Blue LED Streetlights Keeping You Awake?

If you’ve played around with “white” LEDs, you already know that there’s no such thing. There’s warm white and cool white and any numbers of whites in-between. And when white LEDs were new, the bluer “cool white” variety were significantly more prevalent.

Enough US states have swapped out their old street lights with LEDs that it may be having a measurable effect on people and on the animals around us. This is the claim in a recent position paper by the American Medical Association’s Council on Science and Public Health. (Report as PDF.)

Science strongly suggests that heavy doses of light can keep people from falling asleep, and that brighter LED streetlamps may be making the problem worse. The AMA report goes a step further, and pins extra blame on the color of the light. Blue light apparently suppresses the production of melatonin which helps you sleep at night. And it’s not just humans whose circadian rhythms are getting messed up — the effects are seen throughout the animal kingdom.

Blue light additionally diffracts funny in your eyeball — we’re sure you’ve noticed the strange appearance of blue LEDs and UV lasers. Add together tired drivers and glare-inducing streetlights, and you’ve got a recipe for disaster, even without taking into account those birds who keep peeping while they should be sleeping.

The benefits of LED lighting are huge, however. From an energy-efficiency standpoint, there’s no comparison. But it may be the case that initial adoption in streetlights ended up being too bright and too blue.

[via The Washington Post]

78 thoughts on “Blue LED Streetlights Keeping You Awake?

      1. There’s more points to worry about.

        Ordinary streetlight lamps shine in every direction and are directed down by a reflector, which makes the point-intensity of the light less. The LED bulbs are piercingly bright spots in comparison, which gives you blind spots if you happen to glance up towards them.

        Blue light messes up with your night vision because the eye’s pupil response is to contract with blue light, which it doesn’t with reddish yellow. The eye assumes that low intensity light is red (sunset) and it automatically increases sensitivity to blue to compensate. If the light is not red but blue then the mechanism that adjusts the eye aperture mistakes the light to be more intense than it is and closes the hole more than it needs to.

        Blue light also breaks down rhodopsin or visual purple which becomes active once the light levels have dropped further still, so once your eyes have fully dark-adapted, the sight of blue headlights or street lights starts to deactivate your night vision much more and much faster than say moonlight, which has the same spectrum as sunlight, or the sight of red-yellow sodium lamps.

        The trouble is that “white” LEDs have unnaturally intense spike in the blue spectrum which isn’t present in either sunlight, moonlight, or any other kind of light that people have evolved with. It’s historically quite unprecedented. Not even fluorescent tubes have it so bad. That’s because LEDs use this intense blue to excite secondary phosphors that produce the rest of the color spectrum – although in cheaper modules that means just yellow.

        1. And I guess this explains why newer emergency vehicle lights are now quite literally blinding.

          Rainy night a few months ago, accident with multiple police in attendance, and there’s room to pass, and I am crawling by at walking pace, not to rubberneck, but because I can’t see a damn thing for either complete blue-out alternating with pitch black, and it’s not until I’m within 10 feet of him I notice the officer with his arms going like a demented windmill trying to wave me on faster to get traffic moving… well sorry buddy, but if I came at even 10mph through there, you’d be a hood ornament.

          1. That’s interesting I experienced a very similar scenario recently but with a big RBT blitz. The intensity of the lights totally cloaked the police office officer attempting to direct me to pull in.

            I attempted to politely point out the difficult I had seeing him amountstvthe lighting he was became quiet rude and aggressive.

            So any members of the police force out there we want to be helpful and do the right thing but we can’t see you amongst the intense lighting.

            Just for the record my situation occurred in Queanbeyan (Australia)

          2. Furthermore, wildly distracting with high refraction corrective lenses because LED Blue DOES NOT SHOW UP IN THE RIGHT SPOT in my vision. It tends to “float” away from the rest of the image, which was very disconcerting until I got used to it. The Blue of the monitor light on an audio board, the Blue sections of an RGB number display on the back of municipal buses–but the worst? The police light bars on Don’t-Hit-Me-Mode. You have to squint and head for the Dark Spot beside the lights, and Heaven Help the officer that’s standing to the wrong side of them, as others have said.

