs usually have a single color: blue. However the resulting spectrum generated by the phosphor can have almost any shape, some high-quality LEDs even have a pretty perfect black body spectrum without a blue line. Of course they are more expensive and also less efficient.

danharaj said a year ago:

> some high-quality LEDs

Where can I get these?

jarvist said a year ago:

In terms of commercially available bulbs, the 'Philips Master LED ExpertColor' (all in spotlight 'GU10' etc. format) have an extremely high quality halogen-like spectrum.

_ph_ said a year ago:

Search for "high CRI LEDs". This should turn up LED module vendors which usually have the data sheets which should include a LED spectrum. The warmer the LED temperature is, the smaller the blue peak. For example here: https://www.led1.de/shop/files/Datenblaetter/Osram-OS/Oslon/... or here https://lumstatic.com/9p/Vt/uRNvyjbnQnfzzgO6rg.pdf.

Paianni said a year ago:


_ph_ said a year ago:

I really hope, someone makes a cheap spectrometer as a smartphone accessory. That would be the best way to quickly assess the properties of light sources. Beyond the health impact, one wants to know the light spectrum when e.g. selecting lamps for fish tanks or plant lighting.

As a very coarse but easily available poor-mans spectrometer, I have been taking pictures of a greycard with my camera in raw-mode. Looking at the histogram balanced for a fixed color temperature, e.g. sunlight, for the r,g,b-channels gives very different results depending on different light sources. While you don't see a true spectrum, just the strength of the blue vs. the green and red channel usually is very revealing.

gtrubetskoy said a year ago:

Any compact disk works as a spectrometer.


NIL8 said a year ago:

I've never seen this. Thanks!

scotty79 said a year ago:

It's cheap and works without the smartphone


_ph_ said a year ago:

Yes, that is a good start - I would like to have curve with the relative strengths of the spectrum. But maybe it is enough to carefully calibrate the smartphone camera on the diffraction sprectra to generate a course graph.

Also, if no diffraction grating is at hand, a random audio CD usually is up to the task :)

janekm said a year ago:

That only shows differences in white balance and tone. It can't give you any information about the CRI since you only have 3 channels of colour sensors in your camera. If you use a colour swatch palette that would be different.

_ph_ said a year ago:

Yes, of course. It doesn't give you a "spectrum" at all. Only a very rough guesstimate on how the colors are balanced. But good enough to see, whether there is a large blue peak (blue line much stronger than red and green) or not. Just using your camera and a rgb histogram.

But using a color palette is a great idea. With some calibration work, this could give a rough spectral curve with a single picture. I need to investigate this :). One would require to get a palette, where the colors are generated not by rgb pigment mixing but by absorbing/reflecting distinct wavelengths. Of course, the MacBeth color targets would fufil that condition, now how to get a wavelength calibration from this? Have to read up on things...

janekm said a year ago:

Another option would be to use colour correction gels like from Rosco. They publish transmission curves for their gels: https://emea.rosco.com/en/products/filters/r3220-double-blue... (click on the little i). You could take pictures of the light source through a set of different gels and reverse to an approximation of the spectrum of the light source.

Interestingly they are also now offering gels to correct the colour casts of LED lighting: https://emea.rosco.com/en/product/opti-flecs

There are samples swatches of their gels, which can be had by either asking a theatrical lighting supply company or on eBay.

oasisbob said a year ago:

CRI is a common metric for LED lighting. I'm not intimately familiar with the standard, but would expect a large spectral aberration to negatively impact the CRI.

When I was building up some high-CRI architectural fixtures, finding fully characterized LEDs wasn't much of an issue. At the consumer level it can be tough to get good details beyond color temperature.

jwr said a year ago:

I am designing my own lighting and I found the same thing. There is a huge discrepancy between what you can get at the source from manufacturers and what ends up in "consumer" hands. Most of what is sold in the stores is poorly-specified crap, built to be as cheap as possible.

mindslight said a year ago:

Just guessing from what I know about LEDs and efficiency, I suspect they all just hide a spike of the same blue light in that average.

m463 said a year ago:

What's interesting is that a Phd biology researcher I know had been researching LED lighting and wound healing.

Things like children with severe burns exposed to certain wavelengths of light - control would be one limb vs another limb, exposed one showed improved healing.

I believe the wavelength was I believe 660nm or 670nm.

Florin_Andrei said a year ago:

> Staring into the sun is bad for you

Due to intensity, not due to spectrum.

tzs said a year ago:

One thing I never see mentioned when it comes to blue light and its effect on circadian rhythms is whether it is the absolute level of blue light that matters, or the relative amount compared to other concurrent light, or the relative amount compared to some earlier time such as the peak blue level over the last day.

