What is the best solution for circadian-friendly artificial light?

Other Types of Lights LED Light Bulbs
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The light should have the spectrum most similar to that of the sun, and that spectrum should change along the day, just as the natural sunlight does.

The most basic way to do so would be to use a light of ~5500K during the day, and a light that lacks blue and green light; i.e., it should be pure amber, orange, or red during the night, so as not to disrupt melatonin production.

If one wants to be more precise, we’d need a programmable bulb so that it can simulate sunrise and sunset (i.e. changing wavelengths from red to white, and being able to change the intensity from 0 to 100%), which would be great as a sunrise alarm clock; and the light should start and end the day at 2000K, with the whitest being midday at about 5500K. Again, after sunset, the light spectrum should have no emission below ~560 nm to avoid melanopsin-stimulating light (so no output in green or blue light).

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Now, is there any product in the market that would allow us to do this?

I have looked around a lot and couldn’t find anything is close to being good enough.

Maybe the best option is this product: SunLike12-16S from http://sunlikelamp.com/ (I have no affiliation and the owner disowns me for asking too many questions :-)).

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Advantages:

- The SunLike’s spectrums are the best I could ever find. 2200 K and 5600K are the most important ones for our purpose; then, either 3800K or 4000K is good to use briefly after/before sunrise/sunset to “smooth” the transition.

- The version with Zigbee should allow the bulb to be programmed to work by following a certain schedule. Has anyone tried this? Where can I get a Zigbee bridge that works with this?

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Disadvantages:

- The pure red LED is only 3-4 V so the output would be ~300 lumens, which is too dim to use as the only bulb at night after sunset; you would need at least 2 of them to lighten a small-medium size room, and additionally 1 bulb more to be close to you if you want to read.

- The bulb will flicker on the order of magnitude of hundreds of Hz (e.g. 300Hz) when it is mixing colors or CCTs, or when it is not at full brightness. Which means that the bulb will be zero-flicker only when you are using the LEDS at maximum brightness with no mixing (e.g. 100-brightness pure red, blue or green, or 100-brightness 2200 K, 3800K or 5600K — I’m not sure what CTL they use in the LED mix thoght).

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If someone bought this product, please could you share your experience and confirm if the bulb can be set up to do all this?

Thanks for reading

(This review is relevant: Sunlike 13SS E27 Adjustable CCT Bulb (2200K-5600K, CRI97))

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I run the BLF LT1 @2700K. It is my “ready to sleep” light.

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The problem is that just a bit of melanopic light (which peaks at about 480 nm) can disrupt melatonin production (and disrupt circadian bio-rhythms) significantly; according to this study [1] you only need ~1.5 lux. Saturation of this suppression also happens soon; at 305 melanopic lux. That’s why health-wise it’s better to completely avoid blue, green, and ultraviolet wavelengths after sunset. The 2700K spectrum will have some blue and green. But I understand that it may not be practical or desirable for most people to run on a pure red/orange/amber light at night, so a color light below 3000K will be decent for those cases as long as there is contrast between night and day; i.e. daytime is spent with plenty of bright natural or very good artificial light.

Reference:
[1] Melatonin suppression is exquisitely sensitive to light and primarily driven by melanopsin in humans - PubMed(link is external)

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thank you for sharing your research and ideas

Im in USA, I looked at Sunlike, but the price stopped me from proceeding.

300hz flicker would be a deal breaker for me.

I tried the original Phillips hue bulbs… they work OK, but, my phone shows ripple that is not present in Incandescent.

I gave up on LED options until I hear of one that works, flicker free, w high CRI, at a reasonable price.

