Michael Siminovitch, PhD, a leading expert in lighting and circadian health, discussed the importance of circadian lighting in his 2024 Wellness Academy presentation. In this Q&A, Dr. Siminovitch answers questions from the impact of light on our daily lives to its role in energy efficiency and health.
Whether you’re interested in optimizing your home for better sleep or curious about the future of lighting technology, Dr. Siminovitch offers practical advice and thought-provoking insights that can help you make informed choices. Read on for highlights from his illuminating talk.
About the expert: Michael Siminovitch, PhD
Michael Siminovitch, PhD, is the director of the California Lighting Technology Center (CLTC) and associate director of the Energy Efficiency Center at UC Davis. He established CLTC to support collaborative efforts among representatives from private industry, public agencies, and utilities. CLTC projects accelerate the development and commercialization of energy-efficient and biologically appropriate lighting technologies for both residential and commercial applications. He co-authored the proposal to establish the Energy Efficiency Institute at the University of California. In 2008 he was awarded the Art Rosenfeld Endowed Chair in Energy Efficiency.
Q&A with Michael Siminovitch, PhD
This transcript has been edited for clarity.
Q: I’m still using old incandescent bulbs. What kind of lights should I choose once those run out, and how do I know which is best for different uses?
Dr. Siminovitch: Yeah, that’s an excellent question. And it’s one that many people face. Although incandescent can be a pretty nice light source, they’re not very energy efficient.
We’ve phased them out, particularly in California, where the California Energy Commission regulates the lamps that are for sale in the State. UC Davis was instrumental in putting together the color spectrum specification for that, which required a much broader spectrum than you might get with an energy star lamp or a lamp you might buy in Texas.
So, at first level, the lights you can buy in the hardware store, the grocery store, and by law, are pretty good if you live in California. They have a broad spectrum and are required to produce 2700 Kelvin, a slightly reduced color temperature, because we were very concerned about the melanin content in homes.
So those are not a bad choice. A more sophisticated, second-level approach would be the idea of introducing amber lighting, which requires a bit more homework. And some of the suggestions I made in the video, including things like amber intervention under the bed or in the bathroom, are good techniques.
Additionally, a third-level approach, I would look at commercial technologies. My website has a lot of information, but that’s basically the three levels of intervention I would consider.
Q: There has been a keen interest in knowing what is available at this point in terms of making the adaptations. And so are these things people are moving piece by piece, bulb by bulb, strip by strip, in terms of both the nature of the light, the amber tones for the evening, etc., and then also the energy efficiency aspects. Are there clear product labels when choosing lights with energy efficiency, dimmable settings, and circadian-friendly options like amber tones?
Dr. Siminovitch: Yeah, again, that’s a great question because it’s very timely. Basic energy-efficient lighting is widely available and used today. So, when you go into a hardware store, you can have a good level of trust that you are purchasing an energy-efficient, good-colored, and good-spectrum light source because that is the standard approach.
The next level approach, which is more circadian sensitive, would look at the idea of introducing an amber spectrum and in conjunction with sensors.
There is a good, better, and best approach here. Commercial outlets sell inexpensive technologies that you can use to introduce amber into your bedroom, bathroom, and/or hallway. Purchasing these and creating an amber-based system for your bathroom, bedroom, and hallway will take you to the “better” level because it’s on top of the standard lighting that we’re all used to.
The more sophisticated amber level requires a very high level of tuning, specifically spectral tuning and controls, which are new things you might see in a hospital or in a health care clinic. And that is where we’ll see it first, and then that will gradually reduce to home usage. But there’s very good solutions today that you can put in inexpensively, less than $100 and instrument your home with an amber spectrum.
Editors note: Examples of guidelines Dr. Siminovitch provided on starting with simple modifications like plug-in amber night lights and see how you like it. The basic guideline is the light source should be:
- Amber in the 2200 Kelvin region
- No blue content if they don’t reference a color temperature
Examples of bulbs, strips, and night lights. *These are not recommendations, just examples.
