MS. SUSAN PAGEThanks for joining us. I'm Susan Page of USA Today sitting in for Diane Rehm. She's on vacation. America is losing its dark skies. Artificial light at night is harming sea turtles, birds and other animals and has been linked to health problems in humans. In our ongoing Environmental Outlook series, we'll talk about the effects of light pollution and efforts to reclaim the night sky.

MS. SUSAN PAGEJoining me in the studio is Bob Parks of the International Dark Sky Association, welcome to "The Diane Rehm Show."

MR. BOB PARKSThank you, Susan.

PAGEAnd Paul Bogard of James Madison University, thanks for being with us.

MR. PAUL BOGARDIt's great to be here.

PAGEAnd by phone from Salem, Mass, we're joined by Dr. Mario Motta of North Shore Medical Center, thanks so much for being with us.

DR. MARIO MOTTAThank you, a pleasure to be here.

PAGEWe invite our listeners to join our conversation with your own thoughts about light pollution and the night sky. You can call our toll-free number 1-800-433-8850. Send us an email to drshow@wamu.org or find us on Facebook or Twitter. Well, Bob Parks, what do we mean when we say the words light pollution?

PARKSLight pollution can be a number of things. It primarily indicates an impact on the environment due to artificial lighting. That can be anything from glare when you're driving down the road or you're walking and the lights are in your eyes. It can be light trespass which is when light goes where it shouldn't be, like in your bedroom window.

PARKSIt also can be the sky glow from the vast quantity of lights above a city which hinder the view of the night sky, the inability to see stars because it just washes out the night sky.

PAGESo Paul, how has light pollution changed in the past 20 years or so? Is it very different now from how it was just in the recent past?

BOGARDYeah, it really has grown quite a bit just in the last 20 years. There is a remarkable graphic that folks can find online if they like from the, what's called the World Atlas of the Artificial Night Sky Brightness that shows. What they've done is taken data from 1996 and estimated backwards and then forwards.

BOGARDAnd you can see a visual representation of the U.S. in the 1950s, the 70s, the 90s and then in 2025 and the growth of, the spread of light pollution is just remarkable from very dark 1950s to in 2025 the entire Eastern part of the country is covered with light pollution and even in the West there aren't too many places left that are still dark.

PAGEAnd what's that website that people can look at if they wish?

BOGARDWell, they can Google the World Atlas of the Artificial Night Sky Brightness. I think they can probably also find it on the International Dark Sky Association website which is darksky.org

PAGEAnd we'll put a link to that up on "The Diane Rehm Show" website as well. Well, Bob, why should we care? What's the problem?

PARKSWell, the impact of artificial light has been one of those things like all pollution it creeps in over a period of time and nobody really notices. We have the same problem with water pollution. We have the same problem with air pollution.

PARKSUntil it gets to a tipping point, nobody seems to care. What we're finding out in just the last ten years, research coming in on the impact on all species is just dramatic. It stems from a change in their behavior. If you have light all night, birds, turtles, other animals can't function as they would have.

PARKSThey can't do the things that they normally would do. You change. You fundamentally change day and night and that changes so many things. We're now finding that the disruption of circadian rhythms is affecting every organism not just animals, every organism down to plants but especially humans.

PARKSHumans, when you disrupt the day/night cycle, you change fundamentally the balance in the body. It changes the secretion of hormones that actually help fight disease. This is something Dr. Motta can talk to extensively.

PAGEWell, Dr. Motta, let me ask you, what's the effect on -- we're going to talk about the effect on sea turtles and on birds but what is the health effect on humans from this light pollution?

MOTTAWell, light pollution is both external and internal. It is two separate issues here. One is the bad lighting we have on the outdoors and that primarily is a glare problem and makes seeing at night worse and this especially affects elderly drivers become, or are more affected by the glare.

MOTTAThe easiest way to envision that is a dirty windshield with the sun shining on it. You're blinded by that because of scatter. The older we get our lenses develop micro-calcification. That's how cataracts eventually develop in the lenses. That scatters the light so if you have a bright glare source basically it's like a snowstorm, you're blinded.

MOTTAThe other human effects, both internal/external, but more internal in a house, if you have bright lights especially blue late at night it suppresses your melatonin. Many people go to bed with lights on. That suppresses melatonin. It turns out melatonin is an integral part of the immune system. You suppress that and cancers that may develop instead of being suppressed may be allowed to flourish.

PAGEIs this a pretty new area of research, the effects of light, blue lights, night lights and so on?

