Light Box Full Spectrum Controversy : Apollo Health

When bright light was discovered to treat Winter Blues and other circadian rhythm problems, most people believed that since the lack of sunlight was causing the problems, the obvious answer was to replicate sunlight as closely as possible. Several studies touted the benefits of full-spectrum light on health, student and worker improvement, alertness and performance.

Harmful Effects of Standard Fluorescent Lighting

Few doubt the advantages of newer lighting technology over standard fluorescent lighting developed decades ago. Standard technology's focus was on efficiency-how to produce the most light for the least cost. The problem was that this technology produced lighting with a green or purplish hue. Worse yet, the cheaper magnetic ballasts cycle at a frequency which is perceptible by the brain, and caused many people to become sick or nauseated. Those prone to epileptic seizures were more susceptible when in this light, and some people would get migraine headaches. In Europe, Germany went so far as to ban cool-white fluorescent lights from government offices.

The Full-Spectrum Bandwagon

As the term 'full-spectrum' caught on, more and more people were drawn to products that offered full-spectrum lighting. Industry catchwords such as Kelvin Temperature and Color Rendering Index (CRI) became the new standards for measuring light. In general, Kelvin temperature ratings of 5000° or higher and CRI of 90 or higher denoted a truer, full-spectrum light.

What is Kelvin Temperature?

Kelvin Temperature indicates a specific hue or color of a light source. Scientist William Kelvin developed this temperature rating scale in the late 1800's. Kelvin took a cube of black carbon, heated it and recorded the color hue at certain temperatures. 0° Kelvin is pure black while 8,000 - 10,000° Kelvin represents a cloudy day. 5,000 - 5,500° Kelvin represents noonday sunlight. 2,500 - 3,000°K represent normal, indoor tungsten lighting, and 3,200° represents standard fluorescent lighting.

What is Color Rendering Index (CRI)?

The Color Rendering Index is a scale (100) that represents how closely a light source depicts or reflects an object's true color. As a general rule of thumb, the higher the CRI, the more accurate an object will appear. In the lighting industry, a CRI of 85 or higher depicts a truer color.

Jumping to Conclusions?

Although many studies showed the benefit of full-spectrum light, these studies did not control for full-spectrum vs. broad-spectrum lighting. In fact, those studies comparing full-spectrum with broad-spectrum non-UV light showed both worked with equal efficacy. After many years, light therapy researchers at the Society for Light and Biological Rhythms (SLTBR) concluded that the relationship between health and light may have more to do with intensity and volume of light than with full-spectrum. Indeed, low-level full-spectrum light studies showed no improvement over normal conditions.

How Accurate are Kelvin and CRI in Light Therapy?

A higher Kelvin Temperature or CRI does not equate with higher effectiveness. Kelvin Temperature and CRI have never been used in any light therapy study to determine the effectiveness of a light device. In fact, light therapy products with Kelvin temperatures between 2,800 and 3,500° have been found to be effective, just as light therapy products with much higher Kelvin temperatures and CRI's. Current research now shows that specific wavelengths of light and intensity may be solely responsible for treating Winter Blues and related circadian rhythm problems. The SLTBR does not accept Kelvin or CRI measurements nor are they used by any light therapy researcher.

Why Do Some Companies Push Kelvin and CRI?

Some companies still hold to the adage that more is better, and if they can claim a higher CRI or Kelvin temperature, their product must be superior. Interestingly, none of these companies have ever participated in light therapy research or had their findings published. Concentrating on Kelvin and CRI may help them avoid the fact that they are not true light therapy companies. A credible light therapy company supports research and technology, and their products will have been involved in clinical studies to determine their effectiveness.

Why Does Apollo List its Products' Kelvin and CRI Values?

Consumer awareness of Kelvin and CRI has increased to the point that most people ask about Kelvin and CRI. Although these measurements do not convey effectiveness, they do not detract from a product's performance either. In reality, they are byproducts of light therapy technology, and they are listed where appropriate, because so many request the information. Sometimes it is easier to supply additional nonessential information than try to explain why our researchers do not accept Kelvin and CRI as effectiveness standards.

Independent Verification

The non-profit, Lighting Research Center, a group of utility companies, experts and government agencies, established the National Lighting Product Information Program (NLPIP) to provide objective information about the effectiveness of different lighting systems. According to the NLPIP, full-spectrum light does not provide any improved benefits over similar light systems:

"Full-spectrum light sources will not provide better health than most other electric light sources. Recent research has shown that human daily activities are strongly influenced by the solar light/dark cycle. The most notable of these daily, or circadian, cycles is the sleep/wake cycle; but other activities including mental awareness, mood, and perhaps even the effectiveness of the immune system go through regular daily patterns. Light is the most important environmental stimulus for regulating these circadian cycles and synchronizing them to the solar day. Short wavelength (blue) light is particularly effective at regulating the circadian system; long wavelength (red) light is apparently inconsequential to the circadian system. Thus, to maximize efficiency in affecting the circadian system, a light source should not mimic a full spectrum, but instead should maximize only short wavelengths. Even if a full-spectrum light source includes short wavelength light in its spectrum, it will not necessarily ensure proper circadian regulation because, in addition, the proper intensity, timing and duration of the light exposure are all equally important for satisfactory circadian regulation (Rea et. al, 2002)."

The Full-Spectrum Controversy