Feelings of stress can bubble up everywhere, caused by everything from public speaking to cramming for an upcoming test.
To combat this anxiety many people will turn to meditation, deep breathing exercises and other self-care activities.
But recently, a team of researchers at UC Davis looked at whether the built environment that surrounds us can help cut down stress — specifically by changing the color of lighting.
The team conducted an experiment at the aptly-named Color Lab, a joint collaboration between the California Lighting Technology Center (CLTC) and the Center for Mind and Brain (CMB). It combined public speaking, math and neural measurements to see which color of ambient lighting is the most stress-relieving.
And the results were not so black and white, but rather amber.
Jae Yong Suk and Veronica Then from the CLTC and Sreenivasan “Sreeni” Meyyappan from the CMB recently spoke with Insight Host Vicki Gonzalez about the science behind this stress-reducing experiment.
This interview has been edited for length and clarity.
Interview highlights
How did you get interested in this field of research?
SUK: I studied architecture and then I actually focused on building science, the physics in building, particularly interested in lighting… I was actually a lighting designer for more than 10 years in LA, working to design different buildings and streets all over California.
MEYYAPPAN: I'm a biomedical engineer and a neuroscientist by training. I'm just interested in how the brain functions and how we process different things.
THEN: I just graduated from UC Davis majoring in design. I really like this job because it's exactly what I'm looking for, it’s technical and artistic… it’s everything I've wanted.
When you think about interior design and built environments, engineering something like lighting plays a big role in how someone feels, right?
SUK: Exactly, and especially when the architecture starts to adapt LED technology, it became really important for the architects and the interior designer to understand how light actually works in building. So, energy efficiency, human health and well-being, those are very important aspects in lighting design these days.
What exactly is The Color Lab? How does it work?
SUK: The Color Lab is the living laboratory located in the California Lighting Technology Center. It allows us to change the color of light… more than 10 million colors [to] choose from. We actually create the ambient lighting of the color we selected for people to experience inside of the lab.
The laboratory [was] sponsored by two companies. Toyota Boshoku America, the parent company of Toyota… they actually design the interior of the cars. And Seoul Semiconductor, the manufacturer of LED chips. Those two companies were willing to support the study.
Sreeni, you’re in charge of running this experiment to see how color can affect mood, stress and anxiety for the better. How did you approach this?
MEYYAPPAN: We wanted to have a lighting intervention that can help people recover from stress. So, to do that, we wanted to first design an experiment that will induce stress in a controlled way, in a laboratory setting. That’s when we decided to go with a public speaking experiment, which is stressful as you can imagine.
We ask participants to give a speech in front of a live audience. They would have to prepare a speech and then deliver the speech, and then the judges or the audience [would] have a neutral expression… to induce stress among participants. This from a standard protocol called the Trier Social Stress Test. We introduce stress, and then we expose participants to different lighting conditions to see how they recover from the event that they just experienced.
Jae Yong Suk (left) and Sreenivasian Meyyappan (right) analyze results from using different colored lighting to affect mood, stress and anxiety.Alysha Beck/UC Davis
That was the experiment we did for about two years with over 100 participants. We recorded their brain activity and also the physiological responses for stress markers.
As someone who has done a good amount of public speaking and gets stressed out doing it, I can attest that you want the validation of a smile or nodding. But a blank expression can be stress inducing.
MEYYAPPAN: That was the goal of this experiment, and that's the design of it because there's a social evaluation which can stress people out. And in addition to social evaluation, we also had this unexpected math challenge. We ask[ed] them to verbally subtract 13 from 1,022, and if they made a mistake they have to start over from the beginning.
Veronica, you were actually one of the participants as an undergrad. What was it like to take part in an experiment like this?
THEN: It was completely unexpected. Jay actually just volunteered me to do it. First they took me in and had me relax, and take a couple deep breaths. Then they stressed me out by having me give a speech that I was completely unprepared for. That was really scary, it was definitely stress-inducing. I also had to answer some math questions, I thought I was going to do well on it because I minored in math. I was like, “this should be a slam dunk,” but I don't think I got any of the questions.
After stressing me out, they led me to The Color Lab where I was surrounded with amber lighting, red lighting, green lighting. They took my measurements to see which lighting best reduced stress for me.