          3. During daylight the intense public safety vehicle flashing lights make sense, but they definitely need a less intense mode to be used night. Most likely its as distracting for those working the scene as it is for motorists who need to pass through.

        2. Every once in a while I like to read the replies to comments seen on this site and then consider the responses I have seen lately on other comment threads around the web. What a beautiful oasis this is by contrast :)

        3. Which Is why I wear yellow sunglasses at night, to kill the blue! But why are there so many brite lights anyway?? I have no trouble driving down roads with no lights, I was my headlights!!!! Lights on the road are way too many and way too brite!

          1. I would agree with this. I was leaving the archery range near my house about a month ago and my motorcycle headlight went out. I was on the trail to leave there and all I had to do was open my helmet visor and stop for 30 seconds to a minute for my night vision to catch up. Then I was on my way. 5 Miles back to the house without a forward facing light, and only 2 street lights, near my driveway. The over lighting of our roadways should be called into question rather than the type of color of that light. We spend so much time accommodating the lowest common denominator without thinking about what it is doing for the 95% of the others on the road.

          2. Why are there so many bright lights? Because despite your assertion safety of both people and vehicles improves dramatically with good road lighting. Your dipped headlights are useless in a typical braking distance at highway speeds when you spot a darker obstacle. This is by design since if you can see another driver than he can no longer see you. Your main beams are useless for this reason. Great for avoiding dear, not so good for whoever comes around the corner and can’t see a thing.

            People don’t spend millions on street lighting and millions more on electricity just for fun.

          3. Walkways adjoin roadways. Perhaps it’s pedestrian security/safety concerns that drive the density of lamps. People complained when sodium vapor lamps started replacing mercury vapor lighting. I imagined people complained when mercury vapor started replacing tungsten street lighting. I can’t imagine what it was like when electric arc street lighting was used. I’m thinking aliens thought to themselves it about damned time they turned those off. No doubt every step in the evolution of vehicle head lights brought complaints.

        4. The solution is… Dont look at them. every single LED streetlight I have seen is well shielded and only if you are trying to look at them directly do they do this… 100% identical to sodium Vapor bulbs that are also point light sources and insanely high Lumen output.

        5. Not all “white” LED streetlamps are the same. Different chips and phosphors produce different temperature light.

          I grow orchids indoors, and a decade ago when I expanded my growing area I bought a 400 watt high pressure sodium lamp, which was state of the art at the time. It output 55,000 lumens mostly in the yellow and green spectrum, which is not a very efficient grow light. Plant leaves reflect green light, they absorb light mainly in the red and blue spectrum. The ugly golden yellow glow made some flowers look like vomit. But the plants thrived, so I kept it going for a few years. But running a 400W bulb in the house heats the reflector to a temperature similar to leaving a stove burner on medium. The risk of fire spooked me so when the chance came to buy LEDs, I shut it down that day. I replaced it with a 145W LED streetlight, whose massive 10kg heatsink remains cool enough to grab with bare hands.

          The first LED fixture I bought was a “warm white”, with a color temperature of about 2700K and an output of 9600 lumens. While it was sold to me as a “direct replacement” for the HPS, it was nowhere near the lumens per watt ratio of the HPS lamp, even after accounting for the inefficiencies of the yellow and green spectral output. After a year of stunted growth, I hung a second LED streetlight near it, which fixed the problem.

          As I was shopping, I found they also make a “true white”, which at 5700K is much bluer, and is far more energy efficient with 145 watts delivering an output around 13,200 lumens. More efficient lighting would make substantially more light available to the plants. But they are so blue that flowers don’t look good under it. After the experience with the HPS’ sickly golden glow, I decided not to buy that one.

