Full Spectrum Lighting – making the UV spectrum dance
The term full-spectrum was coined in the 1960s by photo biologist Dr. John Ott to describe electric light sources that simulate the visible and ultraviolet (UV) spectrum of natural light. There are now dozens of electric lighting products marketed as full spectrum lighting, some promising that they closely simulate daylight and can therefore provide benefits such as better visibility, improved health, and greater productivity.
Different companies have different ideas about what constitutes a full spectrum lighting source, and what it is about full spectrum light that yields the claimed benefits. Some insist that invisible-to-the-eye UV radiation is a necessary ingredient in full spectrum light. Recently, several lighting products have emerged that reduce radiation in a small part of the visible spectrum in an effort to improve visibility—and these products are also called full-spectrum.
Benefits of full spectrum lighting
Full spectrum lighting or “day light stimulated illumination” has several benefits as follows:
1. Psychological
Most people prefer daylight from windows and skylights to electric light. Daylight gives people a positive feeling and can help improve mood and motivation. Because “full spectrum” light bulbs produce the appearance of white or bluish-white light and because they also produce a higher perception of brightness, there is often a positive association with daylight.
2. Health
Full spectrum light therapy is sometimes recommended for people suffering from seasonal affective disorder (SAD). Research shows that any light source (preferably daylight) at 10,000 lux (1000 foot-candles) aimed toward the eye for 30 minutes a day, can be effective. Light sources with a strong blue wavelength component are most effective. “Full spectrum lighting” usually meet this standard. Any electric light bulb with a “color temperature” of 5000K or higher also meets this standard.
3. Color
Daylight provides the highest level of accurate color representation. Most incandescent and halogen light bulbs produce light that is excellent at color representation. However, they usually do not also produce the bluish white light associated with daylight. “Full spectrum” light sources, usually fluorescent, often attempt to provide both excellent color rendering and light that appears similar to daylight.
The lighting industry uses a value called the Color Rendering Index (CRI) to describe the ability of a light source to render colors. The higher the number, on a scale up to 100, the better the light source for accurate color rendering. By definition, daylight and incandescent light sources have a CRI of 100. Many light bulbs marketed as “full spectrum” have a CRI of 90 or higher. When color identification is important such as in graphic arts, museums, color printing and the fabric industry, high CRI illumination is beneficial.