These Lights Are Like a Mood Ring for Your Room

Honeybrains cafe in New York has circadian lighting by Ketra, which aims to keep the body’s internal clock aligned with the 24-hour diurnal/nocturnal cycle.CreditMagda Biernat/Ketra

The Honeybrains cafe in Manhattan’s NoHo neighborhood serves curry cauliflower bowls, turmeric omega juice shots and mood-boosting supplements all intended to enhance mind and body.

If you sit at the communal table long enough and gaze up at the honeycomb-patterned ceiling, you just might notice the lights shifting between different shades of white. They, too, are meant to contribute to your well-being, by delivering optimal brightness and color temperature at different times of day.

Honeybrains is an early adopter of a technology that is becoming the next frontier in LEDs: circadian lighting. Just a few years ago, manufacturers of LEDs were struggling to replicate the static warm glow of incandescent bulbs; now most are experimenting with products that offer a range of color temperatures, mimicking the brilliant midday sun, the gentle lapping of candlelight and all the shades and intensities in between. The benefits, lighting companies say, include interiors with happier vibes and improved sleep and overall health for the people who spend time in them.

Circadian rhythms are still mysterious enough to whet the intellectual appetites of scientists. In fact, the 2017 Nobel Prize in Physiology or Medicine was awarded to researchers who identified molecular mechanisms that control the process. Circadian lighting aims to keep the body’s internal clock aligned with the 24-hour diurnal/nocturnal cycle by emitting bright bluish light during the day to suppress the melatonin that our brains produce as a natural sleep aid. As evening approaches, the system switches to dim yellowish light, allowing the hormone to flow freely.

“Whether people are ready for it or not, it’s happening and coming,” said Natalia Lesniak, a senior lighting designer at Lumen Architecture, the New York firm that worked with Vamos Architects to create the lighting for Honeybrains.

“It’s like green building 10 years ago — it’s going to become the default,” said Ms. Lesniak. “And LEDs are the technological advantage that are allowing us to do it.”


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Acuity Brands, Cree, Osram, Philips, USAI Lighting and other companies have introduced what they call tunable or dynamic white LED light fixtures, most of which are intended for offices and other commercial spaces. Philips’s marketing materials say these products even deliver “a stimulus similar to a strong cup of coffee” during the workday.

Many are playing catch-up to Ketra, an eight-year-old brand in Austin, Tex., that works exclusively on circadian lighting systems — or what it calls “natural light.” Ketra’s bulbs and fixtures can be found in Whole Foods Market at Bryant Park in New York, the offices of Squarespace and Vice Media, Manhattan’s TMPL gym, the Art Institute of Chicago, and, yes, restaurants like Honeybrains.

About 10,000 Ketra bulbs were used in the lighting scheme for the Manhattan headquarters of the advertising and design agency R/GA. Lights cycle between warm and cool white over the day, and colors are used for special events and to identify conference rooms.CreditJohn Muggenborg/Ketra

“The lighting we want when it’s bright outside is fundamentally different than what we want when it’s dark outside,” said Nav Sooch, Ketra’s chief executive. “We concluded that what the world needed was lighting that would adapt for the situation and the time of day.”


Ketra started out illuminating commercial spaces, but expanded into the residential market last year, and was acquired by the lighting controls company Lutron last month. Its products can now be operated by Amazon Alexa and Lutron devices, in addition to its own controls and mobile app. The brand sells whole-home systems through audiovisual specialists, with prices from about $5 to $15 per square foot.

Ketra bulbs have red, green, blue and white LEDs inside, as well as sensors that monitor and adjust them to achieve desired light levels and colors throughout the day. Color temperatures range from about 1,400 to 10,000 kelvin. (For comparison, the color temperature of candlelight is below 2,000 kelvin, traditional incandescent bulbs are roughly 2,700 to 3,000, and natural daylight can be well over 5,000.)

The brand’s primary goal is nuanced whites, but when it’s party time, the products also can bathe rooms in a rainbow of bright colors.

