Natural and Circadian Lighting
There is perhaps no element in our existence that affects us as strongly as light. Throughout time, our lives have been shaped by the rising of the sun and reflective light of the moon and stars. Light as a representation of divinity is a concept that runs through every major religion symbolizing wisdom, knowledge and the divine presence.
However, in our modern world we often take light for granted and are overwhelmed by it. Terms like “light pollution” are commonplace preventing us from seeing the stars. We also spend 90% of our time indoors, mostly in buildings with static, artificial light and little or no natural daylight.
Concerns like these are often written off as nostalgic folly, but is it possible that the way we use light can seriously affect our health and our emotions? Should buildings be designed with more care to the essential connection we have with natural light and its rhythms?
Light affects our circadian rhythms more powerfully than any drug.Charles Czeisler, Harvard Medical School
The cycle of daylight’s effect on our bodies is known as a circadian rhythm. Scientific and medical research has solidly confirmed that disturbances in our circadian rhythms can lead to sleep deprivation and serious problems such as accidents, depression, cancer and cardiac disorders.1
Natural morning daylight is rich in blue light which gets us going, and the absence of blue light in the evening releases the hormone melatonin making us sleepy. An important neurotransmitter known as serotonin, which impacts every part of our bodies from our digestive systems to our emotions and motor skills, is also controlled by blue light.2
As Salk Institute researcher, Satchin Panda, explains, “Almost every gene in our genome turns on and off at different times of the day. Every single hormone and brain chemical also rise and fall at different times of the day. So, to have these rhythms is actually to have health.”3
Blue light is not delivered to the part of the brain where our visual images are formed. It is instead channeled by a protein in our eyes called melanopsin to a region that is only responsible for controlling our circadian rhythms. This light is therefore different than the kind of light we need to see well. Even those who cannot see can process blue light.
Avoiding disruptions in the circadian rhythm is crucial and especially important for children. Their eyes are more sensitive to light and since their brains and bodies are in a stage of development, it is critical that their circadian rhythms stay in natural sync.4 Typical home lighting can cause a 50% suppression of melatonin in the evenings. Even a dimmed light can delay the onset of melatonin in sensitive individuals.5In addition, the use of smart phones, tablets and computer monitors in the evening can further disrupt the circadian cycle when used in daylight mode with blue light.
Interior lighting for wellness
The power of designing with natural daylight has been intuitively known by designers, architects and builders for millennia. There are many design solutions to bring indirect or diffused natural daylight into a building. Northern light, light-diffusing filters, or reflection from textured surfaces are all tools of top designers and architects. They know how to take advantage of corridors, stairwells, structural intersections and interior gardens.
Mary Guzowski who has researched daylighting masters such as Louis Kahn and Tadoa Ando notes, “Daylight and the changing environmental forces of sun, wind, and weather help us to know “where we are” and “who we are” by rooting us in the ecological phenomena of a particular place, in that climate, and on that site. When coupled with passive solar and bioclimatic design strategies, daylight can reduce energy consumption and provide environmental benefits while enhancing human comfort, health, and well-being.”6
Interior circadian lighting
The idea behind interior circadian lighting is that it will keep the indoor atmosphere lit at the same intensity and color as outside. Simulating natural conditions, it allows our melatonin to be released around 9:00 pm and stay in our system until 9:00 am.7
Although the technology behind circadian lighting is relatively new, a lot of research is taking place now that is helping lighting designers to narrow in on the technical specifications needed to produce circadian stimulus. In their research, Rensselaer Polytechnic Institute found that using saturated blue-light LED’s in vertical interior, glass partitions in the morning boosted the circadian stimulus of participants in their study. For the post lunch dip in energy, a red luminous partition provided an alerting effect like a cup of coffee.8
The use of orange lights in the early evening, which mimic the color of the evening sky, also help our bodies to start producing melatonin. The latest software versions on smart phones and tablets are now offering a night mode which reduces the blue light by shifting to a warmer orange light, and there are monitors on the market which automatically transition to orange light in the evening.
Although this new lighting is very helpful, it cannot replace natural light entirely. In a study done in 2014 by Antal Haans, participants knew the difference every time between natural and artificial light regardless of the presentation.9 Therefore, natural light should still provide the basis of any lighting design.
The power of light
As Louis Kahn observed, “To the musician a sheet of music is seeing from what he hears. A plan of a building should read like a harmony of spaces in light. Even a space intended to be dark should have just enough light from some mysterious opening to tell us how dark it really is. Each space must be defined by its structure and the character of its natural light.”6
Saharchitects is experienced in understanding how to design with the natural environment. If you are considering renovating or building a new home, please contact or follow Saharchitects to learn more.
- Health Risks Associated with Genetic Alterations in Internal Clock System by External Factors, Khan et al, International Journal of Biological Sciences, May 2018.
- Serotonin: What You Need To Know, Annamarya Scaccia, Healthline Magazine, May 2017.
- Eating in 10-hour Window Can Override Disease-Causing Genetic Defects, Nurture Health, Chaix & Panda et al, Salk Institute, August 2018.
- Children Uniquely Vulnerable to Sleep Disruption from Electronic Screens, University of Colorado Boulder, November 2017.
- High sensitivity and interindividual variability in the response of the human circadian system to evening light, Phillips et al, PNAS, June 2019.
- How the Masters See It: Six Ways to Design with Light, Mary Guzowski, ArchDaily, July 2018.
- Melatonin and Sleep, National Sleep Foundation, https://www.sleepfoundation.org/articles/melatonin-and-sleep, 2019
- Designing with Circadian Stimulus, Lighting Research Center Rensselaer Polytechnic Institute, LD+A Magazine, October 2016.
- The Natural Preference in People’s Appraisal of Light, Antal Haans, Journal of Environmental Psychology, September 2014.