The Circadian System: Aligning the Body’s Internal Clock

Interview by Gayathri Unnikrishnan
Sep 29, 2017 10:05 AM ET

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Robert Soler is Vice President of Human Biological Technologies and Research at Biological Innovation and Optimization Systems (BIOS). Prior to his work with BIOS, he worked with the Kennedy Space Center, where he was integral in the development of the first LED light used on the International Space Station (ISS), and was subject matter expert on a lighting system designed to synchronize circadian rhythms of astronauts aboard ISS. Robert spoke with us about how his work as a lighting expert has inspired everything from innovation in outer space to the synchronization of his children’s bedtime routines.

What first inspired you to join the lighting field?

I've always had a respect for light. When I was getting my undergraduate degree in electrical engineering, Cal Poly had a minor program in lighting and I found it fascinating. Once I was exposed to some of the fundamental impacts light has on organisms and biological systems, I became even more passionate and entered the Master’s program at the LRC.

What was it like to be a lighting expert at the Kennedy Space Center?

I worked at the Space Life Sciences Lab, and there was a lot of really cool research going on. One of the most dynamic areas of collaboration and research was focused on Mars exploration, where everyone was an expert in a one specific field or another. It was a great place to start a career because lighting played such an integral role in the work of so many different fields. I worked with microbiologists who were interested in light's interaction with bacteria, as well as plant researchers who wanted to understand different wavelengths of light. Still others were interested in how light interacts with astronauts’ circadian rhythms, and that’s where I really wanted to have an impact. It was exciting to work with so many people who were experts in their individual fields and show them how the application of light could really impact their theories and results. I was able to get broad experience and facilitate a lot of the research. In each of those studies, the spectrum of LED lighting was a key component to the outcomes we observed.

Can you tell us about how you developed lighting systems to synchronize circadian rhythms of astronauts aboard the International Space Station?

What we understand about circadian rhythms is it's a 24 hour biological cycle synchronized to the 24 hour cycle of the sun. But since the space station orbits the earth every 90 minutes, providing a sunrise and sunset every 45 minutes, our human bodies don't know how to process that kind of unnatural, acclelerated cycle. Because of this our bodies start depending on an individualized free-running clock, which is close to 24 hours but not exactly 24 hours. Mine might be 24.1, yours might be 24.2, someone else’s might be 23.9 and although these differences are very small, that's just day 1. So after 10 days it's a 60 minute difference, and after 100 days it becomes 600 minute differences. When we designed the lighting for the international space station, the idea was to be able to give a strong enough cue so that everyone could synchronize to a true 24-hour cycle, and therefore be able to work effectively and safely together in a very dangerous environment.

Why is the circadian system so important to human health and well-being?

The most obvious thing the circadian system impacts is our sleep cycle and our alerting profile.

But what's not very obvious is that a master clock controls the majority of our physiology directly or indirectly. There are peaks and troughs to a lot of biological processes, like our hormone secretions and our enzyme activities.

In fact, there’s a whole emerging field called chronotherapy, which explores not just what medicine to take but what time to take it. We have found our bodies utilize medicine differently depending on when it’s administered, and by studying its link to our circadian system, we can actually increase a medication’s overall effectiveness. We are finding that our inner clock is very pervasive throughout our bodies, when we desynchronize things by not having a robust light cue, chaos can ensue. Alternatively, when we are able to supply this robust light cue, we can synchronize our systems and mitigate a lot of issues caused by our artificially illuminated society.

How can we use technology to help maintain our circadian health?

We now understand that a newly discovered photoreception system mediates how our circadian rhythms synchronize to light each day. This is interesting because it’s different from vision, and thus we can isolate this daytime signal from vision, such that we can use lights with a high daytime (melanopic) signal during the daytime and a low daytime (melanopic) signal at night to help improve our circadian health. However, there are other things like television screens, cellphones and tablets that can interrupt our natural cycles. Luckily we also have technology that works to correct these interruptions. You can remove the blue component on your screens at a specific time through systems like f.lux, which is available free for the computer, and through other programs like the Twilight app and Night Shift for Apple.

Interestingly, the impact of light at night, which gains a lot of attention, is magnified by the fact that we do not get enough light during the daytime. At BIOS, we understand this, and thus created a spectral solution with a heightened daytime signal for places we are during the daytime, such as offices and schools. Moreover, we’ve figured out a way to get high amounts of this daytime signal without compromising color preferences.

What advice would you give people who want to align their circadian systems to the natural daylight cycle - one or two simple things that people could follow to align their circadian systems to the societal cycle?

While lighting cues can be your primary signals, behavior also plays a central role in circadian alignment. We can automate lighting strategies, but people still have to understand that there are certain times they shouldn't be out. You shouldn't be at the gym at midnight if you're trying to go to sleep at 1 o’clock in the morning. There’s a lot we can do to improve our circadian health with lights, colors, cues, and external factors, but most of it comes down to our behavior and habits.

In my house, a timer switches the lights in our house from high daytime signal to low daytime signal automatically according to our routine. This switch changes both the intensity and the spectrum of light (not the color of light). The way I see it, what goes on outside, from the solar cycle doesn't impact our social requirements: when my kids need to go to school, what time they should be going to bed to get enough sleep, what time my work schedule is. As a result, we've honed in on a lighting routine that keeps us on a social time cue rather than a solar time cue.

To learn more about how light impacts health and strategies for designing spaces that can help align with the body’s natural circadian rhythms, download the Light WELLography available on our new WELL app, Build WELL.