MOTTAThe original concept was raised by Richard Stevens. He's a researcher at the University of Connecticut Medical Center and back in the 80s so it's not very new but at first it was viewed with a lot of skepticism. But since then numerous studies have been done and has placed us firmly on the map.

MOTTAI'm on the council of the American Medical Association's Council on Science and Public Health and we took this on and got some of the best researchers in the world to help me write a 35-page monograph. It was presented to the AMA and they accepted this unanimously as established scientific fact. So the AMA is fully behind the efforts to control light pollution because of the human health effects.

PAGEAnd Paul, in your book "The End of Night," you write about, among other things, the effect on birds. How much impact has light pollution had on birds?

BOGARDWell, it's had a real significant impact. Just in North America alone, we have more than 400 species that migrate at night and especially on nights when we have cloud cover where our lights are being reflected in the clouds. They're drawing the birds off course and toward those lights.

BOGARDSo back through the years, we've had a number of occasions where birds have been attracted to bright lights and circled the lights until they died or were exhausted or they'd run into the towers, that kind of thing. And what we're seeing now especially is that the birds are drawn into our cities where they're trapped and they end up in the daytime and at night running into the buildings, dying that way.

BOGARDWe also have a problem with communication towers all over the country, some tens of millions of these communication towers that these migrating birds are running into as well and the guy wires present a problem for them as well.

PAGEAnd Bob, we know that there's been an effect on sea turtles. Why sea turtles in particular?

PARKSWell, I'm just back from two weeks on the Florida coast doing sea turtle habitat restoration work for the Florida Fish and Wildlife Conservation Commission and what we know is that when mothers go on to the beach to lay their eggs they avoid areas that have bright lights.

PARKSSea turtle hatchlings when they come out for millennia have crawled towards the brightest source in the sky. That has been the stars over water and that gets them into the water safely when they hatch at night. If you have lights from condos behind the beach, when they come out they're drawn to the brightest light source and that often is a parking lot or a road where they never make it back to the water.

PARKSSo our work right now with the Florida Fish and Wildlife Commission is to change out the lighting, to redesign the lighting, to put in lighting that is low-intensity and uses a wavelength that is very warm towards the red spectrum so by getting it out of their most visually-active spectra you can then help them get back to the water.

PARKSSo we're changing out lights over a period. We have a contract for four years so we'll be working with Florida to try and improve that.

PAGEWell, Dr. Motta, there's a big difference is there not between the effect of blue lights and red lights. Why the difference?

MOTTAThe best person for that in the world is Dr. George Brainard. He's a researcher at Jefferson Medical School, runs a sleep lab there and what he's determined in his research is that ordinary bright light, white light, I should say somewhere between 50 and 100 lux will give you suppression of melatonin but blue light will do that with less than 10 lux.

MOTTABlue light is particularly, the pineal gland that produces our melatonin is particularly sensitive to blue light.

PAGEI wonder, Paul, what's the worst place in America when it comes to night pollution? I'm guessing Las Vegas.

BOGARDWell, Las Vegas is certainly the most dramatic, you know, if you're standing on the strip there it's pretty tough to beat that. Times Square was also quite dramatic but I think, you know, the larger point to make with that though is that any major, American city is going to be intensely and overly lit in this way.

PAGEAnd is there a place that has made an effective effort to combat it, that's taken a different course, Bob?

PARKSAbsolutely, since IDA's founding, we're 25 years old this year, several cities in Arizona have really taken the lead by passing comprehensive outdoor lighting ordinances that restrict the quantity and the type of lights you install. Flagstaff was the first and Tucson was shortly thereafter.

PARKSThey have ordinances on the books for over 30 years and they constantly revise them to take into account the changes in outdoor lighting technology.

PAGEAnd how much difference has it made in a place like Flagstaff?

PARKSIt's dramatic. I mean, there's been studies in Tucson for instance that have shown that the zenith brightness, looking directly overhead at Kitt Peak which is just outside of Tucson has not changed over the last 20 years and that's because Tucson values its optical astronomy business around that area.

PAGEWe're talking to Bob Parks from the International Dark Sky Association, Paul Bogard, author of "The End of Night: Searching for Natural Darkness in an Age of Artificial Light" and Dr. Mario Motta, cardiologist at North Shore Medical Center in Salem, Mass. We're going to take a short break. When we come back we'll continue our conversation and we'll take some of your calls. Stay with us.

