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Prescription Lighting Is Closer to Reality Than You May Think

Enough has been learned in the past few years “to make a difference in people’s lives.”

Although the international lighting community does not yet know enough to prescribe a certain type of electric lighting to meet the specific needs of specific individuals, enough has been learned in the past few years “to make a difference in people’s lives,” according to Mariana G. Figueiro, Ph.D., director of the Lighting Research Center, a professor of architecture at Rensselaer Polytechnic Institute, and a member of the “Prescription Lighting” discussion panel convened at the National Lighting Bureau’s 7th Annual Lighting Forum. Robert Soler, vice president of human biological technologies and research with BIOS Lighting, was the other panelist. EdisonReport Editor and Publisher and Illuminating Engineering Society (IES) Past President Randy Reid moderated the discussion.

The focus of the panel was prescription lighting, but both panelists agreed that no widely accepted definition of the term exists. In fact, as Dr. Figueiro emphasized, no widely accepted definition of “circadian lighting” exists either; different people mean it to signify different things, especially spectral distribution of light. Spectral distribution, however, is only one aspect of light that needs understanding if light is to be prescribed. Other aspects include intensity of the light, the amount of light, how the light is distributed, and when the exposure occurs. “Optic history” is also a factor, Soler says, noting that someone who routinely works outdoors all day is affected far less by “blue light” — light that, undetectable to the human eye, emphasizes the blue portion of the spectrum — than an individual who spends all or most of the day indoors, such as hospital and nursing-home patients, Alzheimer’s victims, and prisoners, among others.

Although far more must be learned to have what could be termed “full-blown” prescription lighting, Dr. Figueiro and her Lighting Research Center team are already envisioning a wearable instrument dubbed a personal lighting device (PLD). The device would know a person’s lighting prescription and, as the person moved about an office or similar area, it would adjust the overhead, ambient lighting to maintain the individual’s prescribed exposure.

“We are far from that situation right now, because more research is needed,” says Figueiro. “Nonetheless, we do know that lighting affects people’s health. In the case of Alzheimer’s patients, for example, a population that stays indoors all day, circadian-effective lighting has been shown to improve patients’ sleep, lessen their agitation, and reduce their depression.

Although no one yet knows how to prescribe lighting for specific individuals, prescription lighting is now installed in virtually every illuminated space. According to National Lighting Bureau Executive Director John Bachner, “We now know that lighting affects people in ways that, until 20 or so years ago, we were totally ignorant of. As such, for better or for worse, whoever designs a lighting system is actually designing a system that affects human health and performance. For the most part, however, we don’t know how. But it surely explains why it’s so important to have an experienced lighting designer on your side.” The Bureau offers a free lighting-designer directory that includes some 5,500 listings and guidance on how to make an effective selection.

For those who want the best-possible light to maintain their health and optimize their performance, both panelists agreed on one approach: Get up and go outside in the morning and darken the bedroom (or wear a sleep mask) at night.

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