There was something off about the block in Ridgewood where Kara Van Woerden, creative director at a law school, shares a ground-floor apartment with her artist husband, Casey Loose. Starting last fall, the light outside was bluer, harsher than before, but they couldn't quite put their finger on why.

"At first we thought it was because the leaves had fallen off the trees," Loose said. "Then we figured maybe it was from all the Christmas lights."

Van Woerden interjected, "I knew sooner."

As the last of the Christmas lights came down this month, it became undeniable: the new light-emitting diode streetlights that the Department of Transportation is installing citywide had gone in along their street, one of them flooding their bedroom with light. The Department of Transportation started replacing the city's 250,000 yellow sodium streetlights with LEDs in October 2013 under then-mayor Michael Bloomberg, who hailed the project as a conservation measure that would save the city $14 million a year in energy and maintenance.

Windsor Terrace and Kensington were the first neighborhoods to get the LED treatment, and as city installation crews fanned out across Brooklyn, then Queens, complaints started to pour in. A DOT spokesman said in December that the agency has only received 12 complaints about the new bulbs. However, 311 data suggests there have been more: between October 2013 and the present, New Yorkers have made 1,739 311 complaints filed under "Street Light Lamp Dim," three quarters of them in Brooklyn and Queens. The drop-down menu for the DOT complaint form linked on the 311 website includes no option for a light that is too bright, meaning at least some of these complaints are likely about the new LEDs (for the record, the DOT advises people with complaints about lights being too bright to choose "Light shining in the wrong direction").

"Can't they just slap some gels on them already?" Van Woerden asked, leading a reporter and photographer to her street-facing bedroom, where the blue light so disturbed her sleep that she has installed blackout curtains. Before she put them in, she said, she had a hard time falling asleep, and, "I would wake up in the night and just obsess about the light."

"It would be fine if it was just a different" color on the spectrum, Loose said, chiming in.

There is something to this. The lights installed in Ridgewood and across Brooklyn and much of Queens are rated 4,000 degrees Kelvin, a measure not of brightness, but of what's called color temperature. A sodium bulb has a color temperature of around 2,200K, meaning it contains many fewer blue wavelengths, and many more red and yellow ones. Researchers have found that blue lights in the 4,000-5,000K range pose problems, including increased glare, which can hinder road safety, and disruption of people's circadian rhythms. You know how people are telling you to limit your screen time before bed? The same principle is at work here.

Studies have shown that people in preindustrial societies sleep 5 1/2 to 7 hours on average, less than most Europeans and Americans, and fewer than what public health officials typically recommend. Richard Stevens, an epidemiologist at the University of Connecticut, argues that the difference between our sleep and that of people living in the woods is not in time spent asleep, but time spent in relative darkness—people without electricity have light of course, but it's in the form of candles and fires, not LEDs and iPad screens, and thus their bodies are more in tune with their natural sleep-waking cycle. Stevens explained in an interview that blue-spectrum light is similar to that of the daytime sky, and that exposure to it at night drives down people's levels of melatonin, a hormone that regulates sleeping patterns.

At the moment, turning a corner in Ridgewood can mean stepping between the sodium-bulb past and the LED-lit future. (Scott Heins/Gothamist)

"Our whole body has been tuned through the years to respond most strongly at that wavelength to tell us that it’s daytime. That’s the whole key to the electric light issue," Stevens said. "When it’s light during the daytime, sure have it be fluorescent blue. But for our circadian light at night it’s best to have as little of that blue as possible."

There is also some scientific evidence which, though not conclusive, suggests a link between exposure to brighter light at night and cancer, diabetes, and cardiovascular disease.

The American Medical Association issued a set of guidelines in June 2016 that laid out these concerns and called for cities to install LED streetlights rated 3,000K or lower, and filters blocking blue wavelengths. 3,000K lights are only 3 percent less energy efficient, doctors arguing for the guidelines noted, and result in many fewer citizen complaints.

Battles over blue LEDs have played out as cities around the country have embraced their use for streetlights without taking seriously factors beyond the cost savings. Notably, in Davis, California, outcry over the installation of 4,000K fixtures prompted the city to halt the process within days of it starting and replace nearly half of the 1,400 installed in that period with 2,700K ones, at a cost of $350,000.

