Light therapy can help relieve seasonal affective disorder

Claire Gliddon is usually a cheery sort — downright perky, even. Get her talking about her charity work with Project Linus, which provides blankets to needy children, and she gets as excitable as a child herself.

Yet the 52-year-old Fair Oaks, Calif., resident also has these moods, these bouts of sluggishness and ennui, that must be acknowledged and overcome.

When they come — and all she has to do is glance at the calendar to guess at their arrival — Gliddon seeks illumination.

Literally. She'll flip the switch on her full-spectrum lamp, which can produce 10,000 lux (a measurement of apparent intensity) of light, and sit near it for 20 minutes to help chase away her blues.

As many as 33 million Americans have reported depression with the onset of winter, according to the American Academy of Family Physicians. Gliddon is one of an estimated 14 million Americans diagnosed with seasonal affective disorder, which goes by the acronym SAD.

From late fall to late spring, when daylight is at its scarcest, SAD can affect people's energy, mood, creativity, productivity and, in more severe cases, bring on major depression.

Lack of light, researchers say, can fool the body into making too much melatonin, which regulates the sleep-wake cycle. A person's circadian rhythm simply gets out of whack.

Prolonged darkness also depletes levels of serotonin, a neurotransmitter that regulates moods.

Scientists are almost unanimous in labeling SAD as a specific form of depression, though a journal study published recently by Norwegian researchers cast a skeptical light.

The study looked at the population in northern Norway over two winters and determined that there was no "spontaneous complaint" of depression during the dark months. Lead researcher Vidje Hansen concluded, "SAD is not a valid medical construct" and recommends that the condition be called "recurrent depression with seasonal patterns."

Dr. Robert Ruxin, chief of psychiatry for Kaiser Permanente in Sacramento and Elk Grove, Calif., has no doubts about SAD.

"We see people who really don't have any mood issues the majority of the year and tend to have issues every winter," Ruxin said. "And then there's people with chronic depression who tend to have more trouble in winter than the rest of the year."

Among the treatments for SAD are cognitive behavioral therapy, medications to regulate serotonin and melatonin levels, and light therapy.

Gliddon is one who has seen the light. And her full-spectrum light box has made all the difference, she said.

"If you don't want to do something chemical, this is a really big help," Gliddon said. "Prozac alone wouldn't do it for me. I need the light therapy."

An early adopter of light therapy, Gliddon purchased her lamp nearly 20 years ago from a Canadian company. She paid nearly $1,000 for it. In recent years, as studies have confirmed the effectiveness of light therapy, the lights are more widely available and retail for $150 to $200.

"It's very bright," she said. "I crochet the whole time, or read the newspaper. I don't think I could just sit there doing nothing."

Gliddon is so often quick with a joke and a kind word that it's difficult to imagine her as grumpy and lacking motivation.

But she's had her moments, she said.

"You just start slowing down and want to sleep and eat more," she said. "You react like it's nighttime when it's really only 5:30."

Now, she'll open the shutters in her house, turn on all the lights and, each midmorning, bask in the glow of her full-spectrum light.

"I never skip a day," she said.