It is relevant for figuring out strategies to avoid having blue light mess with your sleep. If it is an absolute level, then you either need to keep light sources low enough at night so that they can't have a blue component that is too high, or you need to find out the spectrum of the light and figure out the maximum level you can set the source to so that the blue won't be too high.

If it is just the relative amount compared to concurrent light, then as long as you use lights that have an acceptable spectrum you should be able set these as bright as you want without messing up your sleep.

If it is relative to something like the peak for the day, then there is a possibility that instead of turning down blue at night you could turn it up during the day to raise that peak to give you more blue leeway at night.

DtnB said a year ago:

I actually looked into this recently and found some articles(which I have since lost) that explained that it would appear that the delta between blue light in the morning and at night is the mechanism by which our circadian rhythm seems to work.

However, working with the idea that blue light is photo toxic, it is most likely better to reduce your blue light at night rather than increase it in the morning.

I wanted to do this experiment with dosing myself with blue light in the morning but I abandoned that after seeing research on photo toxicity

Perhaps establishing a morning habit of going and standing in front of an east facing window might be a worthy experiment?

sizzle said a year ago:

Just looked up blue light photo toxicity, that is some scary stuff! So is staring at blue light computer monitors all day causing corneal cell death?

How much is this increasing the risk of macular degeneration?

rangibaby said a year ago:

> Just looked up blue light photo toxicity, that is some scary stuff! So is staring at blue light computer monitors all day causing corneal cell death?

I think you're going to be OK. There is a very large, strong (stronger than any monitor) source of blue light that your eyes can handle at least 12 hours of exposure per day to

DtnB said a year ago:

While you are right to ward off this person's paranoia and we really shouldn't be completely freaking out about light exposure from our phones and such.

I think you are minimizing the issue. We wear sunglasses when it is bright (and should as it can be harmful to our eyes), we don't stare directly at the sun, we don't have it anywhere near as close to our faces, and we don't have the sunlight at night which adds another 2-4 hours of exposure to blue light.

There would appear to be more intense blue light in an LED than coming from the sun. This page while not a particularly good primary source has some comparisons of the intensity of the blue light in LEDs vs sunlight. https://iristech.co/pwm-flicker/

"The use of blue light is becoming increasingly prominent in our society, and a large segment of the world population is now subjected to daily exposure (from a few minutes to several hours) of artificial light at an unusual time of the day (night). Because light has a cumulative effect and many different characteristics (e.g., wavelength, intensity, duration of the exposure, time of day), it is important to consider the spectral output of the light source to minimize the danger that may be associated with blue light exposure. Thus, LEDs with an emission peak of around 470–480 nm should be preferred to LEDs that have an emission peak below 450 nm. Although we are convinced that exposure to blue light from LEDs in the range 470–480 nm for a short to medium period (days to a few weeks) should not significantly increase the risk of development of ocular pathologies, this conclusion cannot be generalized to a long-term exposure (months to years). Finally, we believe that additional studies on the safety of long-term exposure to low levels of blue light are needed to determine the effects of blue light on the eye."


Basically, we shouldn't go out of our way to expose ourselves to excess blue light if we can help it. We don't know what it does entirely. Its not worth losing your mind over either but its not quite simple as 'the sun is blue. you'll be fine'

tzs said a year ago:

> There would appear to be more intense blue light in an LED than coming from the sun.

I was surprised at how intense LEDs are. When I got my eclipse viewing glasses [1] for viewing the 2017-08-21 eclipse I spent some time trying them out on every seemingly bright light source around my house and my office.

The only things that were easily visible through the eclipse glasses were a 3500 lumen 200 watt halogen bulb, and the white LEDs from an iPhone 6 plus flashlight app, a hand cranked emergency flashlight, and an LED head lamp.

[1] https://www.amazon.com/gp/product/B007MD8E0Q/

mrmondo said a year ago:

LED lighting panels in our office is so bad it looks as if there is a constant haze or fog in the office.

A number of people in the office were complaining of visual fatigue and a hazing effecting especially after working 3+ hours, additionally multiple people had noted that colours seemed diluted or ‘dulled’.

The light spectrum seems to be missing parts of the visible light spectrum, to test this I acquired and installed high CRI lights and the area in inch I installed them lead to people satin to that they felt less sleep, more alert and more comfortable - of course these are all subjective results.

Subjective TLDR; LED lighting isn’t inherently bad IMO, but bad LED lighting is bad.

timcederman said a year ago:

Some of the issues (including the visual hazing) could be exacerbated by poor indoor air quality.

clarry said a year ago:

Glad to know it can be solved by installing a light.

