Beyond Vision, the Future of Light and Health

Mariana Figueiro, Ph.D., light and health program director at the Lighting Research Center (LRC) and an award winning professor at Rensselear Polytechnic Institute, recently visited Dallas for the 2017 January Lightovation, where she presented research on the topic of light and health. During her visit, Dr. Figueiro also met with ALA staff to discuss her research and the potential for practical applications of this information in our industry.

Light and health research has been ongoing for some years now – since the 1970s at least. What are a few of the important things that have been learned?

We clearly know light is the main synchronizer for life on earth. We follow circadian rhythms, which are greatly influenced by exposure to light, and we know that people require bright days and dark nights. Our quality of sleep, cognitive abilities and overall wellbeing can be helped or hindered by the lighting in our environments.

The other thing that we know now, which we didn’t used to think a lot about when we considered lighting in homes or office spaces, is timing matters. The same light applied at different times of day is going to have a different effect on the circadian system. So keeping track of time and when you get light and when you do not becomes very important. We know we need to maintain a very regular light/dark pattern to maintain synchrony. If we lose that synchrony, we can be disrupted. It has been shown that circadian disruption is linked to a series of diseases. So we now know maintaining that regular light/dark pattern, called circadian entrainment, is very important for health and wellbeing.

We also know that the light characteristics for visibility are different than the light characteristics affecting the circadian system. Humans have a biological clock located in the suprachiasmatic nuclei of the brain that generates and regulates circadian rhythms. The circadian system is a blue sky detector. The peak sensitivity wavelength we normally use for calibrating our light meters for visibility is 555 nanometers (yellow-green), while for entrainment of the circadian system, 460 nanometers (blue) is where the peak sensitivity occurs.

Are we ready to turn these research findings into practical building and lighting design practice?

We still do not fully understand the pathways in the brain and the postprocessing interactions in the brain. So, we are still working on better understanding the effects of light.

We are still learning in terms of applications too, but I do think there are applications we are ready for. One application where I strongly believe we can make a positive difference is for aging and Alzheimer’s disease patients. Alzheimer’s patients are indoors all day, exposed to constant dim light. We have data, and others do as well, showing that if you provide a robust light / dark pattern for Alzheimer’s disease patients, you see a positive effect on their sleep, reduced symptoms of depression and reduced symptoms of agitation. I do not see the downside or any negative impact on these patients; therefore, I believe that is a very strong application.

Are there things in residential lighting people can start to consider implementing?

The first answer that comes to mind is daylight. No one is really afraid of daylight, so increasing the amount of daylight in the spaces where you are going to be, especially in the morning hours, is an easy way to start.

However, not everyone has access to daylight; one of the things I think is important is to increase the amount of light and increase the amount of short wavelength (blue) content in the sources that you are using early in the day. Honestly, light levels in the home tend to be extremely low; you’re talking maybe 50 to 80 lux at eye level. For the circadian system to be active, you’re probably talking 200 to 300 lux at eye level, so you want to add more fixtures – more lumens - into your living room, kitchen, etc., that will increase your amount of light exposure during the day. But, you also want to minimize that light in the evening. It is the combination of increasing in the morning and decreasing in the evening that helps maintain a healthy circadian cycle.

What types of lighting products do you foresee being developed related to light and health?

For residential lighting manufacturers, I am dying to see more creative plug-in luminaires. We tend to think about ceilings when considering lighting, but I think we are moving towards portable volumetric light. With edge lit LEDs and OLEDs, the opportunities for creating more illuminated flat surfaces without glare are expanding.

The other opportunity in residential lighting is connected lighting systems. One of the things we have been working on, which is very futuristic, deals with measuring photons of light. We know that you need to really be counting all the photons of light you’re receiving over the course of the day. Every person is different and will have a different biological clock and a different response to light. One idea is a sensor you could carry with you that measures the light you are receiving, and that would communicate with a hub in your house and change the lighting as needed. We have been working on some similar systems for other applications. The technology is here and we are doing the necessary research.

Are there any consumer-friendly resources or publications available that lighting retailers might use to learn more?

Yes, there are a variety of resources available at the LRC website (www.lrc.rpi.edu). I like to tell people these resources provide a toolbox, but it is up to them to look at the tool, decide who you are designing and installing the lighting for, and then apply some of these tools to different populations. It is not going to be a one-size-fits-all solution, but we have to start somewhere.

Additional Resources

Light and Health – LRC: www.lrc.rpi.edu/programs/lighthealth/index.asp

Light – Therapy for Better Sleep: sleepreviewmag.com/2015/05/lighttherapy-better-sleep/

TEDMED – Why an enlightened design integrates illumination