Light Therapy Changes Brain Chemistry

CONTACT: Chris Chandler at (847) 491-3115
or e-mail at [email protected]

FOR RELEASE: 6 p.m. Wednesday, Jan. 8, 1997

LIGHT THERAPY CHANGES BRAIN CHEMISTRY

EVANSTON. Ill. --- Exposure to bright light could be used as a kind of "drug" to alter the chemical activity in the brain, according to prliminary research findings published in the Thursday, Jan. 9 issue of the scientific journal Nature.

Light therapy is currently used to treat a kind of depression known as seasonal affective disorder (SAD), believed to be caused by the shortness of the day in winter. The theory was that extending the daylight hours would overcome the effects of the season. But, surprisingly, light therapy has proven to be effective even when given during the daylight hours.

Now Fred W. Turek and colleagues at the Center for Circadian Biology and Medicine at Northwestern University have found a possible explanation. In a letter in the Thursday, Jan. 9 issue of Nature, they describe experiments with hamsters in which the effects of serotonin are blocked by exposure to a two-hour pulse of light.

Research has shown that serotonin plays a role in regulating circadian rhythms and also regulating moods. When given to hamsters at a certain time of day, it normally advances the biological clock. But when combined with the exposure to light, the advances are severely attenuated or completely blocked. This suggests that light plays a role in modulating the activity of neurons in the brain that respond to serotonin.

These changes "could have important implications for the use of light as a 'drug' to alter neurochemical activity in the brain," the researchers conlude.

Co-authors of the Nature letter were Phyllis C. Zee, M.D., associate professor of neurology at northwestern University Medical School, and Plamen D. Penev, research associate in the department of neurobiology and physiology at Northwestern University.
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(Dr. Turek can be reached at 847-491-2865 or by e-mail at [email protected] (Dr. Zee can be reached at 312-908-7950 or e-mail at [email protected]