TazeTSchnitzel said a year ago:

It sounds like your LED lighting might have a poor colour rendering index? It's a measure of how accurately colours can be perceived under particular light. The best — well, the reference — light source is the sun.

(I only know about this concept from Technology Connections's videos on high-pressure sodium lights.)

mrmondo said a year ago:

Yes it does, I ordered 4x high CRI LED bulbs from https://www.yujiintl.com/high-cri-led-lighting.html, I placed them around my teams working pod in cheap $10 desk lamps and they work a treat, very noticeable difference in our pod / cubical to the rest of the office.

_ph_ said a year ago:

Most (but not all) white LEDs have a specific property: the LED itself is creating pure blue light. To create the appeareance of white light, a part of the blue light is then converted to wavelengths in the green-red region via a phosphor coating. But, especially in cheaper configurations, it still leaves a pronounced blue emission line shaping the spectrum like this:

    0    00000
    0 00000000000
With some coatings, the blue line completely vanishes, creating a light distribution close to an incandescent lamp, but others have a very pronounced line. In the light (sorry) of the report, it sounds reasonable to require a certain minimum "spectrum quality" for lightbulbs beyond a certain power output.
mopsi said a year ago:

How does this look like to you?


Taken from Philips A60 leaflet.

_ph_ said a year ago:

This looks like a very good spectrum - pretty much like the best "warm" LEDs you can get. The blue peak is almost gone - or you can discuss whether it has a peak or a small weakness in the green-blue area.

seanalltogether said a year ago:

Is there a way to know which bulbs have this. Can you use CRI rating or something as a clue?

_ph_ said a year ago:

The CRI rating should be a good start. The lower the color temperature of the LED is, the less of a blue peak you should have. But the best would be to have a proper spectrum.

davidy123 said a year ago:

Regardless of the ultimate veracity of this (health guidance is …), there's still a benefit. So many shops have switched to selling "LED lighting," without distinguishing the quality. So there is a lot of harsh lighting being sold, that lasts a long time, which is a shame because colour temperature really does have a big effect. I was subjected to this in a lighting shop, where I was requesting fixtures that took a standard bulb, so I could plug in my own LED bulbs with controllable colour temperature, but the salesperson just couldn't see how that was better than their integrated LED systems.

ajuc said a year ago:

I don't know about the damage to eyes, but I can confirm problem with not getting "sleepy feeling" while using a computer late at night.

And the solutions for me was a software that gradually changes the color scheme of the operating system to be more red and less blue.

I'm using it since almost a year and it significantly helped with going to sleep earlier. I simply get sleepy at 22-23, even when doing stuff on a computer. Before installing the software I could sit for hours and notice it's already 02:00 and I'm not sleepy, just tired.

blunte said a year ago:

Anecdotal, but I love "daylight" white (which often looks quite blue to people at first). I spent a year of home office working with fantastic bright 6500K LED lighting, plus great big monitors calibrated.

At the end of a year of far too many hours worked (staring into screens), I was having strange vision problems and periods where my eyes actually felt pressurized and uncomfortable in their sockets.

When my insane project was over and I took some time off, my eye problems went away.

It's a shame if 6500K light is harmful, because I find it so energizing and refreshing compared to eye-burning yellow light.

This article said in passing that they cast doubts as to the efficacy of blue blocking glasses, but I don't see why proper filters on glasses wouldn't be effective.

seanalltogether said a year ago:

The article specifically calls out LED filament bulbs, but those bulbs aren't designed to actually output blue light to the user, they output the light that the phosphor coating on top should output, which is usually yellowish at 2800K. Are they talking specifically about LED bulbs and displays that still use separate RGB LEDs?

Itsdijital said a year ago:

Warm white LEDs still have about 30% of the blue light emission that cool white LEDs have. I really think the article is talking about cool white primarily though.

ricardobeat said a year ago:

AFAIK that’s always the case - a “white” LED is simply a blue diode + phosphor. They can still output a lot more blue light than an incandescent lamp, even when the resulting color temperature appears to be the same.

samsolomon said a year ago:

Interesting that the color of the light appears to be the issue here. When researching LED bulbs I read a ton of complaints about the flickering causing people headaches. It's hasn't caused me any issues though.

If you're curious about the flicker, it's visible by filming an LED bulb at 1/8 speed. I posted some videos here a while back.


Tempest1981 said a year ago:

Certain cars have taillights that flicker like crazy. What percentage of people are sensitive to this? The car makers don't seem to care.

