Light is at the foundation of life on earth. Humans are also fully adapted to function and perform in light. As they say at a well-known outdoor store, “not everyone is an outdoorsman, but no one is an indoorsman.” Throughout most of mankind’s existence, man has been primarily concerned with functioning and performing during the day. At night, humans sleep to recover from the day and prepare for the day ahead. Sunlight has been the crucial element, and this is what humans have been completely attuned to. With different eye receptors and light sensitivity, sunlight determined human perception, circadian rhythm and overall health. Light quality is therefore critical to performance.
For several hundred years, many people’s lives have largely taken place indoors. Dark rooms provided with artificial lighting. Where the human eye has adapted to light intensities of 1,000 lux (cloudy day) to 100,000 lux (bright summer day around the equator), indoors the light intensities are not even close to 1,000 lux. An average office will match a light level somewhere between 300 lux and 600 lux. The light quality of artificial light generally does not remotely match the spectrum of sunlight. Different biological processes are driven by different wavelengths, and the diversity in wavelengths is predictive of the contrast effect of perception. For Clearlight, light quality means the presence of the various wavelengths in sufficient quantity and in the right proportions of each other.
The spectrum is usually measured and determined according to the CRI index.
Want to know more about CRI, Blackbody locus, TM-30-15 and CQS?
Human eyes basically see 3 colors: red, green and blue. All other colors are formed based on these 3 colors. Or conversely, the lack of one of the colors creates contrast causing perception. This is a process in which the visual receptors (eyes) cooperate with the brain. It allows people to act in the environment.
In sunlight, the amount of light and contrast determine how sharp our perception is. Sunlight is basically the best quality of light and thus a kind of gold standard. However, this is different for each person. The older we get the higher the light level needs to be to make the same quality observation. This includes situational factors but also, for example, how rested a person is.
The moment when the eyes refocus based on the distance to an object is called accommodation. The bulge of the eye changes and with it the focal length, which sharpens, or does not sharpen, the perception of the object. The moment the light quality is insufficient, greater demands are made on the accommodation muscle. After all, the perception is not optimal so extra focus is needed to achieve a detailed observation. The extra effort causes extra strain on the accommodation muscle. An overstrained accommodation muscle can bring a wide range of health complaints. Good lighting quality reduces or prevents the negative effects mentioned above.
Different wavelengths have different biological effects. Take, for example, the third photo-receptor in the mammalian eye[1]“. These photo-receptors provide an ideal sleep-wake rhythm based on the seasons. To keep the sleep-wake rhythm in line with darkness and light, the aforementioned photo-receptors register the amount and composition of light. Certain wavelengths here trigger certain responses that contribute to hormonal balance, think melatonin, testosterone and cortisol. Thus, the sleep-wake rhythm is kept in line with daylight hours as much as possible.
Short wavelengths here have a more dominant role in supporting the waking pattern, with longer wavelengths supporting the sleeping pattern.
Despite the fact that light is at the basis of life, light and its effects and processes are still largely new to science. The amount of research currently being done on light, light quality and the effects of light on health, nature and people is immense.
Interesting new results from research also underscore the importance of non-visible light for eye health[1].
“Whenever possible, daily direct exposure to sunlight in the morning is recommended. Consider a walk outside, or grab a meeting in the sun.”
Looking for lighting with a good light? Then check out our ClearLED daylight lighting