PAGEWelcome back. I'm Susan Page of USA Today sitting in for Diane Rehm. Let's go to the phones and invite some of our listeners to join our conversation about light pollution and what might be done about it. Let's go to Chris. He's calling us from Louisville, N.C. Chris, you're on the air.

CHRIS CALLER)Thanks for taking my call. I've listened to your argument and your side of it. I just think, you know, is this really an issue in natural selection kind of adjust the balance of, you know, maybe more people get cancer, maybe birds and turtles die. But eventually won't the ones with certain genes push through this and adapt and then, you know, everybody has their light.

PAGEAll right. Chris, thanks so much for your call. Mario, would you like to respond to that?

MOTTASure. We've -- human life has adapted to evolve melatonin's day-night cycle over half a billion years now since we crawled out of the water. And it's remarkable that essentially all mammals and most reptiles have the same mechanism. It hasn't changed in evolution all this time. Our immune system and our melatonin production is really very much the same as almost every other mammal. To think that in just 100 years we're going to evolve to something different is just not going to happen.

MOTTATen percent of our genes are regulated by a day-night cycle. And the -- to disrupt that is basically undertaking a massive experiment with no controls. And we don't know how it's going to turn out. But we do know that there are now a couple thousand papers that have been published in medical literature that shows it's not good and it's causes significant health effects.

PAGEAll right. And Bob Parks.

PARKSI'll just make one comment. That's not natural selection. What we are introducing is artificial. It is unnatural. So to say just wait for natural selection to get its course, we'd like that. And natural night skies are actually dark.

PAGEChris, thanks so much for your call. Now we're joined on the phone by Michigan's Interlocken Pubic Radio -- from Interlocken Public Radio by Mary Stewart Adams. She's program director at Headlands International Dark Sky Park in Michigan. Mary, thanks so much for joining us.

MS. MARY STEWART ADAMSThanks for having me.

PAGESo tell us, what is a dark sky park?

ADAMSWell, in Northern Michigan it's an area of land over which the night sky has been protected from artificial light pollution and light trespass. And we have 600 acres of old growth forest that's right on Lake Michigan looking south and west over the naturally dark skies.

PAGEAnd how long has it been designated as a dark sky park?

ADAMSWell, we received our designation from the International Dark Sky Association in May of 2011, so it's been -- this is our third summer.

PAGEAnd how much interest do you get from people to come to the park and look at the night sky?

ADAMSWe get a lot of interest. We have thousands of guests throughout the season and it's remarkable where they come from. They're from both the local community, around the state, around the region and even around the world. Because International Dark Skies are something that's very important to the lay person who wants to have a direct encounter with the natural environment where there's no light pollution, no noise pollution. And that's what we've protected. In protecting the night sky we've kind of restored the natural order of the area.

PAGESo if you come to your park, what can you see that I wouldn't be able to see here looking at the sky in Washington, D.C. for instance?

ADAMSWell, you're probably seeing the first magnitude stars there and we're seeing the much dimmer stars. But also you're experiencing an environment that has been virtually untouched for thousands of years, since the people native to this land settled there. The Headlands is in the Straits of Mackinac area which has been for centuries a gathering place. And so you have this encounter with the night sky in a natural environment and it really supports the capacity to feel oneself as human being, encountering the natural world the way it has been done for centuries.

PAGEAnd I know that you have studied the connection between the night sky and literature. Tell us about that.

ADAMSWell, what's important to me, because I come at this as a person who is steeped in poetry and in star lore, that I have an experience of the guests that come to the park. Oftentimes they don't have access to a telescope and they think they don't know anything about the night sky. So sharing the once upon a time, sharing the story really can support a person in recognizing that they do have a connection. It's an inherent connection and that it's not inhibited by a lack of technology or even more formal astronomical training.

ADAMSSo, for instance, I will oftentimes start with a very well known nursery rhyme that most folks know, which is Hey Diddle, Diddle from Old Mother Goose. And each of the characters in that particular rhyme corresponds to the constellations that are overhead in the month of May.

PAGEOh, like what -- tell us about that more specifically.

ADAMSWell, Hey Diddle, Diddle, the cat and the fiddle, the cow jumps over the moon. The little dog laughs to see such a sight and the dish runs away with the spoon. We'll start with the dish. So in the month of May, the Milky Way -- excuse me -- the Milky Way lays -- it's flat around the horizon as it can get. And it seems to disappear or run away. And at this point the big dipper or the spoon is directly overhead. In May, the moon is new among the stars of the constellation Taurus, the cow. You have the cat which is Leo, the little dog is Canis Minor so all of the players are there in the night sky.