- Amber light bulbs 2200K
- Amber Night Lights: example 1, example 2
- Amber strips
Q: That’s great. A lot of people are worried about things like seasonal affective disorder, which is often treated with light. Is a circadian healthy home, you know, kind of a thoughtful, lighted home prevention for seasonal affective disorder, or, in your opinion, is the bright light that’s used in the mornings for treating seasonal affective disorder the right way to use light?
Dr. Siminovitch: The way I typically look at this problem is what we’re doing in the evening, is really hurting us. All of the light disruption, the computers, the excessive light living room, it’s not good for us. And we have the numbers on that. I worry less in California about suppressing melatonin during the daytime because people get outside, and you typically get enough circadian entrainment just walking out to the car or from the parking lot.
Where I do start to worry is for the homebound, the people who are, say, in hospitals or in health care, or elderly people who don’t get out. That’s where we are concerned about the seasonal effect because they are not getting enough light.
Some of the assisted living environments are in tune with this and move patients into sunrooms or spaces that are exposed to more light, you know, like the old TB wards that we saw in the 40s and 50s where people were put into conservatories with lots of light as healing.
They knew something; they knew that people needed to be exposed to bright light. I’m not that worried about circadian entrainment in homes, but I am more worried about the light at night. I think that is much more damaging.
Q: Following up on that, would you say that it’s not an issue of having too little light in the morning, but too much light through the evening?
Dr. Siminovitch: Yes, correct. But it is not solely what we are doing at night that’s really, really hurting us, because I think entertainment happens. We are more concerned with appropriate circadian environments. Students are a good example of this. I call them the canary in the cage because we see an enormous circadian disruption at nighttime with students.
They walk around campus all day, so they get lots of exercise, but their routines are disruptive at night. So, we need to be mindful of what we’re doing at night.
In places like Canada, or Northern Europe, where people live in darkness for much of the year, they actually need more light exposure in offices and homes. Our offices don’t have enough light, and we’ve spent years reducing light inside the office for energy purposes, but now we need to rethink that.
Q: What is your thought about light therapy and its uses? In your lecture, you mentioned related light exposure for seasonal affective disorder, and then you showed the work that you’re doing and the studies you’re doing around amber light for stress reduction in students specifically. Are there other uses that you’re looking at related to light therapy?
Dr. Siminovitch: Yeah, it is a great emerging area. We all know seasonal effects and the effects of people sitting in front of bright devices who still don’t have enough light. Some people live in northern climates and sit in front of bright lights trying to train their circadian systems, but there are many arguments about how long you should do that.
Some people argue for very short periods, and some argue for very long periods. I think the stress mitigation, which we think is not hormonal, is perhaps something else happening instantaneously. We are looking at that.
There’s lots of very interesting work coming out on red light, and infrared light. Slightly different things. There’s stuff on infrared and also on far infrared that we don’t see that’s actually having an instantaneous and pretty profound effect. We are working with the University of British Colombia, and they have done some very interesting work on far infrared therapy.
We see this as the next big opening. Now, I have to say in the US, especially in California, we’ve done almost everything we can to eliminate red. Look at the glazing on windows, like low emissivity glazing. So we are cutting out a lot of red, so children inside schools aren’t getting as much red as they used to get. Light sources, especially fluorescent, were basically anemic, with almost no red content. Light sources outside of California are very anemic.
And, then think about incandescent. Incandescent has a lot of red in it, and a lot of red we don’t see. Unfortunately, people think that it’s an energy waste, but it also may be very important for us. There needs to be another examination of what is that infrared component doing for us. And it could be quite a lot.
So there is this whole new area of therapy that’s opening up to us.
Q: What are your recommendations for lighting adjustments for people with visual impairments, color blindness, or older adults who need more light to see clearly?
Dr. Siminovitch: So very simply, first we need a broad spectrum of light source. Particularly for the colored challenged individuals, including 10% of men that are listening to this. Turns out that 50% of all women are tetrachromats, meaning they have four broad color sensitivities because the information for red and green is carried on the X chromosome, and women because of genetic drift get two doses of that information.