"They actually spent the money because everyone was going so crazy," said Susan Harder, a retired gallery owner, trained light designer, and activist with the group Sensible and Efficient Lighting to Enhance the Nighttime Environment. "The technology is vastly improving every second, but [city transportation engineers] continue to send out these old specs that were badly thought out in the first place."

New York City's LED program was rolled out without public hearings, but Margaret Newman, DOT chief of staff under Bloomberg, participated in a panel discussion in 2013 in which she said, "People have different preferences, which is why I think some of this gets very subjective. But then there's the science, which is clear in terms of how our vision works. Most people it seems, like around the city, have been asking for white light. They like it when it's whiter...They tend to feel that it's potentially safer."

Academic research offers mixed conclusions as to whether increased lighting leads to reductions in crime—the NYPD, though it routinely lights up public housing developments like the Fourth of July, won't weigh in on the subject—but common sense tends to suggest that it's so.

(Scott Heins/Gothamist)

"I like them," Queens resident Mariana Gomez told Gothamist in an email. "I saw someone comment on the fact it makes New York 'look like a strip mall' and frankly, I just think that's stupid. As a young woman, walking home alone at night is one of my greatest fears, especially in areas that are dimly lit or have these grimy yellow looking lights, because you never know what creep is lurking or who's going to see you if God forbid something happens. Too many young girls in NYC are going missing, so if this helps lessen that number even a little, then I appreciate the city for putting these lights up."

Since the DOT started the replacement process, confusion has reigned. The citywide replacement was supposed to be complete by the end of the 2016. The DOT's new estimate is the end of 2017. Last May, Mayor de Blasio told WNYC's Brian Lehrer that the DOT has "been toning those lights down in many parts of the city," and advised listeners to call 311 if they felt that lights on their block were "too bright." "We will send out a crew, and if we think it needs an adjustment, you know to make it less intense, we'll make that adjustment," he said.

A request that I submitted to the DOT last summer, citing de Blasio's radio appearance, elicited a form response from DOT customer service saying that the fixture near my apartment was the lowest wattage used by the department, and that a "field survey indicated that light is installed properly."

Mayor's Office spokesman Austin Finan wrote in an email, "The mayor was referencing DOT's work with the LED fixture manufacturer to address community complaints by reducing the wattage and switching the fixtures to alter the spread of light and prevent it from going above the fixture's horizon." Wattage does not seem to be at issue in the project, though the DOT did switch to 72-watt LEDs from a first round of 78-watt LEDs midway through the project, and switch to fixtures that throw light less, according to DOT spokespeople. Inadequate shielding, or making sure lights only point down at the ground, is another complaint of light pollution activists, however, this too is a separate issue from the harshness of the new blue streetlights.

A City Council bill that calls for the city to cap LED streetlights at 3,000K has been stalled in committee since it was introduced in June 2015.

After several months of email correspondence requesting further information for an article, a DOT spokeswoman wrote back, "DOT will move forward in installing 3,000K LED street light fixtures given their lower cost; softer aesthetic quality; the AMA recommendations; and the timing of the contracting process to procure the LED street light fixtures in Manhattan, the Bronx, and Staten Island."

A quick glance between the lines will reveal that there are no plans to stop installing the harsh, blue 4,000K fixtures in Brooklyn and Queens, or to replace the ones that are already installed there. The LED bulbs the city is using have a lifespan of 7-20 years, according to various DOT statements.

For the moment, Ridgewood is a patchwork of yellow and blue light. To ride down Onderdonk Avenue, a one-way arterial that cuts east through the neighborhood and is lined with sodium lights, is to soak in the glow of a nearly extinct reality. Turn a corner here or there and the atmosphere changes abruptly, to what Brooklyn writer Erick Lyle described in a phone call as "authoritarian...a science fiction reality where true night has been eradicated, where you’re always awake and always on call."

"Now I notice the workers" from the DOT, said Casey Loose, the Ridgewood resident. "I saw them the other night going up and down Catalpa [Avenue] with a cherry picker."

Before long, the orange-yellow glow of the old lights, a piece of waking experience familiar to anyone alive in an industrialized society right now, is likely to become a nostalgia piece, to be pointed out in movies like appearances of people smoking on airplanes. The variable, in New York and elsewhere, is just how blue the light that replaces it will be. In Ridgewood and the rest of Brooklyn and Queens, the answer seems to be, unless the DOT changes its mind, very.