You probably already know that blue light is bad for sleep quality.I’ll write more about this in the future, but for now, some sources: 1, 2, 3, 4.

But what you might not know is that the LED lightbulbs that you almost certainly have in your home emit significant blue light — even the ones that look reddish.

Here’s a nice chart of color temperatures from Simon Sarris:

2700K looks like a nice evening light, right? Well, here’s a spectrogramSpectrograms show the intensity of the various components of a light source. I use a Gossen Mavospec spectrometer to collect raw intensity data, and these charts show that data indexed to the highest level found in the sample. for a 2700K LED bulb I found lying around:

Wavelength (nm) Relative Intensity 380 480 580 680 780 25% 50% 75% 100%
0.7% intensity
at 380 nm
1.0% intensity
at 385 nm
0.8% intensity
at 390 nm
1.1% intensity
at 395 nm
0.9% intensity
at 400 nm
1.0% intensity
at 405 nm
1.6% intensity
at 410 nm
1.9% intensity
at 415 nm
3.2% intensity
at 420 nm
4.7% intensity
at 425 nm
8.0% intensity
at 430 nm
14.2% intensity
at 435 nm
25.4% intensity
at 440 nm
42.5% intensity
at 445 nm
52.5% intensity
at 450 nm
47.9% intensity
at 455 nm
37.7% intensity
at 460 nm
31.7% intensity
at 465 nm
26.2% intensity
at 470 nm
22.6% intensity
at 475 nm
22.6% intensity
at 480 nm
24.8% intensity
at 485 nm
28.9% intensity
at 490 nm
33.6% intensity
at 495 nm
39.0% intensity
at 500 nm
43.6% intensity
at 505 nm
47.8% intensity
at 510 nm
51.5% intensity
at 515 nm
53.9% intensity
at 520 nm
57.0% intensity
at 525 nm
59.2% intensity
at 530 nm
61.7% intensity
at 535 nm
63.4% intensity
at 540 nm
65.6% intensity
at 545 nm
67.9% intensity
at 550 nm
70.1% intensity
at 555 nm
72.4% intensity
at 560 nm
74.4% intensity
at 565 nm
77.1% intensity
at 570 nm
79.3% intensity
at 575 nm
82.3% intensity
at 580 nm
84.5% intensity
at 585 nm
87.5% intensity
at 590 nm
90.3% intensity
at 595 nm
93.0% intensity
at 600 nm
95.5% intensity
at 605 nm
97.2% intensity
at 610 nm
99.3% intensity
at 615 nm
100.0% intensity
at 620 nm
99.9% intensity
at 625 nm
98.8% intensity
at 630 nm
96.7% intensity
at 635 nm
94.6% intensity
at 640 nm
91.3% intensity
at 645 nm
87.1% intensity
at 650 nm
82.0% intensity
at 655 nm
76.5% intensity
at 660 nm
71.3% intensity
at 665 nm
65.3% intensity
at 670 nm
59.7% intensity
at 675 nm
54.3% intensity
at 680 nm
48.4% intensity
at 685 nm
43.1% intensity
at 690 nm
38.3% intensity
at 695 nm
33.6% intensity
at 700 nm
29.2% intensity
at 705 nm
25.6% intensity
at 710 nm
22.3% intensity
at 715 nm
19.8% intensity
at 720 nm
17.6% intensity
at 725 nm
15.2% intensity
at 730 nm
12.9% intensity
at 735 nm
11.0% intensity
at 740 nm
9.6% intensity
at 745 nm
8.1% intensity
at 750 nm
7.5% intensity
at 755 nm
6.3% intensity
at 760 nm
5.8% intensity
at 765 nm
5.1% intensity
at 770 nm
4.7% intensity
at 775 nm
4.1% intensity
at 780 nm

See that spike of blue? That’s bad for sleep.

That spike appears in pretty much every common LED bulb to some degree, because those bulbs use a blue LED as their light source, which is then absorbed by a phosphor coating and re-emitted to form the overall light you end up seeing. But a big chunk of the original blue remains (and often gets worse as the bulb ages).

Now, you’re probably wondering why I said it’s illegal to buy healthy lightbulbs in California.

