LIGHT AND HEALTH
THE POWER OF
MEASURING Light in the Field By MARIANA G. FIGUEIRO, PHD
Light and Health Research Center at Mount Sinai
The hallmark of the Lighting Research Center (LRC) and the Light and Health Research Center (LHRC) at Mount Sinai has been our commitment to the measurement and characterization of light. Our commitment draws inspiration from H. James Harrington’s observation that “measurement is the first step that leads to control and eventually to improvement. If you can’t measure something, you can’t understand it. If you can’t understand it, you can’t control it. If you can’t control it, you can’t improve it.” In the early 2000s, when the topic of light and health was still in its infancy, the LRC was the first research group to develop a personal light meter that was calibrated to measure circadianeffective light. However, the project’s funder, the U.S. Department of Energy (USDOE), was not willing to fund the development of technology related to health because it was outside their agency’s mandate.
measuring light at the plane of the cornea (rather than the wrist) was important, research subjects showed little willingness to comply with a device attached to their head. Soon thereafter, we were awarded a multi-year, multimillion-dollar research grant from the National Institute on Aging to develop the Dimesimeter, a smaller version of the Daysimeter that would be more appropriate for collecting light data in people living with Alzheimer’s disease and related dementias (ADRD). Measuring roughly the size of a dime (hence the name), the Dimesimeter was a tremendous success, winning a place among the The Scientist magazine’s Top 10 Innovations in Science in 2011.3
The USDOE was, however, very interested in understanding the benefits of daylight, both for energy savings and for providing satisfaction to building occupants. Because daylight is a powerful regulator of the circadian system, we named our device the “Daysimeter” as a playful nod to the similarly named dosimeter developed by the USDOE at its Hanford Site in 1944.1
Our early field studies using the Daysimeter taught us that while
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designing lighting
Figure 1. A lemur (the species Coquerel’s sifaka) wearing a Daysimeter-D in a 2010 study conducted by the LRC and the Department of Evolutionary Anthropology at Duke University.2