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Some cities are taking another look at LED lighting after AMA warning

washingtonpost.com

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Re: Some cities are taking another look at LED lighting after AMA warning

#21

Post by criley2 »

Bud wrote: post #12
bunderbunder wrote: post #5

Seems like there might also be an opportunity here: - Install the ones that keep people awake along highways and suchlike. - Install lights that don't disturb sleep so much in neighborhoods.

No. The lights aren't effective at keeping sleepy people more awake in the moment. They're effective at disrupting sleep over time by disrupting the hormonal system. They should be banned in favor of lower-color-temperature lights.

>They should be banned in favor of lower-color-temperature lights.

As the article indicates, they are less effective at disrupting sleep than a LCD monitor or smartphone.

If we're banning an outdoor light for being less disruptive than your phone, should we also mandate Flux style warm color phones at night by law?

Re: Some cities are taking another look at LED lighting after AMA warning

#22

Post by jqkeller »

I've worked on a few street light retrofit projects and the AMA warning is a little overblown and frankly immediately outdated.

This is off the cuff, but it comes down to circadian rhythms being influenced by the color of light. Before artficial light, the sunrise and sunset have a softer light with a lot more red wavelength in it. This would correspond more closely with the color of light from an incandescent, like 2500-3000 Kelvin. The mid day light has a lot more blue wavelength in it relatively, where it is much more of a White light, I think daylight is like 15,000K. The high pressure sodium, HPS, lights have an orange light in the 2,200K range. The majority of LED street lights being installed are 4000-5000K, so they have a lot more of the blue light. Essentially the blue light tricks your brain into thinking it's mid day and messes with your sleep patterns.

The first generations of LED street lights could really only effectively make the 4000-5000K light. With new generations coming out every 3 months or so though they have been able to create models that can generate the 2500-3000K warm red light, but they're not quite as energy efficienct as the 4000K lamps, maybe 10% or something. The 2500K is actually better for the Dark Sky movements as well and a lot of cities are moving to specify these warmer temperature for those reasons.

There are a whole bunch of other things going on as well. The road way lighting standards were designed around the light patterns of a HPS lamp and haven't been updated to reflect the light patterns possible with LEDs, hence a lot of LED projects have too bright of streets.

For the sleep pattern issues, when you're installing LED lights in your home, you want to put the warm lamps, 2500-3000K, lamps in bedrooms and such. Then for living spaces or offices you'd want to put the 4000K lamps to help keep you awake during the day. There are also lamps/fixtures available that will automatically tune the color output of the light to be in sync with the outdoors to help keep circadian rhythms in sync.

This company has been pushing the tunable lamps hard. http://www.planled.com/archives/portfolio-item/entraining-ci...

http://humancentriclighting.org/ This site appears to be fairly dead, but they were more of an independent group promoting it the last year or two.

Re: Some cities are taking another look at LED lighting after AMA warning

#23

Post by honkhonkpants »

_0w8t wrote: post #16

While that may improve sleep, it may also made driving less safe. With blue light it is easy for eyes to focus. In fact there is a theory that significant increase in myopia during the last 100 years is caused by eye work under artificial light without blue color, like from ordinary light bulb... Edit: I should have written "without blue light in spectrum eyes work harder". Basically any deviation from the spectrum o…

First time I've heard that it is easy to focus blue light.

https://www.google.com/search?q=is+it+hard+to+focus+on+blue+...

Re: Some cities are taking another look at LED lighting after AMA warning

#24

Post by klipt »

criley2 wrote: post #21
Bud wrote: post #12

Earlier quoted context omitted.

No. The lights aren't effective at keeping sleepy people more awake in the moment. They're effective at disrupting sleep over time by disrupting the hormonal system. They should be banned in favor of lower-color-temperature lights.

>They should be banned in favor of lower-color-temperature lights. As the article indicates, they are less effective at disrupting sleep than a LCD monitor or smartphone. If we're banning an outdoor light for being less disruptive than your phone, should we also mandate Flux style warm color phones at night by law?