Did you actually feel a noticeable difference when you went into The Color Lab and you were exposed to different colors?
THEN: For sure there was a noticeable difference. Amber lighting, it's reminiscent of sunset which is why it gives off calming effects. The other lights were either too vivid or too bright, and it just didn’t have the same effect for me.
How does this lighting system in the facility work?
SUK: We have a small closed room and a linear wall-mounted fixture all around, up and down light. And then the light fixture actually has a four-chip LED [with] red, green, blue and amber chips. That’s the way we were able to create more than 10 million different colors, by combining different chips. And then there's also [a] lighting control… that helps us to change the intensity and color selection, color temperature, many different aspects of lighting. It generally creates a very soft illumination inside of this entire room.
Did Veronica's experience track with other participants in The Color Lab experiment?
MEYYAPPAN: Yes. To track participants, like what we did with the experiment when Veronica was the participant, we used EEG measurements which is electroencephalography… just taking a snapshot of your brain. It’s a non-invasive way, there are some sensors placed on the surface of your scalp that just record neural activity.
Sreenivasian Meyyappan (right) adjusts an EEG cap on Veronica Then (left) as part of the experiment.Alysha Beck/UC Davis
We compared their performance under different lighting conditions, and also we asked them their preference. What was remarkable in the study was the participants’ preferences and their neural data aligned. That was instrumental in giving us this science-backed intervention.
You also tested other colors in the spectrum as part of the experiment - red, green and blue. Did it come as a surprise that amber was the most effective overall?
MEYYAPPAN: That was one of the things we kind of hypothesized to be the case. We did a quick pilot before we started this actual experiment. We did a survey where we exposed participants to different lighting conditions, and there, amber did stand out as one of the most relaxing colors. And then we decided [to do] this full experiment that also aligned with the earlier findings.
SUK: You can see there’s colored lights inside airplanes, trains, buses, some hospital spaces. You can see many different colors of light, and we were really curious to know if they have any positive impact [on] the actual user.
It was really surprising to see how the blue, red and green colors, they actually kind of slow down the stress mitigation process compared to white. White is our control color because we always live in white lighting. But amber was the only one [that] kind of facilitated that stress mitigation process.
Veronica Then (left) sits in The Color Lab exposed to green light. Researchers exposed participants to white, red, blue, green and amber light as part of the experiment to see how each colors impacted stress relief.Alysha Beck/UC Davis
How can this be applied to real life situations to actually help people reduce their stress?
SUK: We have been working with UC Irvine hospital and UC Davis hospital team[s] to adapt this technology. Those spaces [associated with] high stress levels, for example like the MRI room and the pediatric rooms, we can actually adapt the ambient lighting with this amber spectrum. While patients are waiting and they are experiencing the high level of stress, we can transition the light from regular white light to amber lighting. That was already adopted in the UC Irvine hospital and we are really working hard to make the same adoption for the UC Davis hospital now.
Is there a lamp that someone could keep in their house or at work to relieve stress?
MEYYAPPAN: We are now working with a company called Maltani Corp. They’re manufacturing these lamps, we’re calling them the Davis Lamp, which incorporates this technology.
An additional important thing about this intervention is that this is a very passive one, where you can combine it with other approaches. Once the environment or your room is set up with this lighting, you don't actually have to do additional effort in terms of the lighting intervention.
What are the other projects you’re working on? It seems like this is just the beginning.
SUK: CLTC is now working on developing [a] human-centric lighting system, which actually allows the system to automatically adjust its color temperature, intensity, the portion of the blue spectrum in lighting.
For example [on] a phone or iPad, we have the function to transition the color temperature of the display from more bluish to less bluish color. That actually supports the circadian rhythm of a human. That project is funded by the Korean government, and we are in the second year of development procedure now.
Do you have amber lighting in your house?
SUK: I have amber lighting, and then I recommend everyone to avoid high color temperature lighting at night. That is the principle of the circadian lighting system. The amber lighting we found from this study is actually much warmer than typical amber lighting we experience in daily lives. Warm LED or incandescent lamps actually have a 2,700 Kelvin range; the amber lighting we found is much lower color temperature [at] 1,700 Kelvin. You cannot just easily buy [it] from the market, but we really hope to adapt this to as many places as possible.
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