Hey everyone, welcome back to My Weird Prompts. I am Corn, and I am joined as always by my brother, the man who has probably read more white papers on light-emitting diodes and spectral power distribution than anyone else I know. Herman, how are you doing today?
Herman Poppleberry here. And honestly Corn, that is a very specific but very accurate description of my Sunday afternoons lately. I have been falling down a rabbit hole of solid-state lighting research, and let me tell you, the world of photons is much more dramatic than people realize. It is great to be back in the studio.
We have a really fascinating topic today that touches on something we all experience but rarely think about until it is keeping us awake at night. Daniel sent in a prompt about the way we light our world after the sun goes down. He mentioned Mitzpe Ramon, which is this incredible town in the south of Israel, right on the edge of the Ramon Crater. If you have never been there, it is breathtaking. It feels like you are standing on the edge of the world, looking out into this vast, primordial landscape. And because it is a prime spot for stargazing, they have actually implemented red streetlights to minimize light pollution. Daniel is asking if any other cities are rethinking the assumption that municipal lighting needs to be bright white, and whether there is actual data to support using red or warmer lighting at scale to help with things like insomnia and general wellness.
This is such a great question because it hits that intersection of physics, biology, and urban planning. It is a classic case of a technology being implemented before we fully understood the biological consequences. For most of human history, the night was actually dark. Then we had the fire era, then the gas lamp era, and then the electric era with incandescent and high-pressure sodium bulbs. But in the last twenty years, we have seen this massive, rapid shift toward Light Emitting Diode, or L-E-D, technology. It was sold to cities as this great energy-saving miracle, which it is from a purely electrical standpoint, but we did not really think through the color temperature of that light until very recently. We traded a warm, orange glow for a harsh, blue-white glare, and our bodies are starting to pay the price.
Right, and Mitzpe Ramon is such a unique case because it is an International Dark Sky Park. I have actually stood under those red lights in the town center, and it is a very surreal experience. It feels like you are on the set of a science fiction movie, or maybe inside a darkroom for developing film. But it makes perfect sense for astronomers because red light does not ruin your night vision. I am curious though, Herman, before we get into other cities, what is the actual biological reason why red is better than white or blue when it comes to our sleep? Why does the color of a streetlight three blocks away matter to my brain?
It all comes down to a very specific type of cell in our eyes that most people have never heard of. They are called intrinsically photosensitive retinal ganglion cells, or ip-R-G-Cs. These cells were only discovered about twenty-five years ago, which is relatively recent in the world of anatomy. These cells are not for seeing shapes or colors or movement. Their primary job is to act as a light meter for the brain. They tell our internal clock whether it is day or night. These cells contain a photopigment called melanopsin, which is most sensitive to short-wavelength light. That is the blue and green part of the spectrum. When these cells detect blue light, they send a direct signal to the suprachiasmatic nucleus in the brain. That is the master clock. This signal basically tells the pineal gland to stop producing melatonin. Melatonin is the hormone that signals to every cell in your body that it is time to rest and repair.
So, when we flood our streets with bright white L-E-Ds, which typically have a huge, hidden peak in the blue light spectrum, we are effectively telling everyone’s brain that the sun is up. We are broadcasting a noon-time signal at two in the morning.
Exactly. And red light is at the opposite end of the visible spectrum. It has a much longer wavelength. Those retinal ganglion cells are almost completely insensitive to red light. So, you can have enough red light to see where you are walking or driving, but your brain remains in night mode. Your melatonin production stays on track. It is the least disruptive way to illuminate an environment. It is essentially invisible to our internal biological clock.
That makes sense. But Mitzpe Ramon is a small town of maybe five thousand people. It is a specialized community built around tourism and astronomy. Are there larger cities that are actually doing this? Or is everyone just sticking with the harsh white glare because it is cheaper or because people perceive it as being safer?
There is actually a growing movement, though most cities are not going full red like Mitzpe Ramon. That is still quite rare because red light can make it difficult to distinguish colors, which can be an issue for things like traffic signals or police work. However, many cities are moving toward what we call warm-white or amber lighting. One of the absolute pioneers in this is Flagstaff, Arizona. Flagstaff was actually the world’s first International Dark Sky City, all the way back in two thousand one. They have been thinking about this longer than almost anyone else.
I remember you mentioning Flagstaff before. They have the Lowell Observatory there, right? Where they discovered Pluto?
