Blue light in color-changing LEDs

November 10, 2024 10:32 AM

I have some color-changing smart LEDs that I have set to about 2700 Kelvins, approximately the same as a traditional incandescent bulb. Despite the warm setting, are they emitting more problematic blue light than the equivalent incandescent bulb? If I'm concerned about reducing blue light exposure for the sake of straightening out my screwed up sleep, am I worried about these?
posted by HotToddy to Health & Fitness (4 answers total)

2700K is a spectrum unit, so if the bulb claims 2700K then it should emit a spectrum very close to a black body radiator at 2700 kelvin, which most incandescent bulbs are.

There's a lot of technical details about how white (or simulated white) LEDs work, and the spectrum might be "dirty," but for the sake of your question, if it says 2700K, then you don't need to worry about significant excess blue because if there was excess blue, it wouldn't be rated 2700K.
posted by seanmpuckett at 11:42 AM on November 10 [2 favorites]

If this is an RGB bulb, it will be using some blue in the mix for 2700K. Mostly red and green, making yellow, but then some blue to make it not fully saturated yellow.

(I'm not a color professional, but in common use, color temperature means the perceived color matches the black body, rather than being a spectral match. And you will find RGB bulbs sold as doing 2700K.)
posted by away for regrooving at 2:33 PM on November 10 [1 favorite]

Response by poster: Huh. Well it looks like my bulbs (these) are RGB bulbs. So, putting aside the question of whether it's enough blue to affect your circadian rhythms, it is in fact more blue than you'd get from incandescent?
posted by HotToddy at 4:54 PM on November 11

Note that many "RGB" bulbs often also have some white phosphor LEDs that will have better spectrum reproduction than you'd get from just mixing red/green/blue together. The Color Rendering Index is a measurement of color reproduction faithfulness on a scale of 0 to 100, with 100 being perfect equivalence to incandescent, which corresponds to roughly what you're looking for. Your bulbs are pretty good, having a CRI of 80, so I'm fairly certain they use these white phosphor LEDs.

There may be more blue in the mix for your bulbs than an incandescent, but I doubt it's very much more.
posted by Aleyn at 5:21 PM on November 11