• Courtney Van Ostran, CPSM

Did you know that Light has a key effect on your Circadian Rhythm?



Do you know everyone is born with rhythm? Not always musical rhythm but Circadian Rhythm, this is your internal 24- hour clock that is responsible for managing many of your body’s biological functions. Originating in the area of the brain called the hypothalamus, it functions by receiving signals from your eyes that indicate when it is daytime and nighttime. The hypothalamus in turn controls the amount of melatonin released to correlate sleepiness with darkness and alertness with lightness.


Research has indicated that Light affects both our visual and non-visual systems and electric light has a key effect on our Circadian Rhythm.


What is the first thing you notice when you step into a new building? For some, it might be the temperature of the space, whether it is too hot, too cold, or exactly right. For others, it could be the art on the wall, or the materials used to give the building unique characteristics. However, one of the most important aspects of a great building is the way it is illuminated; believe it or not, lighting has a direct impact on an individual’s health and comfort due to the regulation of various biological functions.


According to the International WELL Building Institute, these functions include the endocrine, digestive, nervous, muscular, immune, and cardiovascular systems, as the human brain regulates physiological rhythms throughout the body’s tissues and organs.


In effect, this rhythm plays a big role in hormone levels, in addition to sleep-wake cycles. According to the Sleep Foundation, circadian rhythms play a strong role in the human body’s ability to sleep at night and allow for wakefulness throughout the day. When our circadian rhythms are disrupted, health risks including Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, and Irregular Sleep-Wake Rhythm Disorder (among other issues) can occur.


An individual’s exposure to different kinds of lighting plays a large role in this phenomenon. The intent of circadian lighting design is to utilize a facility’s lighting to align with our internal body clock, but oftentimes, that’s easier said than done.


As Terry Kilbourne, CEO of Tec Inc. Engineering & Design points out, “Minimizing exposure to blue wavelength light is beneficial at night prior to bedtime; however, many of us spend the last few hours before going to sleep on our cell phones, iPads, or watching our favorite television program. All these electronic devices emit a high level of blue light at a time when we should be minimizing our exposure. It is no wonder our body is confused.”


In general terms, the ideal light for our biological rhythm comes from the daylight produced by the sun, that’s without exception. Unfortunately, in order to take care of our daily business, many humans spend a majority of their day in the confines of their office. Therefore, most of the population is experiencing under-lit spaces that aren’t doing our circadian rhythm any favors.


In an interview with Architect Magazine, Mariana Figueiro, PhD, director of the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute, said, “Due to restrictive energy codes, daytime light levels in buildings are often too low or at threshold for activating the circadian system. Even in open offices with many, large windows, workers do not receive enough daylight to stimulate their circadian system, due to factors such as season, cloud cover, desk orientation, and window shade position.”


While manufacturers may label certain ‘tunable’ lighting options as ‘circadian’, they do not truly meet the ideals of a circadian system, as their tuning methods can cause eye fatigue and glare if not properly implemented.


However, the addition of LED paneling can be a great way to resolve circadian lighting objectives. In Arup Journal, a case study was conducted, revealing that one well-designed LED lighting system at the Kaiser Permanente Medical Center in San Diego, CA had a direct effect on patient recovery. The more comfortable lighting scheme allowed patients to sleep better in the often-uncomfortable hospital bed setting. By implementing “cooler” blue wavelength light during the day to promote wakefulness and “warmer” red wavelength light during the evening hours to promote restfulness, patients receive a more comfortable recovery time.


How can circadian lighting be implemented in your building?


With the rise of health trends in the industry, electrical engineers and lighting designers alike are becoming increasingly interested in circadian lighting as an option for their clients.


“One of the challenges implementing appropriate circadian rhythm friendly illumination is being able to balance increased illumination intensity with restrictive energy code requirements, the capital cost of lighting control systems, and the overall personal increased productivity and well-being,” adds Mr. Kilbourne.


However, different spaces call for different lighting requirements and needs. “The important thing about circadian lighting is that it’s really a 24-hour light-dark pattern,” Dr. Figueiro said in an interview with The New York Times. “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.”


Compensating for these different environments is key. According to the Center for Disease Control, circadian clocks are at their most-sensitive from two hours before a person’s usual bedtime, through the night, and then until roughly one hour after an individual wakes up. In other words, having a knowledge of a given space’s occupants throughout the day and compensating for their sleep-wake cycle is an important element of determining the best way to plan a circadian lighting layout.


All spaces are different and need to be examined closely for the best way to mix incoming sunlight and the space that needs to be illuminated. This requires closer examination from a lighting designer experienced in circadian concepts.


At Tec Inc. Engineering & Design, we’re studying these trends as they evolve. In recent years, Brandon Sargent, PE, LEED AP BD+C and Associate of the firm, has continually researched these solutions and discussed it with our clients explaining how it could be of benefit to their space. While it’s important to compare the overall cost to the project with the benefits it can provide; he will help you determine if circadian lighting would be applicable to your space and occupants.