They do. And because of that observatory, the city has had lighting ordinances since the nineteen fifties. But what is really interesting is how they handled the L-E-D transition. Instead of buying the standard, off-the-shelf blue-rich white L-E-Ds that most cities bought ten years ago, Flagstaff worked with manufacturers to develop narrow-spectrum amber L-E-Ds. These lights look a lot like the old low-pressure sodium lamps, that kind of deep yellow-orange glow, but they are much more energy-efficient. They have almost zero blue light emission. They are essentially the gold standard for municipal lighting that respects both the stars and human biology.
Is there data from Flagstaff on how this affects the residents? I mean, do they sleep better than people in, say, Phoenix or Las Vegas, where the sky is just a glowing purple haze?
It is hard to isolate just the lighting because there are so many factors in sleep quality, but there have been surveys and observational studies. Residents in Flagstaff generally report a much higher satisfaction with their night environment. There is also a very important study out of the University of Exeter that looked at light pollution and health outcomes across several regions. They found a clear correlation between high levels of blue light at night and increased rates of sleep disorders and even certain types of cancer, specifically breast and prostate cancer, which are thought to be linked to melatonin suppression. By using amber or narrow-spectrum lighting, cities like Flagstaff are significantly reducing that biological risk for their entire population.
What about bigger cities? Flagstaff is great, but it is still a relatively small mountain town. Can this work in a major metropolitan area?
Tucson, Arizona, is a much larger example. They have a population of over five hundred thousand people. They recently did a massive retrofit of nearly twenty thousand streetlights. They did something really clever that other cities should emulate. They used L-E-Ds that allow them to dim the lights by ninety percent after midnight in certain areas. They also chose a color temperature of three thousand Kelvin or lower. For context, those really harsh, bluish streetlights you see in many cities are often five thousand or even six thousand Kelvin.
Let's break that down for a second. When we say three thousand Kelvin, that is more like a warm, yellowish light, right? Like the old incandescent bulbs we used to have in our living rooms?
Precisely. The lower the Kelvin number, the warmer and more yellow the light. Three thousand Kelvin is the maximum recommended by the American Medical Association for outdoor lighting. Tucson’s data showed that by choosing warmer lights and using smart dimming, they reduced their total light contribution to the sky by seven percent, even though they were actually providing better visibility on the ground. And they saved millions of dollars in energy costs. It proved that you don't need to blast the city with blue light to have a functional, safe environment.
That is an important point you just touched on. Better visibility does not always mean more light. I think there is this huge misconception that if we make the streets brighter, they are safer. But whenever I see those really bright, unshielded white L-E-Ds, the glare is so intense that I actually feel like I can see less. It is like someone is shining a flashlight in my eyes while I am trying to see something in the shadows.
You are hitting on a massive point in lighting engineering. It is called disability glare. When you have a very bright, concentrated light source, your pupils constrict. This is a natural defense mechanism. But when your pupils constrict, it makes it much harder for your eyes to see into the shadows. It actually reduces your contrast sensitivity. If you use lower-intensity, warmer light that is properly shielded so it points down at the ground rather than into your eyes or up into the sky, you actually improve safety because people’s eyes can stay adapted to the dark. You can see the person walking in the shadows much better under a dim, shielded light than under a blindingly bright one.
It is almost counter-intuitive. Less light can lead to better vision. It is like we have been over-medicating our cities with photons.
Absolutely. There was a famous study in Chicago where they increased the lighting in certain alleys to try and reduce crime. They thought more light would equal more safety. But they actually found that crime increased in some of those areas. Why? Because the bright lights made it easier for criminals to see what they were doing and created deeper, darker shadows for them to hide in. It also gave people a false sense of security, making them less vigilant. The data just doesn't support the idea that "brighter is always safer."
That is wild. So, if we have the data that warmer, lower-intensity light is better for our sleep, better for our eyes, and potentially better for safety, why is the default still that harsh white? Why are we still seeing these blue-white monsters being installed in new developments?
A lot of it was just the timing of the technology. When L-E-Ds first became commercially viable for street lighting, the most efficient ones, the ones that gave you the most lumens per watt, were the cool-white ones. Cities were looking to save money on their electric bills, so they bought the most efficient bulbs available at the time. It is only in the last five or six years that warm-white and amber L-E-Ds have caught up in terms of efficiency. We are basically living with a decade of bad choices because cities are locked into these long-term infrastructure projects. They bought a twenty-year bulb in twenty-twelve, and they aren't going to replace it until it burns out.
So we are stuck in a blue-light purgatory because of a procurement cycle. That is depressing. But you mentioned the tide is turning. Are there other international examples besides Mitzpe Ramon?