For those who want to try circadian lighting on a smaller scale, GE Lighting offers C-Sleep retrofit bulbs (less than $50 a pair from online retailers) and the C by GE Sol lamp (less than $150 purchased online), which similarly change color temperature at different times of the day, and are controllable through an app and virtual voice assistants.

“Part of the original premise was around wellness and bringing people the ability to influence their quality of sleep by manipulating the quality of light they’re exposed to,” said Jeff Patton, the general manager of connected home product management at GE Lighting. “More companies are doubling down in this area because it’s a real benefit to consumers and has implications to our overall quality of life.”

Many studies in recent years have identified health benefits from circadian lighting strategies. A 2017 study by the Lighting Research Center at Rensselaer Polytechnic Institute in partnership with the United States General Services Administration, for instance, found that office workers exposed to bright bluish light during the day fell asleep faster at bedtime, enjoyed better sleep quality and reported lower levels of stress and depression than those who did not.


The deleterious effects of sleep loss are also well documented. In 2006, the Institute of Medicine (now the National Academy of Medicine) Committee on Sleep Medicine and Research published a report citing numerous studies that associated sleep loss with obesity, diabetes, cardiovascular disease, anxiety and depression.

The Lighting Research Center has partnered with the United States Navy to test circadian lighting in submarines; it has collaborated with Mount Sinai Hospital in New York to evaluate the light’s use in recovery rooms for transplant patients; and it has worked with the National Institute on Aging to increase the comfort of people suffering from Alzheimer’s disease.


A display by Ketra shows a room with lighting that changes as the day passes. The daytime look is on top. The bottom shows the lighting in the display room as it gets warmer for evening.CreditDanny Batista

However, Mariana G. Figueiro, the director of the Lighting Research Center, warned that homeowners swapping out a few bulbs shouldn’t expect the same results as participants in a controlled study.

“I’m afraid that some manufacturers are overstating the benefits,” she said. “We caution people that you really need to measure to make sure that you are delivering the circadian stimulus that you need to. Your eyes alone won’t tell you whether you’re delivering the right amount of light.”

To help, the center has developed a metric for evaluating lighting strategies called Circadian Stimulus, as well as an online calculator for estimating the effects of lighting products. The user of this tool, however, will encounter terms like “macular pigment optical density,” “vertical photopic illuminance” and “spectral power distribution,” indicators that it’s probably best left to professional lighting designers.

Another impediment to effective circadian lighting is that few people spend their days in confined environments. We are exposed to wildly different light conditions as we move between city streets, vehicles and offices, and gaze at smartphones, computers and televisions.


“The important thing about circadian lighting is that it’s really a 24-hour light-dark pattern,” Dr. Figueiro said. “If I don’t know what else you’re being exposed to over the rest of the day, I can’t guarantee it’s going to be beneficial.”

Health advantages aside, the promise of consistently pleasant light has been enough to win over some converts. “For us, it’s really more about the feel-good factor,” said Suzan Tillotson, president of the New York lighting design firm Tillotson Design Associates. “We understand that when it’s dark outside, you really want a warmer light. Bright blue light doesn’t feel good after the sun has set.”

That’s one reason Ms. Tillotson used 10,000 Ketra bulbs in her lighting scheme for the new 134,000-square-foot Manhattan headquarters of the advertising and design agency R/GA, where the lights cycle between warm and cool white over the day, but also beam colors for special events and to identify different conference rooms.

“The results have been very favorable,” said David Boehm, the executive vice president of global facilities at R/GA. “We haven’t quantified it, but because the lighting is so adaptive, I think it’s helped people endure long days in what can be a very straining kind of environment — that is, being in front of monitors or presentations all day long.”

One piece of evidence in support of the technology is that employees no longer unscrew bulbs from ceiling fixtures or amass piles of their own lamps to create comfortable lighting at their desks.

“I’m not sure that people even realize it’s there,” Mr. Boehm said.

And that is perhaps the ultimate compliment — the same could be said about daylight on a sunny afternoon.

A version of this article appears in print on , on Page F4 of the New York edition with the headline: Like a Mood Ring for Your Room. Order Reprints | Today’s Paper | Subscribe
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