          That was six years ago. Since then, I’ve run the math again, and the best choice for grow lighting appears to be high output T5 fluorescent bulbs. They are half as efficient as LED lighting, so they cost a lot more to run. And the bulbs last 1/3 as long as the LED chips, and cost a lot to replace. However, to get the equivalent light from a set of T5 fixtures, the price of the fixtures and bulbs is about a quarter that of the LED fixtures. So unless my electricity triples in price to above $0.35/kWh, the T5s would be the way I’d go today.

          1. The color temperature of the light is the weighted average of the spectrum. It doesn’t tell you what the actual spectral content of the light is. Likewise, lumens measure the apparent brightness to the human eye – it has nothing to do with plants or the absolute light output of the lamp.

            The most efficient plant grow light looks pink or magenta to the human eye. It doesn’t waste any energy producing green light. Those lights get very poor lumens per watt figures, but the plants love it.

          2. Get a spectrometer – I got a cheap one from Edmund Scientific. It lets you clearly see the division of energy in the visible spectrum and is very illuminating as to the quality of the light produced.

            As a real-life example, the work cafeteria always looked both well lit and dark at the same time and all the food looked bad. When I checked the lights with the spectrometer I could see that there was nearly no red in the output. Lots of photons, just so poorly balanced it made for a miserable experience. I think it was mercury-vapor which they tried to balance with some fluorescent fixtures. It wasn’t good at all.

            Another example was looking at the spectrum of clouds in full sunshine. A smooth, continuous distribution. Then looking at leaves under the same sunshine. Almost all colors removed except for a narrow strip of green, which means the rest is absorbed by the leaves.

  1. A problem I’ve been noticing is that the factory tint on one of my vehicles was almost unnoticeable at night under sodium lamps, but under LED streetlamps, it’s very dark. Meaning I cannot see out so well.

  2. I’m having problems falling asleep when reading on my laptop before sleep. If I read a book, even my eyes go to sleep almost immediately. So there is something in here, most definitely.

      1. Like the previous comment, redshift for Linux, or even xflux (the command-line version of flux-gui) since flux-gui has issues with modern linux packages in my testing.
        Also might want to check this if you decide redshift: so you can change the brightness level of the monitor.

        Twilight for Android (not the vampire movie!). And can also dim the screen more, I don’t think it has an option for disable for one hour, but can pause and resume.

        Flux for Windows and I think Mac OSX (don’t have a mac so can’t test, might try to delve with a vm sometime though). Also has a movie mode, disable for one hour, disable until sunrise, and a darkroom mode.

        I’ll even sneek this onto my brother or sister’s devices and say its a feature of the device, unless they get snappy then I uninstall.

        Hope this is helpful

      2. Thanks mate. I was going to recommend F.lux, which I’ve used for years. I just checked out Redshift. It’s open source and fully configurable, so I think I’ll make the change. :-)

  3. It always looks just plain wrong to me that I can see the source directly on lights in the far distance. Why are they not baffled to illuminate a useful area and stay out of eyes – and the sky. A cone of maybe 110 deg or whatever is optimal for illumination and minimizing reflection int eh rain, etc. The sky pollution people must have it all figured out.

    1. “Why are they not baffled to illuminate a useful area and stay out of eyes”

      It’s a cost-benefit calculation. With a narrower cone, they would have to place the lamp-posts closer together to maintain uniform illumination. And with LEDs – which are more expensive – they want to save money so they use modules that have the diodes in an arc that spreads the light up and down the road and have fewer of them.

      Consequently, that means some of the diodes are always pointing in your eye as you drive down the lane.

    2. Sales. The amount of useable light drops off with the square of the distance, so anything beyond 3 times the distance from the target point is wasted.

      However, if the lights were properly baffled they would not act as long-distance advertisements.

