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

I was on a hike in July during a full moon and those who were sleeping in open air (no tent or bivy bag) struggled to sleep through the night due to the moonlight.

This was in the North West of Australia, so daytime maximums were around 35C. It was too warm at night to zip your tent or bivy closed, so where possible you would try to position yourself so that you could shield yourself from the moonlight during the night.

There were quite a few afternoon nappers in the group until the moon waned a little by the second week.

Proper discussion of harmful emissions from LEDs should instead speak of intensities at a particular wavelength and perhaps ratios between wavelengths rather than an outdated reference designed for blackbodies.

I have fond childhood memories of seeing my street bathed in the bluish-white light from these street lights, especially during those long winter nights when the ground is covered in white snow. I am quite certain that these street lights did not produce a generation of "physiologically unwell" people.

My city has now begun switching to LED lights and I think they look terrific.

The moon is one (1) singular source of light with a known peak intensity, often blocked by trees or clouds, and only at its brightest one day every month. On a full moon night, the moon is high overhead, not directly in your field of view if you’re looking straight ahead.

LED streetlamps are a dozen or more point light sources, directly in the field of view, each one of them individually brighter than the moon. The 4000K LED streetlamps installed on my street last year have a very sharp spike in the short wavelength part of their spectral power distribution (come to my street and I’ll lend you some diffraction grating glasses to see the spectrum for yourself). The LED lamps are also incredibly bright, I’d say 2–4x the luminance of the prior streetlamps or the sodium lamps on nearby streets.

Because the new lamps are brighter, cities save money by using fewer of them, spaced more widely. This causes the light to be less even than past streetlamps, meaning some parts of the street are intensely illuminated and other parts are in shadows. The lamps are shielded at the top, but they shine out to the side at a very wide angle, meaning they still cause a ton of glare from a block away or more. When originally installed they had poor shielding in the direction of people’s second-floor bedroom windows. They’ve since fixed that problem and only people on the first floor still have light shining directly into their windows.

Seeing these and objects they illuminate in your peripheral vision causes the eyes to become bright-adapted (i.e. entirely knocks out night vision) making objects in shadow appear darker than under other lighting, and the whole scene to have very high contrast. (It takes something like a half hour to become dark-adapted once again.) The glare is extremely distracting. Overall they make the street feel like an industrial warehouse.

The light is not like fire, or past streetlamps.

Beyond that, the new lamps are not more energy efficient than modern sodium lamps. Indeed, if you make them more than twice as bright, they use substantially more energy than well made sodium lamps.

When I walk my dog at night I’ve taken to wearing orange safety glasses (basically plastic filters which block out the short-wavelength part of the spectrum). That I can see noticeably better after blocking half the light put out by these streetlamps indicates that there is some problem with their current design. (With the orange glasses, my rod vision continues to function properly.)

LED streetlamps should be at ~2700K CCT or below, with almost no light in the blue part of the spectrum. They should be no brighter than past streetlamps. They should be placed close together and not too high up, and shielded to mostly direct their light downward rather than sideways.

Under such circumstances they would be fine. (LEDs aren’t an inherently bad technology. They have the advantage that they last longer without needing to be replaced. This saves money for city maintenance departments.) Unfortunately current models on the market don’t meet those criteria.

Same story for car headlamps. The current LED headlamps are a safety risk (blinding pedestrians and other drivers with the glare). LED technology could be used to make fine car headlamps; it’s the ones currently on the market that are terrible.

http://press.endocrine.org/doi/abs/10.1210/endo-119-5-2201?j...

http://jap.physiology.org/content/110/3/619.short

Fires and the moon emit very little light at this frequency.

So, "blue" whatever. If you are keeping my yard dark so I don't have to pull the shades just to block out the light, well, win!

Of course, other areas that still feel the need to light up every square centimeter because security, YMMV.

I'll add that I find the current LED streetlight colors better than the orange sodium vapor "malaise" that we've grown so accustomed to.

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

Where 4 lane / artery / highways get brighter, whiter (bluer) lights, while 2 lane feeders and smaller roads have warmer yellow lighting.

It produces an interesting nighttime aerial effect as the color indicates the nature of the street.

I can't find any source to corroborate so I'd love if someone with more worldly travel experience could corroborate.

I first became aware of the phenomenon playing Cities: Skylines, a European developed city builder game which features the multi-colored street lights in European skins.

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

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

That is right, which is why I have a nice project to use a heliostat with optical fibre to use as daylighting for a house interior.

The colour temperature shall have a nice warm glow in early morning and evening, which shall aid sleep preparation. I'll publish a log if I believe the project is successful.

Set it and forget it is the best smart house technology.

http://darksky.org/light-pollution/lighting-crime-and-safety...

It's got nothing to do with intensity, which would be impossible to achieve, for all practical purposes. The article misused the word here. Rather, it's about color temperature.

I think this problem is overblown, because I've not heard similar complaints leveled against mercury-vapour lamps. I've grown up around them nearly all my life.

'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.

Moving is a comically inappropriate response.

Big point #2 (an actual advantage now) is reduced maintenance cost because the lamps (theoretically) last longer between replacements.

The energy efficiency claims were always a red herring.