What type of light is best?

For decades scientists have know that specialized bright light caused a chemical shift in the brain; light suppresses depressive hormones while it produces active ones. Light also regulates circadian rhythms that determine our sleep/wake and energy/mood cycles. But the question has always been which type of light does this? Is all light the same? Is full-spectrum better than broad spectrum? What about ultraviolet light, or is there a single bandwidth that causes these beneficial reactions? Answering these questions has been the primary aim of researchers at the Society for Light and Biological Rhythms (SLTBR), and this quest has taken over two decades to determine.

Non-UV light

In the mid 80's Dr. Raymond Lam and his team at UBC in Vancouver determined that non-UV light was more effective than light with UV emissions. This was a critical discovery in maintaining ocular safety with light therapy. Although Dr. Lam's initial smaller studies showed that UV light was more effective, larger follow-up studies confirmed that UV light was not only unnecessary, but posed significant health risks. Unfortunately, some smaller companies held on to these early flawed studies and promote light therapy with some UV.

Broad spectrum vs. full-spectrum light

In the early 90's Drs. Timo Partonen, Andreas Mangeson and colleagues in Finland reported on several studies comparing broad spectrum, non-UV, and full-spectrum non-UV light. Theirs and subsequent conclusions found equal efficacy between full-spectrum and broad-spectrum white light. However, because patients preferred the color that full-spectrum light produced, most light therapy products incorporated full spectrum technology.

10,000 lux standard

In the following years, Dr. Michael Terman's Group at Columbia Presbyterian Medical College in New York began experimenting with different intensities of light. While most researchers were using light at lower levels for 2 -3 hours, Dr. Terman found that 10,000-lux broad-spectrum light yielded higher responses with only 30 minutes exposure. Since then, most published reports on light therapy recommend 10,000-lux light therapy.

Narrowing in on the effective bandwidth of light

At the same time, Dr. George Brainard's group at Thomas Jefferson University was determined to find if a single bandwidth of light was responsible for shifting circadian rhythms, which caused this hormonal effect. For over a decade, Dr. Brainard has been working to understand how specific bandwidths of light affect the body. Researchers at TJU constructed spheres that could illuminate a monochromatic wavelength of light. Participants placed their heads in these spheres during the middle of the night, when their body clocks were most receptive to light.

Discovery of the decade

What Dr. Brainard and his colleges discovered is perhaps the most significant advancement in light therapy in the last decade. Light in the range of 447-484 nm (nanometers) is responsible for suppressing melatonin and shifting circadian rhythms. Indeed, this specific bandwidth of light is five times more effective than all other wavelengths combined. By using this specific light or boosting it in conventional light therapy, researchers hope to be even more effective in eliciting a stronger and quicker response.

Since Dr. Brainard's ground breaking research, several studies have confirmed the efficacy of this specific bandwidth of light. It is now apparent that specific wavelengths are responsible for suppressing melatonin and shifting circadian rhythms.

Action spectrum of light: BLUEWAVE technology

These studies were particularly encouraging, as they demonstrated response and remission rates that were as high as conventional, full-spectrum light boxes. This specific bandwidth is responsible for shifting rhythms and causing a hormonal response, and is now referred to as the "Action Spectrum" of light. Because of their combined work in determining this action spectrum, Apollo has trademarked this technology as BLUEWAVE technology and has incorporated BLUEWAVE into its existing BRITEWAVE technology.

The BLUEWAVE advantage

Understanding which type of light is responsible for treating Winter Blues and related circadian rhythm problems allows light therapy to be much more effective in helping people respond quicker and enjoy a higher quality of response. Twenty years ago, a Winter Blues sufferer needed 2 - 3 hours of light. Today more people respond better, and they only need about 15 - 20 minutes/day of specialized bright light.