Found it: https://news.ycombinator.com/item?id=12575725 https://news.ycombinator.com/item?id=12575725 Note: the top rated post has focused on editorial quality

Found it: https://news.ycombinator.com/item?id=12575725 https://news.ycombinator.com/item?id=12575725 Note: the top rated post has focused on editorial quality and glossed over the fact that it is narrow band light and cannot be compared as equivalently in wide spectrum terms beyond perception (e.g colour temperature), this is pointed out in the 2nd immediate child by sandworm101. I should point out that the properties of the light beyond perception _are_ important due to ipRGCs: the mammalian retina contains ipRGC photo-receptors that do not relay images to the brain but are responsible for various reflexive responses. These receptors are sensitive to a wide spectrum of light peeking around blue [1]. Ultimately these ipRGCs release melanopsin which is known to affect circadian rhythm, and is thought to control sleep wake patterns [2]. I expect you've heard about this vaugley before as I have, but what is interesting in the context of LEDs is that ipRGCs appear to respond to more of a continuum of spectrum, so unlike our cones they would be "perceiving" LED light quite differently to our consciously perceived images. [1] https://en.wikipedia.org/wiki/Melanopsin#Function https://en.wikipedia.org/wiki/Melanopsin#Function [2] https://en.wikipedia.org/wiki/Melanopsin#Control_of_sleep/wake_patterns https://en.wikipedia.org/wiki/Melanopsin#Control_of_sleep/wa...