Here is a recent post about some 3000k LED strip lights… the feature I find lacking, is that the CRI is not 90+

So I just use 100 CRI 3000k Incandescent for my house lighting. It does not seem to cause me any circadian issues, that are associated with LEDs

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4000k

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Here is an LED product that claims Circadian benefits

one of the reviews has these spectrum test results:

CCT: 2342K
DUV: –0.0032
CRI (Ra): 96.0
R9: 81.9

note the negative DUV… I like that pink tint

…

they also have a film grade bulb, that wont show banding from PWM in photos:

I just ordered one in 3000k w 95 CRI, for $18 with free shipping… will share impressionsf

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Hi SunLike, do you mean that this bulb’s white LED is 4000K?

If so, then the bulb would achieve 5600 K by mixing 4000K with green and blue = flickering on camera, unnatural spectrum, therefore wouldn’t serve my purposes. I’ll look into other of your babies.

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Hi jon, thanks for sharing it.

As I see it, the “circadian benefits” claim is partially dishonest marketing, as it seeks to differentiate the product in something that really is not different from almost any bulb below 3000K. While color temperature and light spectrum are different things, it won’t matter much as most LEDs will have very similar light spectrum at these color temperatures (i.e. the worst feature of cheap LEDs is that they have a very pronounced blue peak, but a cheap LED that is <3000K won’t have the blue peak anyway).

Apart from that, waveformlighting’s bulbs are much better than mainstream bulbs in regard to very high PWM frequencies (in the order of 40k-50k Hz) and light spectrum (again, mostly relevant at colder whites, as warm whites are pretty similar among LEDs). I’ve heard that their heat sink is horrible though, so I don’t expect their bulbs to last much, and would rather buy a more expensive bulb from SunLike (their cheaper models are around 30€) which have a great heat sink so that in theory will make up for it by lasting for many years, and also have better spectrum and controller too.

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thanks for sharing what you have heard…

the sunlike link higher up is for a $58 bulb, plus ship from Russia to USA, in my case…

the Waveform is $18, free ship…

since this is my first 95 CRI LED lamp, Im not going to spend the extra, for a light with 300Hz pwm… the waveform pwm is 25kHz… far beyond what humans, and cameras, can see

the sunlike 300Hz, would be terrible for photos

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Philips Hue has several problems:

- Pretty bad flickering when you mix LEDs output or lower brightness. Even at full brightness, with no mixing between LEDs, I’d say their PWM is about 1k Hz.

- Their white LED is awful.

- The colors of their red, green and blue LEDs are not completely monochromatic. So you will notice that when you set it up to pure red, green, or blue, the light won’t look as bright or vivid as e.g. LIFX.

Why is that? Each color LED from Hue has a wider distribution of wavelengths, which when mixed help to create more vivid colors, but when used separately won’t look bright.

LIFX uses the opposite approach: their monochromatic LEDs are actually pretty monochromatic, so they will be very bright when you use pure red, blue or green, but when you mix them up the resultant color will look awful. This is specially noticeable if you set up to yellow color: Hue will make a decent job, while LIFX will emit a greenish light, not yellow.

You can see a review of an old Hue bulb here: Philips Hue A19 bulb LED Light review

So, to sum it up, Hue will be good for night if you set it up to pure red at 100% brightness. But will be bad at everything else (flickering, white light spectrum, etc.). LIFX is worse at creating new colors, but better at everything else, including use at night, as their red light is indeed pure red. LIFX has other disadvantages too, i.e. it often has connectivity issues, it uses Wi-Fi instead of ZigBee (which can be a pro or a con depending on what you prefer), etc.

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[quote=jon_slider]

Incandescent bulbs are good to use at night (but not for daytime). Low blue and green light. They have flickering at 100Hz or 120Hz depending on where you live, but the curve for the PWM is sinusoidal because the fragment has a certain thermal retention that produces an attenuation.

I don’t use them because:

- They still have some blue and green, which I’d prefer to avoid completely.

- They heat up my room, which is already hot (I live in Spain).

- They increase the electricity bill pretty bad, and won’t last much (usually ~2000h or less). However, you could connect a thermistor to the lamp in order to make the incandescent bulbs last longer.

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From when Cree still was involved in LEDs
Cadiant Dynamic Skylight

Close to what you want. Not sure how they are sold now that Ideal bought Cree Lighting.

