Light Eases Symptoms of Winter Depression : Health: The illness occurs in areas with cold climates and short periods of daylight. Patients who wear a special device report improvement.

Canada: Long, cold, gray, depressing winters in the frozen north. That is often the image of this immense land, and many Canadians might concur. Psychiatrists certainly agree with the depressing part.

Hundreds of thousands of Canada’s 26.5 million people suffer from what is called seasonal affective disorder, or SAD.

It accompanies the onset of winter, causing severe depression, loss of energy, poor concentration, sleepiness and weight gain. Unless SAD is treated, only spring will cure it.

The malady also is found in the northern United States and other countries with cold climates and short daylight periods in winter. The frequency of SAD is greater the farther north one goes.

“We don’t know the specific cause,” said Dr. Anthony Levitt of Toronto’s Clarke Psychiatric Institute, who is doing research with a new visor device that attaches to the head and shines light into a patient’s eyes.

“We know SAD has to do with a geographic, climatic variable that acts on a vulnerability,” he said, “but what triggers it and why one person gets it and the next doesn’t, we don’t know. There may be a genetic component.”

Dr. Raymond Lam of University of British Columbia said one of the strongest theories blames an abnormality in the circadian rhythm, the biological clock that controls sleep and hormones. One synchronizer of the clock is the light-dark cycle.

“We think these people aren’t able to set the clock to the changing day length of winter,” he said.

Light treatment is designed to help reset the clock. Because the light enters through the eyes, Lam wondered if SAD involved a problem in the retina, the part of the eye that receives light.

His studies found “small but significant” differences in the retinas of people who get SAD and those who do not, but said it was too soon to draw conclusions.

Depression in general is a significant health problem because it occurs frequently and is debilitating.

“People with chronic depression have more disability than people with heart disease, lung disease and arthritis,” said Levitt, a psychiatrist born in Australia.

The Clarke Institute’s mood disorders program is coordinating research into light treatment in five North American cities--Boston, Washington, Salt Lake City, Toronto and Vancouver, British Columbia. They were chosen to give the research a geographical spread. About 120 patients are involved.

Scientists are trying to determine the proper dose of light treatment with the visor device, which resembles a miner’s lamp with the light shining backward into the eyes.

Its maker has a special interest. “I’m a SAD sufferer myself,” said Neal Owens, president of SunBox Co. of Rockville, Md.

“I found myself not able to get up on time,” he said. “I was feeling tired even if I got a good night’s sleep. I gained weight. I was unable to concentrate. I just had the feeling of not wanting to be bothered even doing fun things. It was like being weighted down, like being in slow motion.”

Fear of losing his job prompted Owens to seek help at the National Institute for Mental Health. He was identified as a SAD sufferer and given light treatment.

“Within a matter of a few days I was able to get up on time and get to the job,” he said. “I didn’t believe it was the lights, so I stopped using them, and in a week I was back where I was before. I really just couldn’t believe how something simple like lights could help someone.”

Working with the institute, Owens began making light boxes, into which the patient stares.

The trouble with the boxes, Levitt said, is that a person moves his head, which changes the intensity of light that enters the eyes. The Bio-Brite visor, which Owens invented, attaches to the head, keeping the light source a constant 2 inches from the eye.

“It’s very simple,” Levitt said. “That’s what’s so appealing. Only about 15% get some kind of side effects like headaches, eyestrain or irritability. . . . Most people get better in the first week, and it’s reasonably inexpensive.”

He said about 80% of patients respond to treatment, which “is a remarkable rate, but there is no guarantee they will be better next year or that they will stay better.”