Forum for Illumination Research, Engineering, and Science (FIRES)

Standards Category: Light and Health
Figure 1.

Circadian Lighting: a Neuroscientist’s Perspective

By Douglas Steel, Ph.D., NeuroSense

The purpose of this article is to evaluate from a biological standpoint the rationale for the establishment of a Circadian Lighting standard put forward by UL under the direction of Dr. Mark Rea of the Lighting Research Center at Rensselaer Polytechnic Institute. This critique is limited in scope but also applies to utilization of the Circadian Stimulus (CS) calculator also developed by the LRC. Read More

Figure 1.

Circadian Lighting: An Engineer’s Perspective

By Ian Ashdown

Whether you call it “circadian lighting,” “biologically effective lighting,” or some other name, the principle is the same: the color and intensity of light can be used to regulate the timing of our biological clocks, or “circadian rhythms.” For architects and lighting designers, this is an opportunity to provide healthy and comfortable environments for building occupants. Read More

Figure 1: An example of the stroboscopic effect, measured with a short duty cycle and 100% modulation

Concerns in the Age of the LED: Temporal Light Artifacts

By Dr. James M. Gaines

Flicker and stroboscopic effect are presently hot topics in lighting, along with other subjects like blue light (subject of a recent FIRES article). A National Electrical Manufacturers Association (NEMA) standard, NEMA 77, addresses measures for temporal light artifacts (TLA), which is an umbrella term covering both flicker and stroboscopic effect (as well as phantom arrays. The NEMA metrics for flicker (short-term flicker indicator, Pst) and stroboscopic effect (Stroboscopic Visibility Measure, SVM) are both based on experiments done with many human observers, to measure average human sensitivity to flicker and stroboscopic effects. Read More

A Reality Check on Blue Light Exposure

By Eric Bretschneider, Ph.D

How often do we hear about the dangers of blue light from LEDs? Such discussions inevitably include statements about “the intense blue peak” in LED lighting and the potential for damage from the massive amounts of blue light present in LED lighting.

The whole argument sounds plausible enough when we look at the spectrum of a typical white LED. The spectrum below is for a typical white LED with a CCT of 4,000 K at levels that approximate a typical commercial or retail environment (400 lux). The isolated peak in the blue clearly stands out, but does it really represent a massive dose of blue light? Read More

Melanopic Green The Other Side of Blue

By Ian Ashdown, P. Eng. (Ret.), FIES
Senior Scientist, SunTracker Technologies Ltd.

Numerous medical studies have shown that exposure to blue light at night suppresses the production of melatonin by the pineal gland in our brains and so disrupts our circadian rhythms. As a result, we may have difficulty sleeping. It is therefore only common sense that we should specify warm white (3000 K) light sources wherever possible, especially for street lighting.

True or false? Read More

The Science of Light and Health: How to Interpret the Claims That Underlie Medical and Wellness Effects

By Douglas Steel, PhD
Founder and Chief Scientific Officer of NeuroSense

These are transformational times for the lighting industry. The cost of LED-based products has dropped dramatically. At the same time, increased sophistication and capabilities of tunable LED arrays, controls, and sensors now enable the commissioning of platforms that can precisely control light intensity, correlated color temperature, and relative spectral content. Read More

Figure 3 – Infrared “smudge” (see text for explanation).

The Science of Near-Infrared Lighting: Fact or Fiction

By Ian Ashdown, P. Eng. (Ret.), FIES, Senior Scientist, SunTracker Technologies Ltd.

There is a common-sense argument being presented in the popular media that since humans evolved under sunlight, our bodies must surely make use of all the solar energy available to us. Given that more than 50 percent of this energy is due to near-infrared radiation, we are clearly risking our health and well-being by using LED lighting that emits no near-infrared radiation whatsoever. Read More