Definitely. Look at Fulda, Germany. They became the first Star Town in Germany. They have totally redesigned their lighting to be human-centric. They use lights that are two thousand seven hundred Kelvin or lower, and they use motion sensors. In some areas, the streetlights stay at a very low dim level until a pedestrian or a car is detected, then they slowly ramp up. This minimizes the total light dose that people are getting while they are in their homes. They also have strict rules about shielding, so no light is wasted by shining into the sky.
I love that idea of a light dose. We talk about dosage for medicine or caffeine, but we do not really think of light that way. But we should, because it is a biological trigger. It is a drug that we are forced to consume just by living in a city.
It really is. There is a concept called melanopic lux. It is a measurement of how much a light source stimulates those blue-sensitive cells we talked about. You can have two lights that look equally bright to the human eye, but one could have five times the melanopic lux of the other. If a city chooses low melanopic lux lighting, they are essentially giving their citizens a smaller dose of that wake-up signal at night. It is like the difference between a cup of herbal tea and a double shot of espresso right before bed.
Does this have any impact on the local ecology as well? I know Daniel’s prompt focused on humans and insomnia, but I imagine the birds and insects in these cities are also affected by this "espresso" lighting.
Oh, the ecological impact is massive. This is actually where a lot of the most heartbreaking data comes from. In Florida, many coastal cities have strict ordinances about red or amber lighting near beaches because white light disorients sea turtle hatchlings. They are evolved to head toward the brightest horizon, which used to be the moon over the ocean. Now, they head toward the bright city lights instead and they die from exhaustion or predators. When those cities switched to red or amber lights, the turtle survival rates skyrocketed.
And if it works for turtles, it is probably doing something for the birds and the bugs too. I have noticed that some streetlights are just surrounded by a cloud of dead insects in the morning.
Exactly. There is something called the vacuum cleaner effect, where streetlights pull insects out of their natural habitats. White L-E-Ds are like a magnet for insects, which disrupts the entire food chain. It exhausts the insects and makes them easy prey. Warmer, amber lights attract significantly fewer insects. There is also research showing that migratory birds are disoriented by blue-rich light, causing them to crash into buildings. By fixing our lighting for our own sleep, we are also helping to preserve the local ecosystem. It is one of those rare environmental issues where the solution actually makes life better for everyone involved.
It seems like such a win-win. But let’s get practical for a second. If I am listening to this and I live in a city with those harsh white lights, and I am struggling with insomnia, what is the takeaway? Beyond moving to Mitzpe Ramon or Flagstaff, which sounds lovely but isn't an option for most of us.
Well, the first thing is to realize that you can control your immediate environment. If you have light from a streetlamp bleeding into your bedroom, that is called light trespass. It is literally a form of pollution entering your private property. Blackout curtains are the obvious fix, but even better is to look at your own outdoor lighting. If you have a porch light, change it to a warm amber bulb. It will help you, it will help your neighbors, and it will attract fewer bugs to your door. Look for bulbs labeled as "Dark Sky Friendly" or those with a color temperature of two thousand seven hundred Kelvin or lower.
I actually did that recently. I swapped out my bright white floodlight for a warm amber motion-sensor light. It feels much more inviting and less like a high-security prison yard. It actually makes the house look better, too.
That is exactly the right move. And on a larger scale, people can talk to their local city councils. Many cities are currently in the process of planning their next round of L-E-D upgrades or maintenance. If citizens push for three thousand Kelvin or lower, and for shielded fixtures that prevent light from shining into windows or up into the sky, it can make a huge difference. There is a great organization called DarkSky International that has resources and model ordinances that you can bring to your local government.
Is there any city that has actually seen a measurable decrease in insomnia after changing their lights? That feels like the data point Daniel is really looking for.
That is the holy grail of this research. There are some smaller-scale studies. For example, there was a project in a small village in Iceland where they replaced their high-pressure sodium lights with very warm L-E-Ds and surveyed the residents. They found a statistically significant improvement in self-reported sleep quality and a reduction in the time it took people to fall asleep. But we need more large-scale data. The problem is that it is very hard to do a double-blind study on an entire city. You can’t really have a control group when the whole sky changes color.
Right, you can’t exactly hide the fact that the streetlights turned orange. But the biological mechanism is so well-established at this point. We know blue light suppresses melatonin. We know melatonin is required for sleep. It is not exactly a leap of faith to say that reducing blue light in our cities will improve sleep. It is basic endocrinology.
It is not a leap at all. In fact, the American Medical Association issued a formal policy statement back in twenty sixteen, warning about the health risks of high-intensity L-E-D street lighting. They specifically recommended that cities use lighting with a color temperature of no more than three thousand Kelvin and that all lights be properly shielded. When the leading body of physicians in the country is telling you that your streetlights are a public health hazard, you should probably listen.