      This is why stadium lighting is set to shine well over the playing field and out into the surrounding neighborhood. The stadium owners are using it to draw attention to the operations at the stadium and they don’t care about the annoyance of the locals because they are not the primary customers.

      In street lighting, done right, one would see the light reflected from the street and objects on the street and nothing else unless you were within the cone of illumination looking up. But that would not look good in advertising or architectural materials and so it isn’t something that sells well to the legislators who have to be lobbied to pay for it.

      Ultimately it is easier to produce a lamp that looks like it is lighting the road than one that actually does.

      Keeping it out of the sky is more tricky because the sky is illuminated by the reflection from the roadway.

    1. That’s the effect blue light has on the rhodopsin molecules in the retina, which are responsible for night vision. When they are hit with high energy photons (blue light), they bleach out and the rods stop responding to light.

      When the intensity of blue light is low enough, the rhodopsin regenerates faster than it breaks down, so you get night vision. When you drive under low light but still enough to see in color, you are partially dark-adapted. With blue-yellow “white” LEDs you’re less dark-adapted than with yellow-green sodium lamps.

  4. Everything big in the us?
    Here in the netherlands they started experimenting with bright green led lightning on roadcrossings between meadows. Lately I’m seeing some led lightning around bicicle paths but I haven’t seen them on busy roads yet

    1. I take it you haven’t been at the A15/A16 intersection at night then. Although frankly I don’t see what the fuss is about. The only thing jarring is that the lighting switches from sodium to bluish LEDs, and then back again but in general I don’t have a problem with either.

  5. Why isn’t street lighting red? The color red has the advantage that it isn’t messing with you nightvision as much as other color do. So in short when using red light you can see the lid area fine and when you look into the dark areas you see good enough. While in other colors, for instance white, you nightvision is reduced and you cannot see properly when looking into dark areas,m your eyes need much more time to adjust.
    In order to see at night, there is no need to have colors. I rather have a less strain on my eyes and don’t know if the car in front of me is orange or yellow then to bright lights that blind me from seeing the car at all. Isn’t street lighting all about safety?
    For many many years this is a known fact, so why do the experts that design these lights mess things up so bad?!?!
    It must be because of money, saving energy is just a side effect.

    By the way… the introduction to the article says “there is no comparison to LED’s” well is this really true? Life expectancy of household LED lamps isn’t as good as advertised on the package and fluorescent lamps are quite competitive regarding energy consumption AND endurance. So why would this be better on streetlights that are exposed to the elements. Sure LED technology has a huge potential, but LED lights a more a fashion statement for designers then a necessity. Fluorescent light bulbs have served us well for many years and sodium nitrate streetlights (with their) familiar orange glow worked like a charm. Please think about that for a while.

      1. Sounds like survivor-ship bias to me. Poorer/rural areas are still equipped with older sodium lighting, with no real reason to upgrade before end-of-life. Wealthier areas have already upgraded to the newer, bluer lights because it’s shiny and new.

    1. I like the idea of red street lights – it would definitely create an interesting atmosphere when it is foggy. The main problem I can see is that cars typically have red rear lights and break lights. They might be a little tricky to spot.

      Regarding lifespan of LED’s they seem to last fairly well – I haven’t seen a failure yet, but my oldest is only 4 years old. I’ve had a few CFL’s fail (and a few more get broken) over the years.

      1. Monochromatic illumination leads to color discrimination problems. Under narrow spectrum red, items that reflect that color and those which reflect all colors equally are indistinguishable – done right you would be unable to read a Coke-cola can as the amount of red light reflected would be identical for all portions.

        Similarly, all items that absorb that same color will appear to be black as there are not photons they can reflect.

    2. Main reason is that the eye is not very sensitive to red light especially in the dark, so you would need to spend a lot more energy to lighting. See Purkinje’s Effect:

      Green gives the highest Lumens per Watt.

      “So why would this be better on streetlights that are exposed to the elements”

      Streetlights don’t use fluorescent lights. LPS/HPS are direct arc lights much like neon tubes.

