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Researcher Unravels the Mysteries of Light and the Human Body


Joan Roberts, Ph.D., professor of chemistry and chair of the Department of Natural Sciences.
Photo courtesy of Joan Roberts

“Take two aspirin and call me in the morning.” For most of us that old saw is simply a jab at overworked doctors, seeking a few pager-free hours in their off time. But to Joan Roberts, Ph.D., professor of chemistry and chair of the Department of Natural Sciences, it might have a more literal meaning.

Roberts is one of a growing cadre of scholars doing research in the arcane-sounding field of chronotherapy in which doctors seek to administer medications at the time of day at which they will be most effective.

Chronotherapy isn’t a new field. “The Chinese thought of it 4,000 years ago,” Roberts said. “We’re just trying to define it using Western scientific techniques.”

Much of the interest in the field stems from discoveries involving how the daily visible light/dark cycle controls the body’s internal rhythms. Keeping this balance of dark and light is essential for maintaining human health.

Prior to our understanding of the power of the dark/light cycle, Roberts said, people assumed that the only use the brain had for visible light was in processing visual images. But it turns out that light—particularly blue light—also affects a region of the brain called the hypothalamus, which sets the body’s circadian rhythm: our daily cycle of wakefulness and sleepiness, reproductive hormones, stress adaptation and metabolism.

Roberts, an organic chemist by training, got interested in the field while doing postdoctoral research in pharmacology. “I started to look at how light might affect drug behavior,” she said. “Friends were studying the photochemistry of the skin, so just to be different, I decided to study the photochemistry of the eye.”

When Roberts first came to Fordham in 1977 her interest was in defining the hazards of ultraviolet light and bright blue light, which are linked to cataracts and macular degeneration. But after a 1990 sabbatical in England, where there is little sunlight in the winter, Roberts became interested in seasonal affective disorder (SAD) in which some people become severely depressed during dark, northern winters.

The depression is related to a depletion of dopamine and serotonin and can be treated by the use of light boxes, timed to simulate extra morning daylight. But Roberts wondered whether the malaise that comes with SAD might cause people with winter blues to also have depressed immune systems that could be activated with light therapy. To find out, she treated both SAD patients and a control group with light therapy—and discovered that everyone’s immune system perked up in the presence of light.

Simultaneously, researcher Francois Levy was discovering that some aspects of the human immune system work better at night, while others work better in daytime. And G.J. Maestroni and Paolo Lissoni discovered that cancer chemotherapy drugs were three times more effective if administered in the evening, apparently because of a synergism between chemotherapy and melatonin.

At the same time, there are disturbing studies conducted by George Brainard and David Blask that indicate that women who work late shifts under artificial light have a higher risk of breast cancer. It’s not the light itself that causes the problem, Roberts said, but “having light at the inappropriate time of day.”

“The production of estrogen, which plays a role in the development of some breast tumors, is increased by inappropriately timed light,” she said. And it’s not just women who face this risk: ill-timed light can also increase men’s production of testosterone, which is related to the risk of prostate cancer.

The color of the light is also important. Blue is a wake-up call, signaling the clear skies of morning. Redder light signals the warmer glow of late afternoon. For this reason, Roberts isn’t a fan of using only fluorescent lights, even though they are more energy efficient than the orange-red glow of old-style incandescent bulbs. Following Mother Nature by using daylight or fluorescent lighting in the morning and incandescent bulbs only in the late afternoon, she said, is both energy efficient and healthy.

Currently, Roberts has two basic goals. One is to continue her research, extending knowledge of chronotherapy as it relates to cancer and other diseases. The other is to inform policymakers, lighting designers, architects and the medical community about the importance of considering not just the efficiency of a particular lamp source but the effect of spectrum and timing of ambient light sources on human health.

As chair of the Department of Natural Sciences, Roberts is constantly speaking with scholars in fields other than chemistry: physicists biologists, mathematicians, and computer scientists. She loves the interdisciplinary nature of her position at the Lincoln Center campus.

And she’s found that one of the best ways to broaden her horizons is by teaching core chemistry and biology courses to non-science undergraduates because it forces her to stay current in the latest developments in those fields.

“I get some of my best ideas teaching science to liberal arts students,” she said.

By Richard A. Lovett


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