Hacker News Reader

Comment by derekp7 | Hacker News Reader

This article is about the effects of eye strain, not the overall mental health of looking at content on a screen.

With that in mind, what is it about a screen (emitted light) that is worse than outdoors reflect light? One item I can think of, is that looking at something with reflected natural light, the iris contracts based on the total amount of light hitting it. Whereas a screen may be brighter than the ambient light in the room, causing more of a point source of light to hit the retinas that would normally happen (which is why I've always found it more comfortable to watch TV with some other light on in the room vs. the room in total darkness).

View on HN

Screens are optimized for energy efficiency, so their emissions are restricted to a narrow range of visible frequencies. They don’t even really cover the whole range of colors, but mix them by combining RGB, which isn’t the real thing. Eg you can make something looking like violet light by mixing blue and red, but it’s not the same thing as the „real“ violet.

Sunlight, however, is a wild mix of broadband EM emissions across basically the whole spectrum, as you‘d expect from a glowing ball of plasma (halogen bulbs are actually similar in that regard, they need and do have a UV filter). About a third of the sun’s emitted energy hits the earth’s surface as near infrared light, and then there is UV etc.

Near infrared light is very beneficial, the mitochondria in our cells can increase their energy output as a direct consequence of receiving photons in that frequency range. There are lots of studies that showed improvement of many health conditions following near infrared or red light therapy. I wouldn’t be surprised if NIR light helped prevent myopia too.

As far as your visual system is concerned, "real" violet (e.g., from a tunable laser) and the "fake" RGB violet are pretty much the same--it's coded as the relative amounts of red/green or blue/yellow almost immediately after the cones.

Not necessarily. There is a lot of analog in the eyes beyond the nerves, and we don't know all the effects of ambient light on the entire eye structure. Even if the neural impulses end up being similar (and I doubt that) the eye as a whole organ may not respond the same way. Maybe that heat energy triggers something in the cornea? We don't know.

I don't disagree that UV and IR exposure may be important. Variations in UV exposure are thought to account for changing rates of myopia, for example. There may be non-image-forming receptors with different spectral sensitivities for circadian rhythms.

However, the structure and function of circuits involved in color representations has been studied to death, and it overwhelmingly points to a tristimulus model where the activation of the S/M/L cones matters, rather than the complete power spectrum of the illuminant. The sensitivity of rods and cones has measured measured with exquisite sensitivity, both behaviorally and by directly recording their electrical activity. Many downstream neurons in visual cortex get their input from individual L/M cones (parvocellular pathway). The others (magno, konio) have a fairly simple mix of inputs from a simple, spatially organized combination of the cones. In some cases (especially within the retina), the individual fibers have been traced and mapped.

There is a hell of a lot we don't know about the brain, but the very early representation of color isn't one of them. If you've got sources saying otherwise, I'd love to see them.

(This may come off a bit harsher than I meant. It's just that I'm surprised to hear someone doubt what I thought was a well-established principle with lots of data behind it. If you do have anything suggesting otherwise, I'd legitimately love to read it.

If not, WebVision is an excellent resource with a long chapter about color. https://webvision.med.utah.edu/book/part-vii-color-vision/co...

The Visual Neurosciences is a behemoth too, if you can find a copy; I don't think it's online.

We also can’t prove the absence the magical wardrobe with an entrance to Narnia from our universe, yet many people would say you are insane if you think it’s true.

would it help to set your screens to a grayscale setting?

It appears that the lack of violet light contributes to myopia[1]. There is abundant violet light outdoors.

[1] https://www.nature.com/articles/s41598-017-09388-7

My optometrist mentioned that one big problem with being in front of a screen is that the focal depth is close and constant, and that can cause headaches and other issues. She recommended I stare out a window or make a conscious effort to look into the distance for 10 minutes every hour.

This is what I've always heard as well. Your eye muscles end up "fixed" in a small range of positions, whereas with looking at stuff off-screen (and especially outdoors) your eye muscles do a wider variety of movements.

i dont know whether this is accurate, but i've found lighter color schemes for coding muuuch more pleasing on my eyes than extremely dark/contrast-y ones

Me too, I can't stand "dark themes". I also prefer a well lit room while some people prefer working in a dark room in front of a bright display.

Reply on news.ycombinator.com