Should you avoid blue light before bed?
economist.com
economist.com
What you want is to accommodate both. Which has been a subject of recent academic literature concerning industry standards.
Specifically, there are new proposed metrics that accommodates brightness, but weighted in terms of its melatonin suppressing effects.
See the ref at the end.
Because you can have luminaries that are meaningfully bright physiologically speaking but dim to your perception of light or vice versa.
Your perception of “brightness” and also your perception of warmth (ie bright cool = day; warm dim = night) are not reliable heuristics.
Because your perception of light is calibrated in a manner that was adaptive to the species. It’s not a spectrometer. Moreover ipRGCs (intrinsically photosensitive retinal ganglion cells) have a different brightness weight that is distinct from what you perceive as bright light.
See the included document for an example.
But do note, it’s a work in progress, so I can’t say it’ll always be page 4 or whatever it happens to be.
Also, there my focus has been on comparing the emission of different luminaries irrespective of magnitude. But once you know the Mel-DEI, the brightness magnitude is just the product of that and the bulbs lux. Or so I’m inclined to say off the top of my head… This can be a surprisingly complicated topic, everything I know, has been from my own exploration. Whatever I say now, I could have very different opinions a year from now.
If I was more organized with regard to my academic literature reading list, I’d cite that but I’m not sure what happened to that list.
But the one thing I’d say I did very well: beautiful illustration if I dare say.
But I digress…
Here’s the link:
https://colbyn.github.io/lighting-misc-v1/main.pdf
(I’ve been working on it on / off for some time. It’s very much a rough draft at this time. Moreover its function is really to serve as a visual aid when talking to folks. So it’s very light on the commentary.)
Your eyes are broadly sensitive to the visible light spectrum.
But this is not uniformly distributed.
Emission in the green - yellow band is bright, equivalent intensity at higher energy wavelengths such as the 450nm emission pump of most LEDs can be quite dim.
It makes me wonder, IR is invisible, yet it can be very intense. Because you can’t perceive it, your eyes can’t adjust… Just as you can fry your reta with invisible light, what about ordinary LEDs that have a sharp spike at the 450nm region?
Could your eyes be slightly overexposed because it’s physically brighter than your perception?
I believe some damage does occur. But the eyes can heal. Blue light toxicity is a thing. But I think the threshold is based on irreversible damage… But I sometimes wonder if it’s too generous in favor of LED manufacturers.