AngryData said a year ago:

After buying LEDs by diode type online, instead of just whatever generic shit they sell at the hardware store for light fixtures, it really became apparent how trash most hardware store lights were. Not to mention many of the replacement LED socket lights are flickering from the mains frequency. The efficiency in random socket versions are crap compared to the high efficiency diodes you can buy if you look in the right places, often the store versions are around 60-100 lumens per watt, when you can get closer to 180-200 lumens per watt.

ourlordcaffeine said a year ago:

Can you give any pointers? I'm finding it quite hard to find datasheets and spectral measurements for bulbs sold online, they really don't give consumers much information.

butteroverflow said a year ago:

I know of a very good resource [0], although it is in Russian. But I think you can still make use of the comparison table [1]. Here are the rough translations of the columns:

    * brand;
    * model;
    * description;
    * price (RUB, divide it by 65 to get USD);
    * power in watts;
    * luminous flux in lumen;
    * efficiency (lumen / watt);
    * power of an equivalent incandescent lamp;
    * color temperature, K;
    * CRI;
    * light cone angle in degrees;
    * flicker coefficient;
    * supports switches with indicator lights;
    * overall rating (from 1 through 5, with 1 being lowest);
    * warranty in months;
    * can you still find it for sale?
There are lots of information on each lamp if you click on the model name.

[0] http://lamptest.ru

[1] http://lamptest.ru/results/

6DM said a year ago:

Does this mean we can finally outlaw blue headlights? (Note: I am joking, but I wish it were true.)

workingpatrick said a year ago:

AFAIK, most of the actually 'blue' headlights are not street legal. A Product of cheap aftermarket "HID Kits" or cheap XENON bulbs. Also, at least in Texas, basically any modification to your OEM headlights is verboten.

hnick said a year ago:

Are they actually 'blue'? I ask because of your quotes.

I heard before that we perceive slightly yellow light as white (because of the sun) and these 'blue' lights are really pure white but our perception shifts it.

Tempest1981 said a year ago:

They have a color temperature of 6500k (or 8000k? or higher?), which is a very blue tint of white.

Causality1 said a year ago:

A lot of their claims are unscientific.

>Teenagers' lenses aren't fully crystallized so blue light is more prone to disrupt their sleep patterns

benbojangles said a year ago:

Blue Spectrum light could be a big factor towards many health problems in the upper northern hemisphere (And probably lower southern), depression, macular retinopathy, migranes, tinnitus, affected autonomic function, CTE, post concussion syndrome - all affected by blue light, winter sun, white/blue LEDS, Car headlamps.

CuriousSkeptic said a year ago:

I would be interested to read more about this. Do you have some sources for those claims one could read?

hollander said a year ago:

I hate the bright white-blue headlights. They stand out so much, it's annoying to see them. Luckily I have a pair of Polaroid yellow night clipons. They do excellent work in the car in the evening, and many times during daytime as well.

rohan1024 said a year ago:

Why do you say that it will only affect particular regions? Do you mean people around equator are not that much affected by blue light?

benbojangles said a year ago:

I'm referring to the higher levels of blue spectrum light in the outer hemisphere compared to more red spectrum nearer to equatorial

leoedin said a year ago:

The sun is more blue spectrum than any LED. The only way the northern hemisphere would have problems with too much blue light (compared to the equator) is if it was in midsummer, when there's a lot of daylight.

Whatever blue light our LEDs produce indoors in winter is a fraction of that produced by the sun.

maxnoe said a year ago:

Not as much exposed due to more natural light

gppk said a year ago:

Little unsure how this is new findings:

> "exposure to an intense and powerful [LED] light is 'photo-toxic' and can lead to irreversible loss of retinal cells and diminished sharpness of vision,"

This is the reason we have light and laser safety standards to ensure that people aren't being exposed to dangerous levels of light...

jwr said a year ago:

I've been working on designing my lighting system for home. I find these reports annoying: without specifics, it's really just FUD. I am looking at datasheets for various LEDs, comparing CRIs and spectral distributions and I know already that my lights are going to be as "warm white" as possible (e.g. close to 2700K with a mix of higher-K added only during daytime) with the blue peak being as small as possible.

Incidentally, I actually DO want to add blue at times, because at my latitude days are short and dark during winter time and daylight temperature lighting seems to be beneficial during daytime hours.

How do I make use of "information" in this article? Do I reject LEDs altogether? Do I look to minimize certain frequencies? If so, which ones specifically? Do I avoid exceeding certain intensity? (then give me at threshold for Lux at eye position) Or do I avoid exceeding certain energy radiated within a specific band?