  6. That’s why I’m using “f.lux”, a free program that automatically lower the color temperature of the monitor after the sunset, simulating the sunset colors. Very comfortable for the eyes, so good that I would make it the default setting for all screens with backlight, not only the PC ones.

  7. On a different thought: (I’ve mentioned this before – not sorry). Anyone remember when cities where lit with mercury vapour lights? I just barely do. Cities had a bluish white glow on the horizon. Then they switched to sodium vapour to save power, and cities on the horizon turned amber. Now with LED lights, they’re shifting back to blue (does that mean they’re coming to get us??? sorry, not sorry).

    Anyway – I’ve seen some time lapse video people (artists) have done that covered months or even years. I wish someone would have done one on the colour of cities on the horizon…

    1. I remember the blue mercury vapor and the yellow incandescents which preceded them. Whoops! I’m giving away my age. Here in Topeka Kansas, we have a mix of sodium, mercury and now, blue white leds are being installed. As I look down the road while driving, the led’s look remarkably similar to the mercury lights, except they are slightly brighter. Our electric company will eventually replace them all with led’s. Ikind of like them! Perhaps the bluish white glow brings me back to my childhood in some way.

        1. A pursuit of lumens per watt is why we are now switching from high-pressure sodium lamps to white LED.

          It just happens to turn out that the historically high efficiency of HPS lamps masked another benefit to humans and wildlife (i.e. not emitting large amounts of blue light)

          1. That’s not really the case, since HPS get about 150 lm/W where the typical white LED is more like 75 lm/W and the more advanced ones with external phosphors are about 100 lm/W.

            The reflector needed for the sodium lamp reduces the efficiency somewhat, but it’s still just as good if not better than LEDs. The LED is more attractive because it lasts longer (with reduced light output), which means less maintenance costs.

          2. I will add that another problem with LED’s is that the high lumens/watt is effectively theoretical, and not at all practical. Why? The human eye is very insensitive to blue light. In addition to destroying your night adapted vision, all those lumens of blue light do very little to enhance your perception, than far fewer lumens in the red-orange spectrum would.

          3. “all those lumens of blue light”

            Lumens are a human-vision corrected metric. Blue light doesn’t get very many, while the same radiation output in green light would get lots.

    1. ehmmm… (to:P R. Pemberton) so if I understand correctly you mean that you should always shut up when something new is introduced? Never ask questions, never have doubts, never think for yourself “do we really need this or is this an improvement?”. Hmmm… I wonder in what world you are living. At first you might interpret your comment as an hint for the other commenters to stay positive, but yet your comment by itself is far from positive. It says nothing about the topic only about the commenters (so I assume you have no meaning or knowledge about the topic). How is this adding to a positive turn to this topic?
      And then it came to me… you never wrote you hated that 34%, you might be even one of them… haha you’ve almost got me there. Good one!

      Just one thing in case you aren’t yoking:
      You are right when you would say that there was never a statue raised for a critic.
      But then again, I doubt that there are statues raised for people who never spoke up about anything and prevent the world from mistakes or disaster.

  8. Partially related to this. When my daughter was born in January and we were finally able to bring her home a month later, every time she woke up at night I’d feed her then spend the next hour and half trying to get her and myself back to sleep. Happened to stumble on a lamp called a “Sleep Baby”, which is just an overprice “Turtle Safe” lamp which is just an over-priced red or orange lamp. Ordered a couple of cheap LED’s from large online retailer named after a river, and used those for the table lamps next to were I sat to feed her. Immediately after eating she would go back to sleep and was sleeping through the night by two and a half months. I’d go right back to sleep as well.

    I’ve given a few similar lamps to relatives that recently had their first child. Everyone says they fall right back to sleep as well.

