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Comment by _nkoa | Hacker News Reader

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.

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... 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?

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.

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.

What phone are you using?

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.

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.

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.

> 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.

> 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.

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.

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.

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.

>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.

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.

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

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.

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.

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.

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 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...

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.

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...

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)

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

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.

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