During the day, the block of bungalows and houses at 22nd Avenue East and East Mercer Street looks like most of Capitol Hill. But at night, it looks crazy. This is one of seven test areas in the neighborhood where Seattle City Light swapped the high-pressure sodium streetlights, which emit a warm orange hue, with glaring LEDs. City officials want to replace all 40,000 residential streetlamps in Seattle with the new light-emitting diodes by next year to save energy and money. But the lights cast a sickening hue. "It is a very cold color—zombie blue," says Dan Travers, who lives on the block. "My first thought was that people are going to look scary under these lights."

"It looks like you are in a supermarket aisle," says Andie deRoux, who lives in an apartment building seven blocks west of Travers. Abby Katzman, who has lived on the eastern slope of Capitol Hill for 20 years, says, "I like the energy it saves, but it does seem very cool and wintery."

On the shortest night of the year, just after dark at 11:00 p.m., I walked to each of Seattle City Light's test areas to see what's sparking revulsion from Travers and others who live under the lights. The beams from the high-intensity, light-emitting diodes are striking. The rays turned my skin the color of white taffy and cast crisp shadows on the pavement. "Zombie blue" is exactly right: Like a day-for-night special effect in a vampire movie, the test streetlights create the sort of atmosphere where you almost expect the undead to emerge from the flower beds and begin eating your face. Everyone I spoke to enthusiastically supported the idea of the LEDs—which require 50 to 60 percent less electricity for the same lumens—but most resented the quality of the light itself.

The problem with the new lights isn't just aesthetic. According to Dr. David Avery—a professor of behavioral sciences and light therapy at the University of Washington and the region's leading researcher on the impact of light on human chemistry—the LED lights could interfere with human biorhythms. Certain photoreceptors in the eye's retina react to cooler colors of the light spectrum, sending a signal to the brain that the sun is up. When humans see the blue light, our bodies think it's daytime. "The sensitivity to these cells for the blue and greenish color makes perfect sense, because the sky is blue. So for millions of years, life has evolved with this 24-hour rhythm of blue light being very prominent for part of the day and then darkness," he says. "This is kind of a conductor of a circadian symphony in the brain and body."

According to Avery, "Theoretically, if someone has one of these LEDs or a blue light outside their window, it could fool the eyes and the brain into thinking that the sun is still up, so the melatonin hormone might not rise normally and sleep might be disrupted." Incandescent lights, the standard bulb in homes, are on the red end of the spectrum. (You may think of them as being white, but they're not.) Shifting the city's primary outdoor lighting to blue-hued LEDS, Avery adds, "would be a major change in terms of our environment." Studies suggest that people exposed to daylight at the wrong hours, like those who work night shift, have more health problems such as high blood pressure and obesity, Avery says.

Mayor Greg Nickels wants most Seattle residents to be living under new streetlights by 2015. Seattle City Light intends to install the lights specifically in residential areas—not commercial arterials or industrial zones, which require more illumination than LEDs can affordably provide.

"They would save about nine million kilowatt hours and about $408,000 a year," says Seattle City Light spokesman Scott Thomsen. An LED lamp uses only 50 watts, while traditional high-pressure sodium bulbs require 130 watts and waste electricity on heat. The conserved power roughly equates to the energy used by 750 single-family houses a year, Thomsen says. Moreover, the LED lamps last three to four times longer—up to 18 years—which drastically reduces maintenance costs to the city. (The city currently pays about $100 in labor costs to replace each dead bulb.)

But LED fixtures cost much more. Whereas the bulbs in the existing fixtures (awesomely dubbed "cobra heads") cost about $15, the LED lamps are part and parcel with their fixtures and each costs $300 to replace, says Edward Smalley, Seattle City Light's streetlight engineering manager. "The real payout for the city, to the customer, is not having to go out to change the light." Funding to kick-start the program comes from a $6.1 million federal stimulus grant to reduce energy use. Of that, $1 million will go toward installing the first 2,500 streetlamps next year, assuming the Department of Energy approves the expenditure this summer. If the city council expands the program, new streetlamps citywide will cost about $20 million.

City officials acknowledge the test lights aren't great. (A different brand of LED is being tested at each site, or in some cases the same brand at different levels of brightness.) Although some people like the lights, other people in the test areas have been complaining—in one area, the reaction from residents has been so intense that Seattle City Light is canceling that test site. And it is continuing to look for better technologies. There's a relationship between a light's warmth and how much energy it saves. High-pressure sodium lights, which give off that night orange glow, emit light at about 2200 degrees Kelvin. But the pilot LEDs are between 5000 and 6000 Kelvin. While Smalley acknowledges the new lights are "a lot bluer, for sure, than what we have now," LEDs as warm as the old lights aren't energy efficient enough to be practical. Seattle City Light will begin testing slightly warmer-hued streetlamps in Seattle's South Park neighborhood in late July. "We are looking at 4000 degrees Kelvin and above, so that way we can provide the best comfort for the city and the energy savings that we are looking for."

Anchorage has begun installing 16,000 LEDs streetlamps, San Francisco has announced it will convert 30,000 streetlamps, and Los Angeles has announced plans to convert 140,000 lamps. Smalley says that technology to produce energy-efficient LEDs with a more palatable hue is evolving, with new generations of lights emerging as quickly as every six months.

Considering the bulbs live longer than most pets, the city should take as much time as necessary to pick a light we can live with for a while. "For those folks who dislike the lights, I say stay tuned and look to our next test sites like South Park. We have not locked into what you see out on the street now," says Smalley. If you want to complain about (or—if you're a zombie—praise) the LEDs, you can call Mike Eagan at his desk: 615-1691. You can even request a 10-question survey to express your opinions about them.