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| Wearing the Daysimeter |
The Lighting Research Center is forming a collaborative group of researchers from around the world to collect data in different lighting applications using a special light measuring device known as the Daysimeter.
“The group’s goal is to create a cooperative forum of manufacturers, scholars, scientists, and physicians who are already working in clinical applications and work environments where photobiology and circadian light exposure could be important for health and productivity,” said Mark Rea, PhD, the director of the LRC.
Research has shown that the human circadian system responds to light in a dramatically different manner than the visual system. Light is the main stimulus that helps the human body clock, and thus circadian rhythms, to keep a synchronized rhythm with the solar day. Studies have shown light to have an impact on people’s health and well-being. However, until now, it has been nearly impossible to measure a person’s quantity and quality of circadian light exposure accurately.
Measuring circadian light exposure
The Daysimeter, a field research tool developed by the LRC, is the world’s first device to characterize light accurately by measuring spectrally weighted intensity, as well as timing and duration, of circadian light entering the eye, which affects the human body’s clock. The device also measures conventional light levels and records head movements in order to differentiate between rest/sleep periods and active/awake periods.
Ultimately, the Daysimeter will enable the design of light sources, luminaires, and lighting techniques that help people to maintain regular circadian functions such as the sleep/wake cycle and hormone production, which in turn may improve their health. Rea emphasized that the LRC will be exploring a number of clinical and special applications where people could benefit from lighting tuned to the circadian system. These include hospitals, intensive care units, and assisted-care facilities where patients do not have regular exposure to daylight or darkness, as well as work environments that do not allow for customary light and dark exposures such as military operations aboard submarines and in bunkers.
Accelerating the understanding of circadian light exposure
“The work of the Daysimeter User Group,” explained Rea, “may lead to a better understanding of many health-related issues.” Those issues, he said, include:
- How premature infants develop
- Appropriate learning environments for school children
- Improved sleep for people with Alzheimer’s disease and their at-home caregivers
- Teenagers with delayed sleep phase disorder
- Biophysical and epidemiological concerns for senior-care residents, night-shift workers, travelers with jet lag, and others with altered light-dark exposures and sleep patterns
As part of the Daysimeter User Group, Rea says the LRC will participate in establishing a common protocol for the use of the Daysimeter. “Because this is a research tool that is still in development, a common protocol is needed so that we can make an apples-to-apples comparison of data from different groups,” said Rea.
LRC scientists will also conduct research, demonstration, evaluation, and educational activities related to the use of the Daysimeter.
The first meeting of the Daysimeter User Group is scheduled for March 7, 2007, at the LRC in Troy, N.Y. Anyone interested in participating may contact Patricia Rizzo at 518-687-7100 or rizzop2@rpi.edu.
For more information. . .
See the LRC project sheet, Daysimeter User Group.
Read about the development of the Daysimeter in the October 2005 newsletter.
Read “The Daysimeter: A device for measuring optical radiation as a stimulus for the human circadian system” by Andrew Bierman, Terence Klein, and Mark Rea, published in the journal Measurement Science and Technology.
View a list of LRC-authored papers on light and health, including circadian phototransduction, on the Light and Health Web site (www.lrc.rpi.edu/programs/lightHealth/).
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Lighting Research Center, 21 Union Street, Troy, NY 12180 USA 
