* Light levels matter a lot, and we are trying to move the discussion to objective (and impartial) measures rather than talking about colors and subjective impressions
* Yes, our surveys of viewing distance (5000 people) were done in imperial, so we describe it that way for an English-speaking audience
* Yes, metamers are real - two spectra can stimulate the cones identically but be different to the non-visual system. We are comparing screens with identical luminance and 2-degree observer chromaticity matches, and the melanopic response does in fact vary
* The SCN has a logarithmic dose-response to light, so indeed 20% isn't that much. But 2x is an important change to talk about
* Our goals do not include making screens redder, but to improve outcomes for most people. We think the way to do this is by improving the contrast between day and night, and that this means that many of the the lights in the world should use timers that people can adjust based on the outcome they want
* The biggest surprise here (and the impetus for the article) is "wow that's more than double" when you first measure the phone, because the iPhone X doesn't feel that much bigger than an older phone
* Defaults certainly matter, especially when a product implies it will improve your sleep
Since many here uses desktops I wanted to share a small tip, but first an anecdotal observation: I got my first computer at age 10-11 back in the 80s (a VIC20) and we only had a 50Hz (Europe) interlaced 21" TV as a "monitor" at that time. After using it a few months even my teacher pointed out I was getting dark circles under my eyes. My sleep was getting worst. Many years later and years in front of computer screens I also found that I had gotten delayed sleep-phase syndrome as well - this at a time CRTs was the norm. For those who say that this light is not enough to affect sleep, I would say you're wrong. But that's anecdotal..
As to the tip: here is what I did - in your color management settings, create a ICC profile which turns off almost all blue and most green. This will leave you with a darker orange color which is perfect if you need to sit late and work. This also affect all programs on your screen. You can also use tools to create ICC profiles that inverts bright colors etc.
Now you can simply toggle between your normal ICC and the dark/orange one.
Also we know that pre-teens are more than twice as sensitive to light as people in their late teens [1], and CRTs were 9300K also [2], though they were quite a bit dimmer than current ones.
* Light levels matter a lot, and we are trying to move the discussion to objective (and impartial) measures rather than talking about colors and subjective impressions
* Yes, our surveys of viewing distance (5000 people) were done in imperial, so we describe it that way for an English-speaking audience
* Yes, metamers are real - two spectra can stimulate the cones identically but be different to the non-visual system. We are comparing screens with identical luminance and 2-degree observer chromaticity matches, and the melanopic response does in fact vary
* The SCN has a logarithmic dose-response to light, so indeed 20% isn't that much. But 2x is an important change to talk about
* Our goals do not include making screens redder, but to improve outcomes for most people. We think the way to do this is by improving the contrast between day and night, and that this means that many of the the lights in the world should use timers that people can adjust based on the outcome they want
* The biggest surprise here (and the impetus for the article) is "wow that's more than double" when you first measure the phone, because the iPhone X doesn't feel that much bigger than an older phone
* Defaults certainly matter, especially when a product implies it will improve your sleep