That was ten years ago! It is crazy that we are still seeing five thousand Kelvin lights being installed in some places. It feels like a failure of communication between the scientific community and city planners.
It comes down to procurement and lack of education. Most city planners are not biologists. They are looking at budgets and maintenance schedules. They see an L-E-D that is ten percent more efficient and costs five percent less, and they buy it without realizing they are essentially installing a giant sleep-disruption machine on every corner. They think they are being responsible with taxpayer money, but they aren't accounting for the externalized costs of poor health and sleep deprivation.
This makes me think about the broader concept of urban wellness. We talk a lot about walkable cities and green spaces and bike lanes, but we rarely talk about the lightscape. But the lightscape is just as much a part of our environment as the trees or the sidewalks. It affects how we feel and how we interact with our neighbors.
I totally agree. There is a term for this: human-centric lighting. It is the idea that artificial light should mimic the natural cycle of the sun as much as possible. Bright, blue-rich light in the morning to wake us up and keep us alert, and warm, dim, red-shifted light in the evening to wind us down. Mitzpe Ramon is essentially the gold standard for the nighttime part of that cycle. They have embraced the idea that the night has its own character and its own requirements.
You know, it occurs to me that there might be a middle ground. You mentioned Tucson dimming their lights. Could we have smart streetlights that change color throughout the night? Like, white during the evening commute and then shifting to amber at midnight?
That is actually being tested in a few places! Some cities in Scandinavia are experimenting with tunable streetlights. They start the evening with a neutral white light for commuting hours when visibility is most important for heavy traffic, and then as the night progresses, they gradually shift the color temperature down to a very warm amber and dim the intensity. It is like a sunset for the whole city. It follows the natural rhythm of human activity.
That sounds incredible. It is like the Night Shift mode on my phone, but for the entire world. It feels like a much more sophisticated way to live.
Exactly! And the technology exists. It is just a matter of the cost of the controllers and the willingness of the city to manage it. But as the price of these smart systems comes down, I think we will see more of it. We are moving away from the idea of a streetlight as just a dumb bulb that is either on or off. It is becoming a piece of biological infrastructure. It is part of the public health system.
Biological infrastructure. I like that. It frames the issue not just as a matter of seeing where you are going, but as a matter of how your body functions. It takes it from a "nice to have" for astronomers to a "need to have" for everyone.
Precisely. And for the people like Daniel who are asking about this, it is important to realize that we are at a turning point. For the last century, our goal was just more light, more power, more brightness. We were fighting the dark like it was an enemy to be conquered. But now we are realizing that the dark is actually a resource. We need it for our health, we need it for our sanity, and we need it to stay connected to the universe.
That is a very Herman Poppleberry sentiment right there. Staying connected to the universe. But it is true. I remember the first time I saw the Milky Way in a truly dark sky park. It changes your perspective. You realize how much we have lost by drowning out the stars with this orange and white haze. You feel smaller, but in a way that is actually very comforting.
It is a form of sensory deprivation, in a way. We have deprived ourselves of the night. By bringing back red and amber lighting, we are not just helping people sleep; we are giving them back the sky. We are restoring a part of the human experience that has been missing for several generations.
So, to summarize for Daniel, yes, there are cities like Flagstaff and Tucson and Fulda that are leading the way. The data overwhelmingly supports the idea that blue-rich light at night is bad for our melatonin and our sleep. Red and amber lights are the biological solution. And while we might not see every city go full Mitzpe Ramon tomorrow, the movement toward warmer, smarter, and more human-centric lighting is definitely gaining momentum. The science is settled; now the policy just needs to catch up.
It really is. And I think as more research comes out about the link between light pollution and chronic issues like insomnia, obesity, and even depression, the pressure on cities to change will become irresistible. We are finally waking up to the importance of sleep, and that means we have to address the lights outside our windows.
Well, I think that is a perfect place to wrap this one up. It is a fascinating look at something we often take for granted. Next time you are out for a walk at night, take a look at the streetlights. See what color they are and how they make you feel. Notice if you are squinting against the glare or if the light feels comfortable. You might be surprised by how much it affects your mood and your energy levels.
And if they are bright white and shining into your eyes, maybe send an email to your local representative. You have the data now! You can tell them about ip-R-G-Cs and melanopsin. That usually gets their attention.
Exactly. Use the science! Well, thanks for diving into this with me, Herman. It is always a pleasure to hear you get excited about wavelengths and retinal cells.
Any time, Corn. Any time. I could talk about photons all day.
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Alright, that is it for today. We will be back soon with another prompt. Until then, stay curious and try to get some good, dark sleep.
Goodnight, everyone.
Bye.
