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Ooh the post author! I have a question. When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship? I bu

Ooh the post author! I have a question. When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship? I buy dim bulbs that have a temperature of 2700K for evening applications precisely because of this belief that brightness and color impacts sleep quality, am I right or is it just placebo? It seems to help...

Waterluvian 4y ago
I think the temperature is describing, in a way, the dominant wavelength (think the peak of a normal-ish curve on the EM spectrum). A lightbulb that appears less blue will inevitably be emitting less blue. But that’s not to say it isn’t emitting across a broad swath of the spectrum and you’re still getting the wavelengths that are being argued as problematic to sleep. You’d need more data or tools to determine just how much of the “offending” wavelengths are making it into your peepers. Anyways, hopefully a real expert chimes in. :)
alwayslikethis 4y ago
Temperature describes a distribution of wavelengths. Higher is bluer, lower is yellower. Both brightness and color matters. If you want to be as safe as possible, buy pure red LEDs for use 1-2 hours before bed and don't expose yourself to any non-red light. The difference is (no pun intended) night and day.
lightedman 4y ago
"When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship?" Hi! LED and LASER module design and manufacturing tech here! There is a small correlation with LEDs and luminous flux - the ones with higher green peaks (2700K-~4000K CCT) will have a higher luminous flux at full power as green (~552nm) is where the lumen is weighted and those tend to have more output in that converted color range versus the cool white (which have a little less green and a bit more blue.) This really only applies to phosphor-converted LEDs, RGB combo LEDs are narrow-spectrum in emission, and you can't really describe them by luminous flux, rather photon flux or radiant flux per output channel, as the luminous flux will always be highest from the green LED, no matter what, due to the weighting of the lumen in the green wavelengths.

Waterluvian 4y ago

I think the temperature is describing, in a way, the dominant wavelength (think the peak of a normal-ish curve on the EM spectrum). A lightbulb that appears less blue will inevitably be emitting less blue. But that’s not to say it isn’t emitting across a broad swath of the spectrum and you’re still getting the wavelengths that are being argued as problematic to sleep. You’d need more data or tools to determine just how much of the “offending” wavelengths are making it into your peepers. Anyways, hopefully a real expert chimes in. :)

alwayslikethis 4y ago

Temperature describes a distribution of wavelengths. Higher is bluer, lower is yellower. Both brightness and color matters. If you want to be as safe as possible, buy pure red LEDs for use 1-2 hours before bed and don't expose yourself to any non-red light. The difference is (no pun intended) night and day.

lightedman 4y ago

"When I buy light bulbs they always list the color temperature but not the lumineous flux, what's the relationship?" Hi! LED and LASER module design and manufacturing tech here! There is a small correlation with LEDs and luminous flux - the ones with higher green peaks (2700K-~4000K CCT) will have a higher luminous flux at full power as green (~552nm) is where the lumen is weighted and those tend to have more output in that converted color range versus the cool white (which have a little less green and a bit more blue.) This really only applies to phosphor-converted LEDs, RGB combo LEDs are narrow-spectrum in emission, and you can't really describe them by luminous flux, rather photon flux or radiant flux per output channel, as the luminous flux will always be highest from the green LED, no matter what, due to the weighting of the lumen in the green wavelengths.