ADAMSAnd this rhyme is something that most people have access to but they don't really realize it. It's a little ditty that is a way to memorize the constellations overhead.

PAGEYou know, I never knew that. That's great to know. Mary Stewart Adams, thanks so much for joining us on "The Diane Rehm Show."

ADAMSThanks for having me.

PAGEMary is program director at Headlands International Dark Sky Park in Michigan. Well, Bob, how do you get to -- how do you -- it's your organization that designates dark sky parks. How many are there?

PARKSCurrently we have 21. We just designated Chaco Canyon in New Mexico. I wanted to mention that what Mary's talking about over, 75 percent of the population has never seen. And that is what's very tragic about this issue is that over the last 50 years the population has moved closer to cities. Cities have gone brighter. And that means that most people growing up today will never see the Milky Way, will never see a natural night sky, will never be inspired by it. And we think that's pretty tragic.

PAGEHere's -- yes. Here's an email from Todd. He writes us, "We live in Arlington, Texas and my son who is nine years old has never seen the brightest of stars or planets. The Milky Way is only available in a book. I find this very sad."

PARKSWell, tell him to try to take a trip down to Big Ben National Park in Texas. It's one of our most recent designations. It's down on the edge of Texas across from Mexico. It is the darkest night sky in the United States. It's not easy to get to but it is really worth it.

PAGEAnd, Paul, I know that you've also written about the way in which looking at the night sky has been a source of inspiration for many artists over a lot of time.

BOGARDOh, absolutely. I think since the beginning of time since there were human beings. I mean, it's been this experience of walking out your door, whatever that door is, and coming face to face with the universe has been for so long the most common experience of a human being. And now it's become one of the most rare human beings. So I talk in the book about, for example, Van Gough's painting of a starry night, which most of us know and love. And we look at that and we think, boy this guy was a crazy man to see it this way. And well, you know, he had his artistic lessons but he was also seeing a night sky that we just don't experience anymore.

BOGARDAnd it's interesting to think, or maybe sad to think about all the young Van Goughs out there right now who are not having this -- don't have this source of inspiration to their art.

PAGESo Dr. Motta, you've been involved on the legislative level to get laws enacted to protect dark skies. What can be done? What laws can affect this problem?

MOTTAWell, working on Massachusetts right now and we have a bill before the legislature. We're hopeful that it will pass. We've been working on it for some time. Up to this point there are 14 states with laws and they range quite a bit. Maine has one of the weakest but it does have a law. Connecticut has recently intensified its law. They passed one some years ago. And just this past year made it much stronger. Of course it's one of the worst light polluted areas in the country. But the point is, people like the law so much that they asked for more restrictions and more control.

PAGEBut I don't -- what kind of laws? What kind of restrictions affect this?

MOTTAThe simplest one is to have shielding on street lighting, okay. When you have direct lighting into your eye, your pupil constricts. You all know in a dark room you're pupil's nice and wide and you see fairly well in the dark. The moonlight is about one-tenth of a lumen and on a full-moon night you can see perfectly well outside. Typical streetlights give 30 to 50 lumens, way over lit. And if that shines directly into your eye your pupil constricts. And if it constricts, you're seeing maybe one-fiftieth of the light -- from one millimeter to seven millimeters -- one-fiftieth of the light you normally see.

MOTTAIt's the equivalent of driving with your eyes 95 percent closed. We don't do that. But that's what bright lights and hot spots do. And it's a simple solution. Just don't have direct light and make sure -- many new lights -- drivers and people listening to this program will notice the old hang-down lights are being replaced by flat lights. And that's because the lights are now hidden up inside the luminaire so you don't have a bright light shining in your eye. That'll make the streets safer because it won't constrict your pupil.

PAGEBob.

PARKSYeah, this is part of the IDA's mission since its beginning. We've been working with communities and concerned citizens to pass regulations -- sensible regulations such as basically say put the light where it should be. Put it on the ground, put it on the sidewalk. Don't put it in my bedroom. Don't put it in my eyes. If you can engage communities and have this discussion, nobody is opposed to lighting well. We promote quality outdoor lighting. That doesn't mean lighting every street, every corner. It's means lighting areas that are going to improve safety.

PARKSAnd we can do that in a very good way. And with the new LED technology we can do it more efficiently than we've ever been able to.

