In the JAMA article, Rosenthal described the case study of a 39-year-old novelist who presented in October complaining of increasing fatigue and severe "writer's block." She had gained 2.25 kg and had difficulty avoiding desserts and high-calorie snacks. The results of her physical examination and routine blood tests were all normal. The patient was diagnosed as suffering from SAD, and light treatment was initiated. Using a 10,000-lux light box slanted toward her face for a half hour each morning with instructions to face the box and glance at it periodically without staring, the patient reported in one week that she felt "more energetic and cheerful." She did, however, complain of continued difficulty waking up on time in the morning.
The patient was then instructed to set a bright bedside lamp on a timer to go on two hours before she was due to arise and to begin a regular exercise program, which involved walking outdoors at lunch time.
Studies by Michael Terman, Ph.D., director of the Winter Depression Program at Columbia Presbyterian Medical Center in New York and David H. Avery, M.D., associate professor of psychiatry and behavioral sciences at the University of Washington Harborview Medical Center in Seattle, also have contributed to knowledge about SAD. Avery has shown that simulation of dawn may have an antidepressant effect on the sleeping patient; he hypothesizes that the simulated dawn's light penetrates sleepers' eyelids, acting on the brain to reverse symptoms of depression.
According to Terman, recent studies have shown that the light should be intense to be effective, but that a full spectrum of light is not necessary. Now, the therapy may use ordinary fluorescent light bulbs with an intensity of 10,000 lux, about 10 to 20 times as bright as ordinary indoor light.
A new study from Switzerland showed that light therapy can be used effectively at any time during the day, Rosenthal pointed out. A variety of commercial lighting devices, including a head-mounted light that shines on the face, lights that automatically simulate dawn, and fluorescent light boxes are currently offered. Light therapy devices are also being reimbursed by some insurers, Rosenthal said. He estimates that approximately 10,000 SAD patients are currently being treated with light therapy, which represents approximately one out of 1,000 patients with the problem.
Rosenthal suggested that while the treatment is not dangerous and may seem a benign aspect of normal life, people with severe depression should consult a mental health professional to diagnose their problem and monitor therapy. Rosenthal also said that between 10 percent and 35 percent of depressed patients may have SAD and that physicians should ask about the possible seasonal variation in patients' depression.
Furthermore, a new German study has reported that patients with nonseasonal depression also are helped by light therapy. In the study presented at a recent meeting, Siegfried Kasper, M.D., found that depressed patients who failed to respond to fluoxetine(Drug information on fluoxetine) (Prozac) had an enhanced response to the drug combined with light therapy for five weeks. Light therapy is also being investigated in other psychiatric problems such as eating disorders and obsessive-compulsive disorder, Rosenthal said.
In contrast to patients with severe depression, Americans with the less severe subsyndromal SAD might consider lighting up their day to relieve their sadness, said Rosenthal, who has self-treated himself with light therapy for years.
In the JAMA article, Rosenthal added that while treatment with bright environmental light is generally a first-line therapeutic approach, other treatments including anti-depressants, stress management, exercise and psychotherapy may be useful as well.
"If light therapy is unsuccessful in alleviating a SAD patient's depressive symptoms or is unacceptable for some other reason, it would be reasonable to try a selective serotonin reuptake inhibitor, such as fluoxetine, sertraline(Drug information on sertraline) (Zoloft) or paroxetine(Drug information on paroxetine) (Paxil)," Rosenthal said.
Drawing parallels to the natural seasonal changes in animal behavior and biology, such as hibernation, Rosenthal speculates that depression in winter may be due to the resistance to a natural inclination to hibernate. While most people can override the seasonal decrease in light because of their exposure to artificial light, people with SAD have a higher requirement threshold, he speculated. "We're closer biologically to our animal brethren than we are qualitatively different," he said.