There are people looking at this, and have said well, you know, girls are very good at fabrics, colors, textiles, and painting, and there may be a genetic predisposition that allows women to have broader color sensitivity.
Now, this is being looked at. But back to the question. First of all, we need rich broad spectrum distribution. The University of Davis California has adopted a 90 CRI specification, which means that we have a broad-spectral requirement. But outside of the university, everyone is starved for color, unfortunately.
And we need to change that. Certainly with our aging demographic, we need more light as we get older. This competes against the regulations we have for energy. We are constantly reducing power density requirements for lighting, which means reducing light levels.
For example, I am starting to wear glasses, I can’t read the newspaper anymore, and I struggle to read the back of the vitamin bottle. I wonder if I was ever able to do that, but we need more light. And it’s a very simple equation for more light equals better visual acuity, but really more light and what type of light for the aging population.
It turns out that with high color temperature or bright white light, you get a smaller pupil size, and with a smaller pupil size, you have higher visual acuity. As you get older, you get more junk in your eyes and you get this thing called blue light scattering, and you get more glare.
We need to be cognizant of these glare conditions, as older people often get misdiagnosed as being confused or unable to see, but maybe it is due to the lack of light and the glare, simple things like this.
So we are not cognizant of this, and we need to be. We need to do a better job of recognizing the requirements of the older population, and that maybe there are simple interventions we can be doing.
Q: What can be done for shift workers, especially night nurses, to improve their lighting environments?
Dr. Siminovitch: We have a project on this, and a big issue with night nurses. So if you think about night nurses, they are working at night, which is now their day. At night, the hospital light levels are coming down, lights are being turned off. Everybody’s going into sleep mode expect for the nurses who are working.
And if you go into nursing stations, many nursing stations at hospitals at night are very dark and it’s very subdued and respectful of patients, but the nurses aren’t getting enough circadian entrainment.
Much of the early circadian design and circadian research was built on high levels of problems associated with shift workers and nurses, which tend to have higher elevations of health problems. Part of that is due to the significant circadian disruption, so they need to have entrainment.
At UC Davis, we are looking at putting in daylight spectrum lights in their nursing station, so they will get bright white light separate from the patients. Basically like a sun room at nighttime, which is good for a homogeneous cohort. Unfortunately shift workers have a lot of strange schedule.
The second part of this problem, is shift workers typically go home to sleep during our day and they are confronted with lights, daylight pouring through the windows, and all kinds of disruptions that we don’t normally have at night.
So, I recommend to people who have shift work to have appropriate sleep architecture.
Look at things like blackout curtains to keep extraneous daylight from coming into your space. Overall shift workers can be supported through getting appropriate entrainment during the day and appropriate darkness at night. It’s about managing the environment, and Davis is starting to get in front of this, especially with our nursing stations.
Q: One last question for you before we close out the section. Section, you know that we’re building a new hospital, and I know that you’ve been involved in some of that. We’re trying to be more light sensitive, more enlightened. And, can you talk a little bit about that? The plans are. And the thought that is.
Dr. Siminovitch: Yes, we evolved the circadian protocol and we worked with the design team to provide recommendations for lighting in patient rooms, hallways, and the nursing stations.
A lot of our recommendations were approved, but you never get everything. But what we got have made some great steps forward. In patient rooms we were able to account for color change for daytime and nighttime, and then an amber layer for nighttime navigation, and some of that in the hallways.
For the nursing stations, we were looking at having entrainment capability. We think we will be able to implement most of these changes, with trade offs on cost. But most of these interventions are very low cost.
Also on stress mitigation, we are putting in amber lighting in standard MRI spaces at the radiology labs at UC Irvine. You know how terrifying an MRI is. And I am trying to push that forward at the hospital.
View Dr. Siminovitch’s full Wellness Academy Lecture for more illuminating lighting information.
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