Light Therapy

A Safe, Simple Way to Lift Your Moods

The scenario is familiar: Cooped up in windowless meeting rooms all day, you suddenly have the urge to make a break for it and take advantage of the brilliant sunshine outside. Ah, that feels better. Fifteen minutes later, you return to work renewed and refreshed.

You've just treated yourself to a mood-elevating dose of light therapy. Though its roots are 2,000 or so years old--great Greek geniuses like Herodotus and Hippocrates recognized its healing power--light therapy is still considered a scientific frontier, says George Brainard, Ph.D., professor of neurology and director of the light research program at Jefferson Medical College in Philadelphia.

"The very best data we have for light therapy is for its ability to help relieve seasonal affective disorder (SAD)--a form of depression that many women experience during the fall and winter, when there are fewer hours of daylight," says Dr. Brainard. "Those studies date back to just 1982. And only a handful of medical schools in this country have full-fledged light research programs, including ours here at Jefferson," he notes.

A CURE FOR THE RAINY-DAY BLUES

Unfortunately, doctors who use light for therapy can't depend on the weather. When it's dreary or nasty outside, it's harder to take advantage of nature's free light treatment. But there is an artificial alternative. A light box that mimics the sun's natural rays has been shown to be effective against SAD.

Natural or artificial, light therapy need not be intense or prolonged to lift your mood. A study done in Switzerland showed, for example, that a daily 30-minute walk in the morning--even on a cloudy morning--is as effective for treating seasonal affective disorder as using a special light box, says Dr. Brainard.

"The brightest light box that we recommend for therapeutic use measures 10,000 lux at eye level," he says. "That's equivalent to daylight about a half-hour after sunrise." (Roughly translated, 10 lux equals the lighting power of a single candle at a one-foot distance from the eye.)

"So an early-morning walk may be exactly as effective as sitting in front of your light box," says Dr. Brainard. For the sake of comparison, he notes, the light at midday on a clear, sunny day measures 100,000 lux.

Experts know that light therapy works, but they don't exactly know why or how. They do know that light affects the secretion of melatonin, a hormone produced in the pineal gland. The pineal gland is controlled by the hypothalamus, the part of the brain that serves as the body's "clock."

Melatonin secretion occurs mainly at night, and light suppresses the release of the hormone, explains Norman E. Rosenthal, M.D., chief of the Unit of Outpatients Studies and staff psychiatrist at the National Institutes of Mental Health in Bethesda, Maryland. It's unclear whether SAD is related to melatonin. Nevertheless, Dr. Rosenthal and his colleagues have effectively treated SAD by exposing patients to bright light for several hours a day.

SHEDDING NEW LIGHT ON WOMEN'S HEALTH

According to Dr. Brainard, what researchers are learning about the therapeutic use of light has a great deal of promise--especially for women.

As a proven treatment for SAD, light therapy is good news for the millions of women who become clinically depressed during winter's shorter, darker days. "Perhaps as many as four times more women than men seek treatment for SAD symptoms," says Michael Terman, Ph.D., director of the winter depression program and the light therapy unit at Columbia-Presbyterian Medical Center in New York City.

But women may benefit in other ways. "A handful of small studies indicates that light therapy may be effective for easing the symptoms of premenstrual syndrome," says Dr. Brainard. And, he says, there's additional hope for women who are unable to conceive due to overly long menstrual cycles.

"As far back as the 1960s, researchers found that light therapy could normalize long menstrual cycles," says Dr. Brainard. "In recent years, a research team working with Daniel Kripke, M.D., at the University of California at San Diego repeated those studies with good results," says Dr. Brainard. In Dr. Kripke's studies, it was shown that exposure to light during the night for three days during the middle of the menstrual cycle significantly shortened and normalized long, irregular menstrual cycles.

And light therapy has been found to be helpful for women whose sleep is disturbed by jet lag and shift work. One group of researchers at the Biological Rhythms Research Laboratory at Chicago's Rush-Presbyterian­St. Luke's Medical Center concluded that controlling light and dark artificially can overcome the sleep problems encountered by shift workers.

LIGHT THERAPY DO'S AND DON'TS

Using a light box is pretty simple, according to Brenda Byrne, Ph.D., director of the Seasonal Affective Disorder Clinic affiliated with the light research program at Jefferson Medical College. All you have to do is plug it in, sit in front of it and follow the manufacturers instructions for proper light exposure.

For light therapy to work, explains Dr. Brainard, the light must illuminate your retina, the part of the eye that conveys light signals to the pineal gland. "But it's very important to get a specially designed light box from a reputable dealer," says Dr. Brainard.

Whatever you do, warns Dr. Brainard, don't confuse light boxes with tanning lights--you can't get safe light therapy at a tanning salon, even if you wear protective goggles. "Ultraviolet rays from tanning lamps can seriously damage your eyes," says Dr. Brainard. "For that same reason, never stare directly at the sun, either."

Dr. Byrne offers these other do's and don'ts for light therapy.

Get the go-ahead from your doctor. Depression can be a serious disorder. Don't buy a light box to treat your blues before talking to your doctor about your symptoms.

Let there be light before breakfast. Begin your day with a 35-minute walk or light-box session, says Dr. Byrne. Morning light treatment is especially helpful for people with seasonal affective disorder who find it hard to get up in the morning. If you can't arrange a morning session, pick a time that's not too late in the evening and stick to it, suggests Dr. Byrne.

Read the directions. The proper distance between you and the light will vary. Follow the manufacturer's directions.

Don't count on the light of a sunny window, says Dr. Byrne. "Daylight reflects off even clear glass, so it's hard to know just how much light you're getting through a sunny window."

Don't just sit there--do something! Use your 30-minute daily light-box session to your advantage, suggests Dr. Byrne. "Many women use their light-box time to meditate, eat breakfast, ride an exercise bike, read or put on makeup. Just make sure that you're sitting close to the box."