Well, you might hear about this problem with LEDs and think: I should find old-school lightbulbs that don’t have that blue light spike. Something like incandescent or halogen bulbs. Here’s an incandescent:

Wavelength (nm) Relative Intensity 380 480 580 680 780 25% 50% 75% 100%
3.9% intensity
at 380 nm
4.0% intensity
at 385 nm
4.6% intensity
at 390 nm
5.4% intensity
at 395 nm
5.8% intensity
at 400 nm
6.3% intensity
at 405 nm
7.2% intensity
at 410 nm
7.7% intensity
at 415 nm
8.5% intensity
at 420 nm
9.1% intensity
at 425 nm
9.9% intensity
at 430 nm
11.0% intensity
at 435 nm
11.6% intensity
at 440 nm
12.4% intensity
at 445 nm
13.5% intensity
at 450 nm
14.5% intensity
at 455 nm
15.2% intensity
at 460 nm
16.3% intensity
at 465 nm
17.4% intensity
at 470 nm
18.5% intensity
at 475 nm
19.4% intensity
at 480 nm
20.6% intensity
at 485 nm
21.6% intensity
at 490 nm
22.9% intensity
at 495 nm
24.1% intensity
at 500 nm
25.2% intensity
at 505 nm
26.5% intensity
at 510 nm
27.7% intensity
at 515 nm
28.9% intensity
at 520 nm
30.2% intensity
at 525 nm
31.6% intensity
at 530 nm
33.0% intensity
at 535 nm
34.2% intensity
at 540 nm
35.7% intensity
at 545 nm
36.9% intensity
at 550 nm
38.3% intensity
at 555 nm
39.8% intensity
at 560 nm
41.3% intensity
at 565 nm
42.8% intensity
at 570 nm
44.1% intensity
at 575 nm
45.8% intensity
at 580 nm
47.0% intensity
at 585 nm
48.6% intensity
at 590 nm
50.1% intensity
at 595 nm
51.5% intensity
at 600 nm
53.0% intensity
at 605 nm
54.4% intensity
at 610 nm
55.9% intensity
at 615 nm
57.5% intensity
at 620 nm
59.0% intensity
at 625 nm
60.5% intensity
at 630 nm
62.0% intensity
at 635 nm
63.5% intensity
at 640 nm
64.9% intensity
at 645 nm
66.5% intensity
at 650 nm
68.1% intensity
at 655 nm
69.6% intensity
at 660 nm
71.0% intensity
at 665 nm
72.7% intensity
at 670 nm
73.9% intensity
at 675 nm
75.3% intensity
at 680 nm
76.7% intensity
at 685 nm
78.0% intensity
at 690 nm
79.5% intensity
at 695 nm
80.9% intensity
at 700 nm
82.2% intensity
at 705 nm
83.4% intensity
at 710 nm
85.0% intensity
at 715 nm
86.1% intensity
at 720 nm
87.3% intensity
at 725 nm
88.6% intensity
at 730 nm
89.9% intensity
at 735 nm
91.2% intensity
at 740 nm
92.3% intensity
at 745 nm
93.7% intensity
at 750 nm
94.5% intensity
at 755 nm
95.7% intensity
at 760 nm
96.7% intensity
at 765 nm
97.7% intensity
at 770 nm
99.1% intensity
at 775 nm
100.0% intensity
at 780 nm

So nice! Incandescents have beautiful spectra (and are what I use for evening lighting).

Unfortunately, general-use incandescent bulbs are illegal to sell in the United States as of 2023See here for context. I think this is insane given how strongly light quality can affect health, and I’m guessing we’ll come back around to this issue in the same way we’re currently revisiting the (also insane) intentional fluoridation of tap water.. It’s not really policed, though, so you can usually find them even on Amazon if you poke around.

But if you live in California, you’re subject to an even more draconian regulation: CA Title 20, which regulates “appliance efficiency.” Even separate from the federal legislation, incandescents are illegal to sell in California, and it is actively enforced.

So if you try to ship incandescents from Amazon to a California address, you’ll get this:

“No problem,” you might say, “I’ve heard there are LEDs that don’t have any blue light! They might be pricey, but it’s worth it for my sleep quality.”

And you’d be right! There do exist bulbs like the Soraa ZeroBlue LED, which are built in a different wayMost importantly: they are violet-pumped rather than blue-pumped. Russell Graves has a great writeup about this. and don’t emit blue light. Here’s their spectrum (that’s a violet spike, with nearly no sleep-damaging blue):