PAGENow Susie's calling us from Arlington, Va. I think she's been active there on this issue. Susie, hi. Welcome to "The Diane Rehm Show."

SUSIEHi. Thanks for hosting this show, very important conversation. Yes, I live in Arlington County, Va. which is a very progressive community right across the river from D.C. The government is in the process of changing over its regular street lights to LED lighting. And there was, of course, a big hue and cry when the first ones came in because they were very high luminosity and very intense. And so they're having a conversation about that. And they've gone back and they've installed dimmers for, you know, after activities die down at night. But for me it's still a creepy feeling, this sort of blue light.

SUSIENow the argument for these is also compelling however, and that is that it saves a lot of energy. And Arlington wants to save money, they want to save energy and therefore reduce climate change. So there is a tradeoff in some areas but I think bottom line for me would be, as the previous speaker said, just less lighting all around.

PAGEOf course the argument for lighting, street lighting in particular, is that it helps reduce crime. That it makes neighborhoods safer. A lot of cities have argued that lighting up the street has been a factor in that.

PARKSWell, that's unfortunately been the selling point of lighting since Edison. We have done more and more outdoor lighting because it's been equated to more and more safety. Who could be opposed to safety? So it's like salt. A little bit of salt really helps. A lot of salt doesn't make it better. And we need to have a national or worldwide discussion on how much lighting is needed, when do we need it and do we need it. Because we can -- like the caller's talking about, if we just convert to blue rich white light without concern for the impact on drivers and pedestrians, we're not improving lighting.

PARKSAnd energy efficiency can be helped by not just changing to LED but using the right amount of light and not using it when you don't need it.

PAGEI'm Susan Page and you're listening to "The Diane Rehm Show." We're taking your calls. We're going to read your emails, drshow@wamu.org Dr. Motta, go ahead.

MOTTAYes. That's a frequent argument that comes up. And although Bob answered that very well, I'd just like to throw out there numerous studies that have been done on this. And I would challenge the lighting industry to give one study that show excess lighting actually reduces crime. They don't have any. Every time it's looked at, excess lighting actually increases crime. Best example is Chicago. In the early 2000 -- I think it was 2002, they got a federal grand to light up all the alleyways with bright lighting to quote "reduce crime." They ran out of money about halfway through the -- about two-thirds of the way through the project.

MOTTATen years later, looking at the statistics, wherever they put the lighting, crime went up. Wherever they didn't put that lighting because they ran out of money, crime stayed the same or went down...

PAGEAnd I don't understand, why would that be?

MOTTAWhy would that be?

PAGEYes.

MOTTABecause criminals need lighting to attack people. And teenagers hang out in places where there's lots of light. Whenever school systems cut back on lighting, the amount of vandalism in schools goes down. There are about 30 studies on that alone.

PARKSYeah, the details on that were -- it was done in 1998. The lighting in alleys was increased by 250 percent. And they found, after going back later to basically analyze the data to show what a great job they did of increasing safety, crime across the board went up 20 percent over areas that didn't get the lighting. And exactly what Dr. Motta is saying is some crime actually enjoys having more light.

PAGEPaul, what about on roads and highways? Isn't lighting a factor that makes it safer to drive at night?

BOGARDIt can. I mean, it's nice to have particularly intersections at times be lit. But I think that what we're really talking about here is not whether it's lit or whether it's not lit. It's really how are we going to light it? Are we going to have lights, as Dr. Motta was talking about earlier, that are glaring into our eyes making it harder for us to see? Or are we going to have lights that are properly shielded so they're lighting the street and they're helping us to see well?

BOGARDI had -- I remember in researching the book, I was talking to the man who's responsible for lighting one of London's toughest boroughs. And so we automatically think, oh my gosh, he's going to blast light everywhere. And he said to me, you know -- we were sitting at his desk and he said, you know this lamp that's between us, if it were bright enough I couldn't see you. How is that making us safer, you know? So it's really not just about evermore light making us evermore safe. It's how do we use light in thoughtful and responsible ways?

PAGEBob.

PARKSExactly. We need, besides for the conversation, to get federal dollars behind doing real research to show when does outdoor lighting improve safety? When does it reduce accidents? This is a multibillion dollar industry and yet we don't have enough hard date to say yes or no, does lighting actually help?

PAGEHere's an emailer who suggests, "Why don't we tax energy use on lights at night at a high rate, for example, billboards brightly lit at night?"

PARKSOh, I like that. Good luck with getting it through congress.

