More threads by David Baxter PhD

David Baxter PhD

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Winter Mood
January 17, 2006
by Emily Hager,

The cold dark days of winter are known to lower the spirits of many people. Now scientists have new recommendations for a therapy that can make you feel like spring is in the air. This ScienCentral News video has more.

Morning Shower
Every morning, sometime between packing four school lunches, sorting through hats and mittens, and making sure her kids' homework is in order, Luanne Hughes takes a light shower. For thirty minutes 38-year-old Hughes basks in the rays of a 10,000 candlepower light.

Hughes is among an estimated four to six percent of Americans that develop seasonal affective disorder, a type of depression that sets in as the winter days grow short. People who develop seasonal affective disorder, also aptly known as SAD, begin to have trouble getting out of bed in the morning, they lose interest in social activities, tend to withdraw, and generally feel lackluster and blue. Other statistics suggests that up to 20 percent of Americans develop minor symptoms of SAD each winter. Hughes says her daily light shower is a way she can literally brighten her mood without relying on medications. "I just don't like being on drugs," she says.

Light therapy is well established as a treatment for SAD. But doctors now have new recommendations for when SAD patients should receive light therapy. Columbia University psychologist and a leading SAD expert Michael Terman, and his colleague and wife Jiuan Su Terman, reported in the journal CNS Spectrums that SAD patients should time their daily dose of light therapy — ideally thirty minutes in front of a 10,000-lux light — according to their own biological clocks.

"We're not talking about an optimum time in terms of the clock on the wall," says Michael Terman, "we're talking about an optimum time in terms of the clock in the brain."

Terman says the best time for light therapy is about eight and a half hours after our brains begin to secrete the hormone melatonin. Melatonin is a good measure of our natural sleep cycle. It is normally released a few hours before we go to bed, and is what makes us gradually grow sleepy in the evening. The hormone then tapers off between seven and a half, and nine and a half hours later. Terman says the end of the melatonin cycle, is the "hot spot," or best time for light therapy. But, he points out, but that "hot spot" is different for everyone.

"If you're a lark, that means you're going to need light therapy earlier in the morning than if you're an owl, but the light therapy will be effective in both cases," says Terman.

Ten thousand-lux artificial lights, which give off the equivalent amount of light of a bright summer day, help relieve the symptoms of SAD because they reset a person's daily biological clock. In the winter, when there is less light in the morning, our bodies' biological clocks can drift away from the actual local time. This is called a "circadian misalignment," says Helen Burgess, assistant director of the Biological Rhythms Research Laboratory at Rush University Medical Center. Most of us "Feel [the misalignment] when we wake up," says Burgess, "But most of the time we can sort of continue on."

But for people with a predisposition for SAD, either due to genetics or because they live along northern latitudes, a circadian misalignment can lead to depression. Studies by the Termans and others show that when light therapy is given at the end of the melatonin cycle there is an antidepressant effect because our biological clocks are reset to the local time.

University of Vermont clinical psychologist Kelly Rohan says light therapy is certainly a good way to treat SAD, but she points out that it is not convenient for everyone and that long-term compliance with the therapy is low.

"It's hard to get people to take an antidepressant," Rohan says. "Sitting in front of a light box for 30 minutes is just not practical."

Rohan recommends that SAD patients also receive cognitive behavioral therapy so even if they fail to get their daily dose of light, they have additional mental skills they can use to keep their spirits up. She says 90 percent of her patients "prefer and expect" both types of therapy.

Terman says people using light therapy should never look directly into the light. To make the therapy most convenient and to time it to an individual's biological clock, he recommends integrating light boxes into a person's normal morning routine. He says people could get their light therapy as they eat breakfast and read the morning newspaper for example, or as they sit at their desk and work.

To squeeze the treatment into her hectic life, Hughes recently mounted her light box on the wall over her treadmill. Now she can get her morning workout and shower all in one.
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