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Link is broken for me

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https://www.creelighting.com/products/indoor/dynamic-lighting-experience/cadiant

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Thank you! I’ll be checking it.

Edit: I saw that once, but didn’t know where they sold it. It must be expensive as… And requires installation. Apart from that, it may be good (although it doesn’t reach very low color temperatures).

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You might look into this company. These lights have been around for decades. I have one I use for reading and checking print color. Works well. No eye strain. 96 CRI thereabouts. In order to maintain high color accuracy it’s best to change out the bulb(s) every couple years. Litho houses use these for judging press color. School classrooms claim 30% increase with student productivity. There’s data out there but I’m too lazy to go find it again.

Ott Lights

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thank you for adding to my education about LED options

I looked at their bulbs, here is one at 5000k for $16 plus shipping, but I cant find the CRI specs
https://products.ottlite.com/p-480-85w-edison-base-led-bulb-60w-equivalent.aspx

and they dont offer Warm White

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for $18 w free shipping, Im glad I ordered one of these 95 CRI warm white to test:

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At this point, I don’t think there is an automatic or semiautomatic solution that is good enough for the criteria that I stated in the OP. There are many companies out there and there might be options, but these specifications aren’t mainstream, so they may be only accessible for the wealthy.

So I will go with the strategy of just buying a good daytime bulb (5000-5500K, smooth spectrum, not lacking red wavelengths, zero flicker), and a good nighttime bulb to use after sunset (whose spectrum’s output is >560-580 nm, and zero flicker).

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For the daytime, I will go for SunLike bulbs, as I couldn’t find anything better. They’re expensive, but I think they’re worth it and will last many years.

I’m still deciding whether to get 5000K or 5500K:

- The argument is that 5500K is better to entrain circadian rhythms during the day,

- But if you work close to a screen, which works by an RGB system, it will be emitting a blue peak without turquoise at about 450 nm.

- That means that if you use an ambient light of 5500K plus your screen close to you, then the actual spectrum your eyes are perceiving is too blueish.

- So it may be better, health-wise, to get 5000K bulbs, as everyone works around screens nowadays and that will “balance out” the spectrum that your eyes receive. I’ve seen that SunLikeLamps also sells two combinations of 5000K and 5600K CTL in a proportion of 60:40 or 60:40 that result in 5200K and 5300K, respectively. Those would work too. Personally, I’ll be deciding whether 5000K or 5200K.

- Now, regarding the model, light intensity is crucial to entrain circadian rhythms during the daytime. The perfect spectrum won’t matter if you only get a few lux with it. So I’ll choose a at least 15W bulb and will use 2 bulbs as ambient light in the ceiling lamp, plus 1 bulb in a desk lamp close to me (but as indirect light, with the bulb never in my field of vision). Of course, most of the time I seek sunlight and work close to a windows—nothing will ever beat natural light.

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I’ll write tomorrow in regard to a good orange or red bulb for nighttime, but it’s not being easier to find.

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I use the Fireflies NOV-MU with E21A 2000K every night. It is ultra high cri and emits the lowest blue wavelength I’ve ever measured. I also use the Clemence modded Skilhunt H04RC. Both are usb rechargeable and I leave them plugged in when running them at night.

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Pero nada sera perfecto

You might try something like this Indoor growlight with remote

You can have a little plant buddy to live inside too if you want. You can just set the (only) red light to be on for 3 (or 6) hours a day for your sunset. Maybe turn on 1 hour before your other lights turn off.

There are lots of versions of these in many shapes and form factors. For ease, this is a screw in bulb.

I haven’t used this one, but I imagine it will last longer just using red at maybe 14-22 watts of power.

Edit: The linked light has clones sold under different names. They have a typo. It has 28 red (620/660nm), 18 blue, 18 warm white (~1.8-2K) diodes.

This meets your requirements (& of NIH study) if you want no blue or green at sunset.