PAGEWe're talking to Bob Park, executive director of the International Dark Sky Association. And also with me in the studio, Paul Bogard, the author of "The End of Night: Searching for Natural Darkness in an Age of Artificial Light." He teaches creative writing and environmental literature at James Madison University. And joining us on the phone, Dr. Mario Motta. He's a cardiologist at North Shore Medical Center in Salem, Mass. We're going to take a short break. And when we come back, we're going to go back to the phones, take some of your calls and questions. We'll read your emails. You can find us on Facebook or Twitter. Stay with us.

PAGEHere's an email we got from Jeff Chester, public affairs officer at the U.S. Naval Observatory, here in Washington, D.C. He writes, "We established a dark sky site in Flagstaff, Ariz., in the mid-1950s to relocate our largest telescopes, which by that time were useless in the bright lights of Washington." H writes, "Our Flagstaff station has been operating for some 50 years. Thanks to Flagstaff's outdoor lighting ordinances we can still carry out our mission of observing faint celestial objects in direct support of the Department of Defense.

PAGE"Over the past 50 years, the unchecked development of Phoenix, 150 miles to the south, has posed a bigger threat to Flagstaff's station's sky than similar development nearby." Paul, that really shows you how effective Flagstaff's effort on this front had been.

BOGARDYeah, and it's remarkable. If you get the chance to go to Flagstaff and, you know, climb up the mountain and look down on the city, it just looks like a different place. The lighting is different than we normally do it. But I also enjoy visiting Flagstaff because it's an example of what we can do. And it comes back to that point that we want to make about light pollution, that in terms of so many environmental problems, this is one we can so readily handle, we can so readily do something about.

PAGEWell, but how big a deal do you think it is? Does it just affect sea turtles and migrating birds or is it broader than that?

BOGARDYou know, it's so much broader than that. And in fact it goes back to the first caller's questions. I think the point I would make about that is that life on Earth evolved in bright days and dark nights. And for optimal health -- and this includes humans -- we need both, bright and dark. And so we have, at this point, more than 60 percent of invertebrate species and 30 percent vertebrate species are purely nocturnal.

BOGARDAnd then so many other species are corpuscular, active at dawn and dusk. So they've evolved over hundreds of millions or billions of years to rely on darkness for their living. And when we come along and irresponsibly spray our light into their habitat it is so destructive.

PARKSYou know, and advantages and disadvantages, different species in different ways. That's what we don't understand and part of the research that we would love to have done. We know, in some instances, nocturnal animals that were able to feed and forage with impunity, without being seen, now are able to be seen and their numbers dwindle rapidly. When the predators have the advantage because they can see, they change the times of the day that they'll feed. They no longer are diurnal. They are now working the seams. They're going into the evening. They're waking up and doing it during transitions. They extend their feeding cycle. They prosper.

PAGEBut, Dr. Motta, there are any number of humans who work at night, you know, healthcare workers, journalists, law enforcement officials, retail sales. How big of an effect do you think this is having on their lives and health? People who end up working in bright lights late at night.

MOTTAThe international agency for research in cancer in 2007 thought this was a significant enough problem, based on all the data available, that they classify shift workers -- exactly the people who you are talking about, who are constantly changing their circadian rhythm -- they classified that as a Class 2A carcinogen. The only reason it's not a Class 1 is Class 1 means I give you a substance and you develop cancer for sure. Class 2A is at the same level of proof as cigarette smoking, meaning you're exposed to it and a certain percentage will have a higher risk of developing cancer.

MOTTASo if you're a smoker, you're -- you know, not everyone gets cancer, but 1 in 3. That's high enough, so I'll never smoke, but it's not 100 percent certainty. Same thing with lighting at night and shift workers. Some of the best studies were done actually by the Swedish studies, where they involved nurses, based on almost all the nurses in the country were followed over a number of years. And nurses that did shift work and constantly were changing their shift had a one-third increase in breast cancer compared to other women who didn't follow that kind of work cycle. So this is a real development and the World Health Organization through the IARC recognized it as far back as 2007.

PAGESo what can people do to minimize the impact or to protect themselves? Say they are shift workers who are working the night shift, what can they do to protect themselves as far as possible?

MOTTAThat becomes a much bigger question. I mean, obviously we need people to work at night. I work at night. I'm a cardiologist. I get woken up at night and drive in. The answer is you try to minimize the amount of shifting. Possibly have someone work at night for a couple of weeks in a row. That's one way to avoid the continuous suppression of the circadian rhythm by working at night. And when you're at night you try to minimize blue light. And this becomes a very long discussion, but there are simple measures we can do that'll minimize these affects.

