Impact of Light on Human Health and Welfare

Light is fascinating. Its ability to impact us, intimidating. Our dependence upon it, total. Light affects our moods, our physical state, and by extension, our health. Chronobiology is a relatively new science that studies just that; the impact that light has upon our physical and mental health. The purpose of this new field of study is to discover and develop design solutions that fuel health and performance.

            Within the past decade and a half, scientists have discovered a new receptor cell that resides within the human eye, called ganglion cells. These cells track minor light changes and are what trigger our daily circadian rhythms as well as our seasonal reactions to light. These rhythms affect almost all other systems of the human body. Our bodies rely so heavily on these cues to function, that when we are not exposed to the normal levels of light (particularly daylight) that our bodies need, our health can be affected. This is called SAD, Seasonal Affective Disorder. The results of this condition can be a weakened immune system and diminished endocrine (the system that manages hormone production) functions. It can also lead to larger problems like diabetes, growth problems, weight gain, reproductive problems, and premature aging. Increased cancer rates have also been found to be a result of SAD. The shift in circadian rhythm due to the overexposure of light has even been determined to be a strong contributing factor to breast cancer.

            Everything revolves around light. The earth revolves around the sun, which creates our days, which creates our circadian rhythm (our internal clock), which we now know our health depends on. About ten percent of our genes are regulated by light. Light is important! Lack of light causes our bodies to produce melatonin. Melatonin is a chemical, released by the endocrine system, which allows your body to feel tired and go to sleep. It also works the opposite way. More exposure to light prevents or puts off the production of melatonin. Scientists are now finding that over exposure to light, after the sun has gone down, throws off the production of melatonin, which throws off your circadian rhythm, which throws off your sleep cycle, which, scientists are now finding, can contribute to a variety of diseases.

            Although artificial light has been around for over a century, these problems are just now coming to the surface. This is largely because traditional artificial light produced light on the red side of the spectrum, modern light, LEDs and fluorescents, produce light on the blue side of the visible spectrum. Scientists have discovered that light on the blue side of the spectrum slows the production of melatonin more readily then light that is on the red side of the spectrum. As a result, blue light keeps us more aware and awake than red light but interrupts our body’s natural rhythm more. Exposure to even normal household light, late in the evening, can postpone the release of melatonin for up to an hour and a half after exposure.

            Light is vital. It is how we organize our days, our lives, our society, and our world. Disrupting that with overexposure to artificial light and inadequate exposure to natural light can be detrimental in terms of immediate and long term health. 

Works Cited:

1.     Edelstein, E. (2009). Influence of Architectural Lighting on Health. InformeDesign Newsletter, 7 (2), 1-5.

2.      Beil, L. (2011). In Eyes, a Clock Calibrated by Wavelengths of Light. New York Times. June 4. Retrieved from http://www.nytimes.com/2011/07/05/health/05light.html?_r=1&pagewanted=print