Why not. I already use flux on my laptop and would love it if my phone supported that too.

Re: Some cities are taking another look at LED lighting after AMA warning

#25

Post by phasetransition »

I'm head of engineering for a company that designs outdoor luminaires for industrial environments, but not street lights. We use LED and other technologies. Like so many things in life, there are aspects of the AMA directive with potential cause for concern, but also combined with a mixed bag of scientific underpinnings. If you have specific questions about LED physics or human vision, I'm happy to give them a go. I also can speak to some of the literature behind the AMA position paper.

Re: Some cities are taking another look at LED lighting after AMA warning

#26

Post by droopyEyelids »

userbinator wrote: post #4

All the studies I've found seem to say something along the lines of "blue light disturbs sleep", which seems like exactly the needed effect if you're driving at night.

You're thinking of 'promoting wakefullness' like a cup of coffee that has an immediate effect that wears off when it leaves your system.

'Disturbing sleep' means they alter your hormone production & release, which is something that begins to affect you over weeks and months.

High color temperature lights disturb sleep- without promoting wakefullnes.

Re: Some cities are taking another look at LED lighting after AMA warning

#28

Post by afarrell »

klipt wrote: post #24
criley2 wrote: post #21

Earlier quoted context omitted.

>They should be banned in favor of lower-color-temperature lights. As the article indicates, they are less effective at disrupting sleep than a LCD monitor or smartphone. If we're banning an outdoor light for being less disruptive than your phone, should we also mandate Flux style warm color phones at night by law?

Why not. I already use flux on my laptop and would love it if my phone supported that too.

http://www.macrumors.com/how-to/use-ios-9-3-night-shift-mode... https://play.google.com/store/apps/details?id=com.urbandroid...

Re: Some cities are taking another look at LED lighting after AMA warning

#29

Post by keenerd »

Let's break down their claims.

> unseen blue light

I have unread negative comments about this sloppy writing.

They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature.

> The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light.

4000K is actually considered fairly mellow. Above 6000K, then things start to get blue. The earliest white LEDs were around 10000K and terrible.

> Now, however, LEDs are available with lower kelvin ratings and roughly the same energy efficiency as those with higher ratings.

And now the higher kelvin lights are even more efficient. White LEDs use phosphors to shift the blue light to longer wavelengths. This is a lossy process. Low-K tints require more phosphors and reduce efficiency. That said, 4000K looks so much nicer than 6000K that the loss is worth it.

> “As a species, we weren’t designed to see light at night,” Siminovitch said.

We've had mastery over fire for as long as we've been a species. Darkness is unnatural to humans.

Moonlight is around 4100K. So it is even more "natural" than 3000K. Should we blot out the moon next?

> it urged cities to minimize blue-rich outside lighting and recommended the use of LEDs no brighter than 3000K.

Confusing color temperature and brightness again.

And now from the AMA's press release:

> Recent large surveys found that brighter residential nighttime lighting is associated with reduced sleep times, [etc]

It seems no one has blinds in their windows. I always carry an eye-mask with me too, just in case.

The AMA press release is very low on actual content so I can't comment on most of it. They are smart enough to avoid mentioning the "blue light causes eye damage" myth for example, sticking to meaningless wishy-washy statements.

If the people raising a fuss over LEDs actually cared, they would have been campaigning against mercury-vapor and high-intensity-discharge lamps for the past several decades. A 4000K LED puts out way less blue light than either of those technologies.

Re: Some cities are taking another look at LED lighting after AMA warning

#30

Post by keenerd »

jqkeller wrote: post #22

I've worked on a few street light retrofit projects and the AMA warning is a little overblown and frankly immediately outdated. This is off the cuff, but it comes down to circadian rhythms being influenced by the color of light. Before artficial light, the sunrise and sunset have a softer light with a lot more red wavelength in it. This would correspond more closely with the color of light from an incandescent, like…

> I think daylight is like 15,000K.

No, it is 5500K or 6500K depending on which metric you use.

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