PAGEYes. Bob, any advice that you'd have?

PARKSYeah, I would recommend that everybody try to reduce the lighting levels in their sleeping area. This is a really easy step. When you get up in the evening, when you get up at night, go into the bathroom, don't turn the lights on or have a night light that’s red or amber. If you don't change the lighting, you can much more easily get back to sleep. If you've darkened your room, you will sleep better and your melatonins will not be suppressed.

PAGEWell, here's an emailer who asks, "Does the blue light phenomenon also affect children who have blue night lights in their bedroom?"

PARKSReally, really bad idea. When we say blue light -- I want to clarify that. That is blue rich white light. And when you see it, you'll know it. It looks very cold, what we would call cool white. And it's extremely unattractive. When you see people under it they look like they're dead. And so the only reason -- I want to be clear about this -- the absolutely only reason that we have blue rich white light in the environment is LED technology comes from a blue light source. It is then converted to white light with phosphor, and it doesn't do a very good job.

PARKSMost of the light stays in the blue end of the spectrum, which makes it very blue rich, but it also makes it -- if you don't have blue rich white light, LEDs are not as efficient. So for the past few years the Department of Energy and cities have been looking at this once-in-a-century conversion to a new light technology. Getting away from the pink, yellowish lights of the past 50 years, everybody is poised ready to jump into LED lighting. And LED lighting has so many possibilities because it can be dimmed. It can be turned off and turned back on.

PARKSThese are things you could not do with the old technology, but we also have alternatives. Many manufacturers are now coming out with what we would call warm white lights. Much more similar to what you have in your living room or in your bedroom. These lights are only a little less efficient. They're maybe 15 percent less efficient, but people in purchasing decisions, decision-makers in cities, for instance, are looking at the efficiency as the only reason to change. So when they see one efficiency of X and one efficiency is X plus 15 percent, they're making the decision based on that.

PARKSAnd they're not concerned about visual comfort, how this community will accept it. And we have to get the discussion going because we're not opposed to LEDs. We think it is the future if we can manage it, and we can talk people into using lower intensity, dimming it after people are no longer walking on the streets or driving on the streets, and turning it off after midnight, 1:00 o'clock, when nobody is there. We would be able to save 70 percent of our outdoor energy just by embracing this.

PAGEPaul?

BOGARDYeah, and I would just go along with what Bob said. I think one of the things that everyone can do is just to learn more about this issue. I think so many of the problems that we're talking about come from a lack of awareness. So many of us -- if you're under 40 or even 50, you've grown up in a world that's been so brightly lit that it's hard to think that it could be any different. And so I would encourage people to check out the International Dark Sky Association at darksky.org and check out "The End of Night," and just start to learn about these issues.

BOGARDIt really is something we can do something about. And we have every reason to do something about it.

PAGELet's go to talk to Joe. He's calling us from Gadsden, Ala. Hi, Joe.

JOEGood morning.

PAGEGood morning.

JOEI was wanting to get their thoughts on -- it was in the news that Detroit couldn't afford to keep like a third of their streetlights on, if they thought that was a good thing and how the affordability of the technology for the shield, how that plays a part with the municipalities.

PAGEAll right, Joe. Thanks very much for your call. Bob?

PARKSYeah, in cities across the world, not just Detroit, the last few years have been very difficult on budgets. And we're seeing more of what we call switch offs than we've ever seen. Outside of Detroit, because of financial reasons, they've actually removed the lights. They never intend to put them back. We wish that this could be done with more public education. We wish that people were educated as to why they may not need that light, but in most of the instances where we're seeing these switch offs, we are getting statistics back that are supporting what we've been saying for 25 years, which is crime isn't going up, accidents aren't going up.

PARKSThe lights are being removed and the world is still safe. So this is the evidence we need to have these conversations with the federal government, state and local governments to say, let's fundamentally revisit, rethink why we use outdoor lighting and how we use it. We don't want a world without lights. We want lights and we want them to be as efficient as they possibly can.

PAGEMary is calling us from Cincinnati. I think, Mary, you have a particular problem with lighting at your home?

MARYYes, I do. I have a church that's near me. Not close, it's 1500 feet away. And they have those horrible lights mounted on the side of the building, all the way around that sort of blare out into the night, all day sometimes and certainly all night. They maintain that it's for security, but of course, if you stand -- it's the classic case where if you stand in front of this building and look towards it, you can't see anything on the building because the lights have completely made your eyes unable to focus on the doorways or the windows or anything else.

