The Daysimeter

Nightshift workers have known for years that working nights and sleeping days can wreak havoc on the body’s internal clock. But scientists are just now catching up with some useful technology that might help reset that clock. Here’s an excerpt from an article Cheryl wrote for Scientific American, published online last week:

In an effort to gauge exactly how light affects our body clocks, Rensselaer Polytechnic Institute's Lighting Research Center (LRC) in Troy, N.Y., has developed a device called a Daysimeter. Small and ear-mounted—like a wireless cell phone headset—it has three sensors that measure head movement, bright light (or lux, a measurement of the light used for daytime vision), and blue visible light (also known as circadian light). Circadian light—radiated by the sun as well as computer and television screens—helps balance certain hormones and neurotransmitters in the body, but only in specific doses and at certain times of day. Too much of this light can throw off the body's internal clock, which researchers believe leads to problems such as fatigue and poor health…

"We envision the Daysimeter, along with other biological markers [such as hormones] will allow us to get a more detailed circadian profile of a particular person," says LRC director Mark Rea, a Rensselaer professor of cognitive science. Researchers can measure the effect of circadian light exposure on hormone levels through blood samples collected from subjects. "We're fully expecting that we'll see variation among the population," he notes.

Rea envisions "real-time light prescriptions" to help people receive or avoid light at the appropriate times. Simple measures to control when and how much circadian light we receive could help nightshift workers stay alert on the job and sleep more effectively during the day, help cure jet lag, decrease depression, and generally help everyone get a proper night's sleep.

The ability to modify circadian rhythm could potentially mitigate the negative health effects that some researchers believe are brought on by disruptions to the light-dark cycle. Recent studies have found a link between health and changes in the natural circadian rhythm. The Journal of the National Cancer Institute published a series of articles, for example, that showed night shift workers had a higher incidence of breast cancer; and, last year, the World Health Organization's International Agency for Research on Cancer cited night work as a potential breast cancer risk factor…

Rea admits the LRC is a long way off from making their instrument available to the public. But researchers in the science of circadian rhythm are excited by the prospect of devices that may one day help people understand their own particular light-dark cycle and how to keep it in balance.

For the full article, click here: www.sciam.com