A breakthrough in the research on the impact of light on our well-being has revolutionized efforts to create optimal indoor lighting conditions.
According to Joachim Stormly Hansen, an expert in optical indoor climate at Grontmij/Carl Bro, research on light is still in its infancy, but the potential is enormous. Daylight is crucial for human well-being, and there are ambitious efforts to replicate nature's lighting conditions. However, this task is far from simple.
The popular explanation
In a larger perspective, artificial electric light has only existed for a surprisingly short period in human history – and it doesn't align with our biological circadian rhythm.
— Since the first humans lived on the savannah in Africa, daylight has defined our circadian rhythm. Humans spent their days outdoors and only sought shelter in their caves when it got dark. Simply put, our system is designed to derive energy from a balance between light and darkness, and daylight plays a central role in this. When the balance is disrupted, it affects our well-being - it's as simple as that, explains Joachim Stormly Hansen.
— The more complicated aspect is that daylight affects our circadian rhythm in several ways, such as our sleep, wakefulness, body temperature, and overall well-being. All areas where traditional electric lighting usually falls short. When our circadian rhythm is disturbed, we react. A tangible example is the discomfort of jet lag. We become unfocused, disoriented, tired without being able to sleep. It's our body's natural rhythm that gets shifted - and we become less effective and alert. The same goes for people exposed to night shifts or those who work in darkness throughout the workday. That's why there is a great interest in developing even better artificial light that can cater to our natural circadian rhythm as a substitute for the properties of daylight, he continues.
The scientific explanation
In 2002, there was a groundbreaking discovery in research regarding our dependency on daylight for our circadian rhythm.
— It was David Berson who first uncovered the light sensitivity of a subgroup of retinal ganglion cells found in the layers of the retina. These ganglion cells contain a light-sensitive substance called melanopsin, which sends signals to and regulates the brain's internal clock based on the intensity, color temperature, timing, and spectral composition of light in our surroundings, explains Joachim Stormly Hansen.
Our internal clock then sends signals to other parts of the central nervous system, activating various hormones such as cortisol, which keeps us awake, melatonin, which makes us sleepy, and serotonin, which regulates our mood. It has been shown that melatonin, for example, is naturally secreted when it gets dark. Production increases from the beginning of darkness until midnight, and production is highest in winter, provided our circadian rhythm is not disrupted. Cortisol also has a rhythm with high levels in the morning hours, and that is what makes us active. What's interesting is that traditional electric light can only cater to our visual conditions, but it is not capable of replacing daylight in terms of influencing our circadian rhythm. The circadian-regulating hormones are sensitive to light in the blue part of the color spectrum, ideally around 480 nanometers and with an intensity of 1000-1500 lux on the eye or higher.
— Traditional electric lighting in offices is typically projected between 200 and 500 lux - so there is still a long way to go. In comparison, the artificial light used for so-called light therapy lamps is between 5000 and 10,000 lux, and there is increasing attention in this area. Research is in full swing, and many attempts have been made to recreate artificial circadian rhythm light but the real thing, daylight, is still the best, emphasizes Joachim Stormly Hansen.
High commercial interest in artificial circadian lighting
Not all of us have the luxury of sitting near a window at our workplace. Many employees find themselves spending their entire day away from natural daylight, whether it be in large production halls, stores, shopping malls, or operating rooms. It's understandable that there is a great interest in creating a lighting solution that caters to our circadian rhythm. However, it's important to note that there are currently no solutions that can fully replicate the benefits of natural daylight in terms of overall well-being.
In my work with optical indoor climate, I focus on various factors that can enhance people's well-being in future buildings. With the new knowledge we have gained, it is evident that light is a crucial element in creating a sense of well-being.
— Joachim Stormly Hansen, an expert in the field.
There are several examples of artificial circadian rhythm lighting available on the market, and this area receives significant attention from the industry.
— Ongoing research, such as that conducted by the Society of Light Treatments and Biological Rhythms (SLTBR), in which I participate, continues to shed light on exciting new perspectives. For instance, it has been observed that older eyes are less receptive to light's hormonal effects, and Alzheimer's patients often suffer from disruptions in their circadian rhythm. Additionally, there are differences in how individuals with different sleep patterns are affected by circadian lighting. It will be fascinating to hear the latest research findings in the field of lighting when SLTBR members gather in Berlin in June, concludes Joachim Stormly Hansen.