Wavelength (nm) Relative Intensity 380 480 580 680 780 25% 50% 75% 100%
1.1% intensity
at 380 nm
1.2% intensity
at 385 nm
1.5% intensity
at 390 nm
3.4% intensity
at 395 nm
8.3% intensity
at 400 nm
21.5% intensity
at 405 nm
48.7% intensity
at 410 nm
73.8% intensity
at 415 nm
70.1% intensity
at 420 nm
46.9% intensity
at 425 nm
28.6% intensity
at 430 nm
16.9% intensity
at 435 nm
10.0% intensity
at 440 nm
6.2% intensity
at 445 nm
4.0% intensity
at 450 nm
3.0% intensity
at 455 nm
2.2% intensity
at 460 nm
2.2% intensity
at 465 nm
2.1% intensity
at 470 nm
1.7% intensity
at 475 nm
1.9% intensity
at 480 nm
2.1% intensity
at 485 nm
2.6% intensity
at 490 nm
4.4% intensity
at 495 nm
7.0% intensity
at 500 nm
11.5% intensity
at 505 nm
18.5% intensity
at 510 nm
27.4% intensity
at 515 nm
37.6% intensity
at 520 nm
48.4% intensity
at 525 nm
57.4% intensity
at 530 nm
63.9% intensity
at 535 nm
67.0% intensity
at 540 nm
68.0% intensity
at 545 nm
66.3% intensity
at 550 nm
63.7% intensity
at 555 nm
60.2% intensity
at 560 nm
56.6% intensity
at 565 nm
53.9% intensity
at 570 nm
51.7% intensity
at 575 nm
51.1% intensity
at 580 nm
51.3% intensity
at 585 nm
53.1% intensity
at 590 nm
56.9% intensity
at 595 nm
61.5% intensity
at 600 nm
67.3% intensity
at 605 nm
73.8% intensity
at 610 nm
80.2% intensity
at 615 nm
86.7% intensity
at 620 nm
91.8% intensity
at 625 nm
95.7% intensity
at 630 nm
98.6% intensity
at 635 nm
99.7% intensity
at 640 nm
100.0% intensity
at 645 nm
98.0% intensity
at 650 nm
94.9% intensity
at 655 nm
90.7% intensity
at 660 nm
85.5% intensity
at 665 nm
80.1% intensity
at 670 nm
74.5% intensity
at 675 nm
68.1% intensity
at 680 nm
61.9% intensity
at 685 nm
56.1% intensity
at 690 nm
50.2% intensity
at 695 nm
44.8% intensity
at 700 nm
39.6% intensity
at 705 nm
35.0% intensity
at 710 nm
30.8% intensity
at 715 nm
26.8% intensity
at 720 nm
23.6% intensity
at 725 nm
20.5% intensity
at 730 nm
17.8% intensity
at 735 nm
15.2% intensity
at 740 nm
13.3% intensity
at 745 nm
11.5% intensity
at 750 nm
10.3% intensity
at 755 nm
9.1% intensity
at 760 nm
8.2% intensity
at 765 nm
7.0% intensity
at 770 nm
5.9% intensity
at 775 nm
5.4% intensity
at 780 nm

Nice! A bulb with no blue light that is energy-efficient enough to be legal to buy… right?

Hmm… what’s this? It’s an energy-efficient LED, so California shouldn’t have an issue with it.

Well… part of CA Title 20 is this little clause:

State-regulated LED lamps with lumen output of 150 lumens or greater for E12 bases, or 200 lumens or greater for E17, E26, and GU24 bases, and manufactured on or after January 1, 2018, shall meet all of the standards shown in Table K-3 and shall have the following:

…

2. A CRI (Ra) of 82 or greater.

California — being a bit of a nanny state, as usual — wants to make sure that you don’t buy any bulbs that have a poor “Color Rendering Index.”

If you go read about CRI, you’ll see a bunch of complicated formulas and processes. But it basically boils down to this:

For each of the eight (yes, just eight) color swatches below, when they’re lit by the bulb in question, how close to the “ideal” color are they?

See the problem here?

Two of the swatches are blue.

So if we have a bulb that intentionally emits no blue light… it’s probably not going to score great on this test.

Lo and behold, the Soraa ZeroBlue comes in with a CRI score of 80.

Is that because it’s a low-quality bulb letting off low-quality light? Not at all — just the opposite. It’s really quite good.

But because of the lack of blue, it has a low CRI. And because it has a low CRI, it can’t be sold in California or shipped to California addresses.

The issue is that it doesn’t have enough of the unhealthy blue lightTo be clear: blue light isn’t always bad — in fact, during the day, it’s necessary. But most of our home light use is in the evening, and blue light then becomes a problem..

And so, if you want healthy lightbulbs in California… you’re in a tough spot. No incandescents, no zero-blue LEDs.

Without going to great lengths, you’re stuck with melatonin-disrupting bulbs. Enjoy your blue light.

Like I said: it’s illegal to buy healthy lightbulbs in California.

Looking for more to read?

Or, more on light:

Russell Graves’ blog has a number of excellent posts on LEDs and lighting in general. I’d start with “How Your LED Lights and Screens are Killing You.”

Simon Sarris also has a good piece on lighting in homes.

And for even more...

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