We are light beings, our biology is entrained by light, and our psycho-physiology is profoundly affected by light. We have evolved in this planet under the direct influence of daylight proceeding from the Sun, our closest star, and by the darkness of the night.
Day and night are the consequence of the Earth rotating around its own axis, and seasons are the result of the rotation of the Earth around the Sun. Our biology is organized under the rhythmicity of the Sun, and our visual system has evolved under the light rhythmicity of the Sun.
Almost two thirds of our brain power during our physical awakened activity is taken by our visual system signaling, by far the most demanding system to our upper brain. This is how we have been conceived as human beings.
In modern societies we spend around ninety percent (90%) of our time indoors, under the influence of artificial light, that is not only electric light. The natural light passing through glazing loses some properties from the direct sunlight such as ultraviolet (UV) and infrared (IR), and glazing reduces considerably the intensity of the sun radiation. Indoor daylight is quite acceptable for our visual system, due to its balanced spectrum. Traditional electric light, particularly fluorescent and LED fake the light spectra emission to produce the white perception, and our subconscious visual system recognizes the fake, besides the fact that our biology does not understand about color, that is an elaborated perception. Our biology understands of spectral power distribution.
Since the discovery of the third photoreceptor of the eyes, the intrinsically photosensitive retinal ganglion cells (ipRGC), white light for vision is not anymore white for the visual system. These photoreceptors regulate several functions of our essence. First the pupillary light reflex, already discovered by the Scottish physician Dr Robert Whytt (1714–1766) in the 18th century. Second the circadian regulation of our bodies through light, discovered no more than twenty years ago. And finally, the influence of light in eye health, with recent discoveries about the potential influence in visual alterations such as myopia.
The discovery of this third photoreceptor, the field of lighting has dramatically changed and we can no longer ignore that traditional methodologies and metric are not valid anymore. This photoreceptor has promoted the science of human centric lighting (HCL).
We have introduced the Human Centric Lighting (HCL) topic in the last nine (9) issues of the magazine. This September issue has its main focus around this challenging and amazing field.
I would like to take the opportunity to summarize the HCL knowledge that we have shared. Before summarizing our journey, I am very proud of having three rare and unique colleagues contributing to this special issue.
Richard Vincent, an architect at Mount Sinai Hospital in NYC, Anadi Martel, a physician and a exceptional person and researcher and the former president of the International Light Association (ILA), and Dr. Stephen Mason, a unique optometrist concerned with the effects of light and lighting in the human visual system beyond the visual function.
After the introduction of my colleagues, that have contributed to this issue of the magazine, lets summarize now the journey that we started nine months ago in this amazing and challenging field of human centric lighting. The topics that we have introduced are: human centric lighting definition, the healthcare environment, the WELL Building Standard, Sleep Hygiene, Ethics, White Full Spectrum, Farasdues / An Spiritual implementation, the Exposome and Visual Health I.