MARYAnd they've done nothing, even over the years -- and this has been going on for a long time -- when I complain or write letters or ask for help or tell them, you know, you can shield it, you can focus it, you can change it, you can redirect it. I'm 1500 feet away and I can make, you know, shadow people on the side of my house. It shines right through my house. Is there some legal action I can take against them? Apparently it's grandfathered in. It doesn't fit under the ordinances that are in my small village.

MARYI feel helpless against those lights.

PAGEOh, gee, I wonder if anyone on our panel has any advice for you?

PARKSYeah, that's a really -- I'm sorry. Go ahead, Mario.

MOTTAOkay. Well, Mary brings up an excellent example of why glare is bad. And I call those insecurity lights. Basically, those are put up by people who think any light is a good light and throwing up wall packs, which is what she's describing, will increase security. I convinced my town by taking pictures of this, because I had a similar situation. There was a church school that had these huge 400 watt security lights, as they call them, shining out into the street.

MOTTAI looked up the accident rate -- and when those went in they have a high rate of accidents at that intersection -- and took pictures of the school. You can't see the school. All you see is the glare spot. So I took that to the city council and that's what helped Gloucester, Mass. have a fairly strong light pollution law by that type of an example. She needs to take pictures, go to their city council and work up a strategy to how to mitigate this.

PAGEI'm Susan Page, and you're listening to "The Diane Rehm Show."

PARKSWell, and I also want to mention that over the last 25 years we've forged really good relationships with a lot of public safety and police. This situation doesn't improve safety at all. In fact, a first responder to an accident and/or a crime, that's blinded by glare, is less likely to be able to see the perpetrator, more likely to be injured by this poor lighting. There is no excuse for glare. It doesn't increase safety. If you ask anybody to produce a study showing any decrease in crime due to glary, over- lit areas -- doesn't exist. So, you know, when you talk to your city officials, ask them to show you the evidence. Tell them that this is causing you sleep problems, that this light trespasses, degrading your life.

PAGEMary, we're sorry to hear about your situation. We hope that you get some relief. Let's go to Ann. She's calling us from Washington, D.C. Hi, Ann.

ANNHi. How are you? Thank you for covering this wonderful topic. I just wanted to point out that City Wildlife, our organization, has joined with many other organizations around the country to monitor and document the bird problem. And on the subject of what citizens can do, citizen science is really helping a lot in developing the data that proves that, in the case of birds, birds are declining from the use of light. And these citizen science projects are now totaling about a billion birds a year that are being killed in these bird glass collisions, a lot of which are attracted by the light.

ANNSo we run a program in D.C. that's similar to other programs around the country, where we get up at 5:30 in the morning and go downtown and pick up the bird bodies in order to document them. And we have a rehabilitation center that rehabs the stunned ones. And we've been able to make great headway with our city in documenting the problem and getting buildings to turn out the lights, particularly problem buildings. So this is something citizens can do. There are these programs around the country. In our case, even if you don't want to get up at 5:30 in the morning, you can take a photo of a dead bird and email to lightsout@citywildlife.org and we'll put it on our database. So we're all coming at this from different angles, but this is one thing the citizens can do to help.

PAGEAll right, Ann. Thanks so much for your call. Bob?

PARKSWell, thank you so much for that work. It's so important. And I wanted to mention that I am based in D.C. also. We are currently talking to the city council and trying to get Washington, D.C. to consider using the model lighting ordinance, which is a lighting template designed by the IDA. It is a comprehensive way for cities to address these issues. We hope that you, the listeners, will mention this to your representatives and tell them, now's the time for some lighting ordinances in the nation's capitol.

PAGEHere's an email that we got from Dave. He writes us, "About 10 years ago my wife and I stayed at Badlands National Park. We were so far away from any commercial lighting that the sky was wondrous. I wish with all my heart that my three grandchildren will someday have the ability to see something like that." Dave thanks so much for your email. And my thanks to our panelists for being with us this hour. Bob Parks, Paul Bogard and Dr. Mario Motta, cardiologist in Salem, Mass., who joined us by phone. Thank you all for being with us.

MOTTAThank you.

PARKSThank you, Susan.

PAGEI'm Susan Page of USA Today, sitting in for Diane Rehm. Diane's on vacation this week. Thanks for listening.