Companies in the LED and solid-state lighting (SSL) sectors have promoted numerous research case studies in the past few years that attribute tuned spectral power distribution (SPD) to human benefits in terms of increased productivity, better rest, and even accelerated healing. We have published articles about many of the studies and arguably have been a proponent of what is often called human-centric lighting (HCL). But we and the industry have almost assuredly stepped ahead of the science that would support benefits of lighting, at a certain CCT and SPD, positively impacting our wellbeing.
Don't misunderstand. I firmly believe that researchers will discover a variety of useful ways to apply light that might impact our wellbeing. We know light exposure can impact the human circadian rhythm. But no one right now fully understands the science behind the interaction of lighting and human physiological systems.
We cover some of the facts about light and its impact on humans in our interview with Finelite CEO Terry Clark. That interview and this column were prompted by a multi-author academic paper that discusses the shortcomings in knowledge on the topic and also some of the human physiology that comes into play.
The scientific and medical community seems to have a pretty firm grasp on the human visual system — how we perceive color, how ambient conditions impact our vision, and what types of light might improve our ability to detect objects or see colors optimally. But it seems almost certain that it is non-visual receptors that would be responsible for any link between light and human health.
Still, some of the studies we have published appear at first glance hard to refute. There is likely some amount of legitimate data in those studies, but the topic is way more complex than the published studies have acknowledged. As Terry Clark points out, none of the work accounts for the state of the test subject prior to exposure to light. Proper study would require an adaptation period to bring the collective set of test subjects to a steady state.
I thought deeply about what I'd hope to accomplish in publishing the interview and in writing this column. I think the SSL industry needs to continue and pursue the topic of HCL. There appears to be great potential to favorably impact society and to create opportunity for businesses in the LED-lighting sector. But clearly the industry needs to move a bit more carefully in making claims about the benefits of lighting.
Funding for proper research is going to be an issue for sure. The lighting industry can't likely afford the study required. Fortunately, as Terry Clark has pointed out, brain researchers will have funding to study the impact of light. The LED and SSL sectors need to partner and participate in such research.
Meanwhile, it's fair to ask how this revelation will impact what we publish. As editor, it is my duty to report on news that I think you the readers will find of interest. And if a major company comes to me tomorrow with an HCL study, I will publish an article on it. But we will be quick to remind you of the discrepancy in scientific backing going forward.
Maury Wright, Editor
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