  9. Oh so glad to see the true light of Hell, sodium light going out. It has been a curse for a generation here. Simply the uglyist color to try to see in. In the edge of town commerical area (malls etc.) private interests have eschewed sodium for multi-vapor for some time. Ever see a new car lot lit with sodium light? Ugly! With fuller spectrum light ice and water show up better. If you have any light entering a sleeping area block it out. It’s so dumb to think of filtering color in this case. I can’t imaging making airplane parts in blue light by day and low presure monochromatic orange light at night, but that is the history of why they exist at all. The quality of the seals in sodium lights must be made in China because the replacement lights sometimes don’t last very long. About the only people that could be bothered by LED streetlights are street sleepers ie. the homeless.

    1. Ridonculous.
      So we should have black-out shades on our windows because they’ve chosen to forgo what essentially amounted to candle-light in favor of attempting to simulate daylight in the middle of the night?
      I suppose, then, we should also have lights inside our now sealed-up homes to simulate sunrise… yahknow, that thing that happens every day, naturally.

      1. Perhaps there’s a project: window-sized LCD panels that go dark at bed time and go bright just before sunrise.

        That said, any light that is directed away from the road/footpath is wasted, and lighting to one’s front door is better served by garden lights and sensor-activated spotlights (which are aimed away from houses).

  10. Not a bad idea.
    I did have a truly brilliant idea to use an IR vertical cavity laser (1064nm) to hit the sensor on street lights and turn them off.
    Sort of like a “Deluminator” ™, you only have to hit the area near the sensor even with 0.5mW ie eye safe.
    The older sensors used to be sensitive to orange mostly but these newer ones have a peak in the silicon range so any powerful light from 1100 to 530nm works well.

    Re. laptops causing sleep issues, there would be a market right there for LED “replacement” panels that use RGB LEDs in place of conventional white and have the existing brightness setting used to vary the colour.
    In this case the highest (normal) brightness would be mapped to white and as the brightness dropped the colour would step down through orange to red. Great for that retro-plasma look :-)
    I actually built a yellow LED laptop backlight at ‘Uni and the battery life wasn’t anywhere near as bad as the original broken CCFL averaging about 2 1/2 hrs on a full charge.

  11. Blue LEDs altering sleep is a well known principle; much before I knew about that effect, I always felt extremely uncomfortable when in an environment with prevalent blue light. This is why I try to eliminate/swap all of them on any appliance where possible. Appliance makers should think twice before using blue LEDs for signaling a condition (ON, OK, Warning/Error, etc.) where much gentler (both to the eye and the brain) green, yellow, orange and red LEDs should be used.

  12. I put all Daylight LEDs in my house because I like the clean, bright feel and color of the light and it works well with they style of house I have. However, I made sure that my outside lights are NOT daylight bulbs for this very reason. One of my neighbors even noticed and said thank you. They make LED versions of Edison lights which use almost no current, and look fantastic in outdoor sconces if you have them.

  13. Why do so many people insist on using an “apostrophe s” when they refer to the plural form of LED? Seems obvious that the plural of LED is LEDs. If you want to use the possessive form then add the “apostrophe s” suffix (as in this sentence: The LED’s cathode was cut short)

  14. This article really trying hard to reach for something. When I was a kid, we had mercury vapor street lights, not the orange sodium vapor lights we have now. They were bright bluish white, and I actually liked them way better, as they didn’t mess with true colors as much as the sodiums do. Nobody complained about the color temperature of street lamps keeping anyone awake back then, can’t see why it would now.

  15. The issue is the blue content of the street lights and the angle of the distribution. LED street lights that have a very shallow emission angle (a wider pattern on the street instead of behind and across it) coupled with the high concentration of blue causes disability glare. Everyone that drives under the 4000K or even 3000K street lights has experienced it but probably didn’t realize the cause; probably thought it was the headlights from an oncoming car. There is a NHTSA congressional report from 2007 that covers this issue. It’s only a matter of time before the lawyers take this and run with it.

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