Light from the sun supplies the energy needed by every living thing on earth. Amazingly, there is still ongoing debate about what precisely sunlight and other sources are made of. Is it a wave? Or a particle? Or both? Surely it would be reasonable to say that light is a nutrient that is just as important to health as air, water, and food. Poor quality light may be just as harmful as poor-quality food, water, or air.

Most of the lighting in homes, schools, stores, and business locations is of poor quality. Most manufactured lighting causes irritability in students, lower production amongst workers, reduced absorption of calcium(leading to brittle bones), and can contribute to Seasonal Affective Disorder(SAD) and the more common, "winter blues".

Light from the sun is 'full-spectrum'. Normal light bulbs and fluorescent tubes are not - they produce an overabundance of light in the yellow and orange spectrum. The glare from typical artificial light sources is irritating. Artificial light can make people sluggish and more prone to error. Recent improvements in technology have allowed for the manufacture of good-quality artificial light using full-spectrum fluorescent and high-spectrum bulbs.

How Does It Work?

There are two primary factors in the rating of full-spectrum lighting. The first in Color Rendering Index(CRI), and the second is Kelvin Heat Rating. CRI designates the proportions of each color contained in the light. Natural outdoor light has a CRI of 100 and a Kelvin rating of 7500 degrees Kelvin. In the lighting industry, 5000 degrees Kelvin and 90 CRI(or higher) is considered full spectrum. Standard cool white fluorescent tubes have a CRI of 68; warm white fluorescent is 56 CRI, and standard incandescent bulbs have a CRI of 40.

Under natural light, or full-spectrum that adequately duplicates natural light, people feel better overall. When you have better visual acuity, you can work more productively, with less error and fatigue. When Data Control Company of Kansas City, USA, redesigned their facility using full spectrum light they experienced an annual savings of $235,000 because of reduced errors in data entry by employees. When the US Postal service fitted its Reno, NV, facility with full spectrum lighting, their energy savings were immediately $50,000 per year. But what they did not expect was that postal worker productivity rose so quickly and so greatly that they estimated that improved productivity alone was worth nearly $500,000 per year, $200,000 more than the cost of the new lights in that sprawling facility.

A well-documented study by Pacific Gas and Electric Company demonstrated that there is a distinct correlation between occupant productivity and daylighted buildings. The study demonstrated increased retail sales(average 40%) and better school test performance(typically 10-20%) when occupants were exposed to daylight. The study examined 3 different school districts in California, Washington State, and Colorado. Even though climate, building design, curriculum, and teaching methods differed widely, the results from daylighted rooms were consistant. For the retail sales study, 108 stores operated by a chain retailer were examined. The design and operation of the stores was nearly identical, with the exception that two-thirds of the stores had sky-lights, and one-third did not. Skylights boosted sales by almost 40%.

What About Seasonal Affective Disorder?

Many people feel mildly depressed at times during winter months, but some people have more severe symptoms: feeling down all the time, low energy day-after-day, problems with sleep and appetite, difficulty functioning at work or even in the home. When these symptoms occur during the autumn and winter season and typically go away in the spring, it is often called Seasonal Affective Disorder(SAD). As many as 35 million Americans may suffer from SAD, with a much greater concentration living in Northern sections of the country. Light therapy, also called photo-therapy, can help 60 to 80% of SAD sufferers. As little as 30 minutes per day sitting near a "light box" can result in significant improvements. Some report dramatic improvements in attitude, energy, and sleep patterns after as few as 3 or 4 days of daily exposure to this strong light source.

There are several overlapping theories as to how light therapy helps victims of SAD, but in August of 2001, Neuroscientists at Jefferson Medical College clarified that wavelengths of blue light had the highest potential to cause changes in melatonin levels in the blood. Melatonin is believed to be a key regulator of circadian rhythms, or biological clock.

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