It's frustrating, because apart from the FUD, there is little to go on.

Itsdijital said a year ago:

Its the blue light, when I worked with "hard" blue LEDs (~460nm), I had to wear special glasses or I could literally feel my retinas melting.

Just stick with warm white and you'll be good. Warm white still emits a fair amount of blue light, but its approximately around 1/3 that of cool or daylight white LEDs.

Remember that natural sunlight is many orders of magnitude stronger than any 5000K LED and unlike LEDs has tons of UV as well. You could likely offset any damage and then some just by wearing sunglasses anytime you are out in the sun.

hevi_jos said a year ago:

Are you sure of that?

I believe humans have evolved to accept certain damage as natural and it just repairs itself.

When I expose myself to moderate amounts of light, my body reacts making my skin darker, which protects my skin against light.

Think for example gravity, that is exerting acceleration that damages our bodies, so our body has to react making bones and muscles. If we go to space and do not apply damage, the human becomes weaker, as it atrophies.

If we make a person to breathe in a total clean environment(filtered air), the immune system atrophies, then if you make the person breath normal air, you can kill her.

Of course we also know that too much is very bad, because it exceeds the limits of the human body to repair and something breaks down.

Common sense is key. If you go to the mountain or the sea in summer in Spain, Italy, Greece, Morroco, New Zealand... you should be extremely careful. This exposure in thousands of times more than indoors(or countries like UK) and UV light skyrockets.

9HZZRfNlpR said a year ago:

Same here, I live in a dark country. I use cold white where I work and warm white where I sleep, eat, watch tv. Basically evening time.

fouronnes3 said a year ago:

maybe my esp8266 2500 lumens led strip alarm clock wasn't such a good idea :O

derefr said a year ago:

How “intense and powerful” are we talking? Does this mean that 30mins daily exposure to an LED-based [10000lm] light-therapy lamp is a bad idea (compared to a non-LED-based light-therapy lamp)?

rconti said a year ago:

Unrelated, because IR is on the other side of the visible spectrum from blue light, but I'm convinced some day we'll find that IR is damaging to the eye. Every time I see those creepy glowing green eyes coming from the baby's room on friends' and relatives' baby monitors, I just shudder. I can't see blasting an infant with invisible light for no good reason.

lolc said a year ago:

Does infrared photography[0] creep you out too?

[0] https://en.wikipedia.org/wiki/Infrared_photography

anonuser123456 said a year ago:

The sun emits IR.

rconti said a year ago:

... and blue light?

said a year ago:
UI_at_80x24 said a year ago:

AC driven vs DC driven.

The 'quality' of light that is supplied from a DC power source is superior to that from a rectified AC source.

Cheap rectifiers are the scourge and cancer of this lighting tech. While not discounting the affect of the blue light + phosphor even 'cheap' LED's provide a better light output when DC driven.

Note: I can see/sense LED flicker (florescent tubes [or ballasts] nearing their end-of-life, and CFL's too.) So I am very sensitive to it. I also LOVE super-bright high kelvin 'cool/cold' 6500K+ lights in my home. My wife complains that it's like being in an operating room.

I wonder how much of the blue-light dislike/distrust is based on a biological leaning towards a preference to carbon-rich fire/flame orange-hue's.

i.e. a campfire or candle vs incandescent light vs halogen vs florescent vs LEDs on a scale of like to hate.

kitsunesoba said a year ago:

Blue/white fluorescent or LED lights drive me crazy in a home setting. If I could replace the one in my apartment’s kitchen I would. Their brightness is fine but their coldness keeps me on edge somehow.

UI_at_80x24 said a year ago:

It really is interesting how light affects us like that. I suffer from a congenital cornea disease and am slowly going blind until I get a transplant. I've often wondered if that's how/why I like the lights the way I do. They always feel "cheery" to me. It brightens my mood.

stordoff said a year ago:

> I also LOVE super-bright high kelvin 'cool/cold' 6500K+ lights in my home. My wife complains that it's like being in an operating room.

I love colour-changing bulbs for this. 5000K+ during the day, ~2800K at night.

korm said a year ago:

From my research and experience the operating room effect is largely due to bad color rendering with most (cheap) LEDs.

Good artwork/video/photo lighting with LEDs is very expensive and bought from specialized shops or the manufacturer, but it's the closest I've found to true sunlight.

If you'd like recommendations I like the Yugi strips.

cbwalker said a year ago:

Praise our caring European governments for banning incandescent light bulbs for the benefit of Philips and Osram while you can still burn as many liters of Diesel (together with noise pollution) as you please.