Study Confirms Light Therapys Role in Treating Winter Depression
Lead Researcher: Michael Terman
Although artificial bright light was first described more than 15 years ago as an effective treatment for seasonal affective disorder (SAD), or winter depression, many health professionals and insurance companies continue to view it suspiciously as an unproven treatment lacking rigorous scientific support. The results of a six-year controlled study with more than 120 subjects, published in the Oct. 14, 1998, issue of the Archives of General Psychiatry, should help put those doubts to rest.
The National Institute of Mental Health-funded study, led by Dr. Michael Terman, professor of clinical psychology and director of the Winter Depression Program at the New York State Psychiatric Institute, definitively demonstrates that bright light is an effective treatment for SAD and that it is most effective when administered in the morning. Dr. Termans study was accompanied in the journal by two other controlled studies with similar findings.
This is a watershed event in our field, said Dr. Terman of the simultaneous publication of the three controlled studies. It is clearing up controversies that have plagued us for years. Dr. Terman believes that the three studies may persuade both the federal government and major medical societies to give their stamps of approval to light therapy for SAD, clearing the way for wider use. Dr. Termans study may bring attention to another controversial treatment: Surprising and preliminary findings suggest that negatively ionized air could help people suffering from SAD.
Seasonal affective disorder occurs primarily during the short days of late fall, winter, and early spring. In addition to feeling depressed, sufferers often find themselves sleeping more than normal, craving food (especially carbohydrates), and gaining weight.
In a pioneering study in 1984, NIH researchers described SAD and its successful treatment by bright light. However, studies of SAD since then have faced two problems. Many of them have included too few patients to convincingly attribute positive results to bright light rather than to chance. Also, since patients know whether they are receiving light treatment, it has been difficult to design studies with a credible control group receiving some form of placebo.
Over the course of six years Dr. Terman and his colleagues were able to recruit 158 subjects, 124 of whom completed the study and met all requirements for SAD. For a placebo, Dr. Terman used a negative air ionizer, which emits a stream of negatively charged electrons. Some previous research hinted that sustained exposure to negatively ionized air might have mood-elevating effects, but Dr. Terman believed that a relatively brief 30-minute exposure would not have any effect. The treatment worked as a placebo because patients thought they were receiving a form of treatment but could not physically sense the presence of negative ions.
In different samples of the trial between 26 percent and 37 percent of patients receiving bright light in the evening showed essentially complete remission of winter symptoms but became depressed again once treatment stopped. Among those receiving bright light in the morning, 47 percent to 65 percent responded. While morning light worked better for most patients, a small number of patients responded better to evening light.
Patients receiving low densities of negatively ionized air showed no significant improvement and served as an effective control group. But people receiving high densities of negatively ionized air showed an unexpected benefit. By the end of the study period, 40 percent became virtually symptom-free.
For us it was a complete surprise, said Dr. Terman. Although he defends the study as being controlled, having statistically significant and robust results, he cautions against placing too much faith in a single study. Without independent replication you have to be very cautious about your claims. Encouraged by these findings, he has received a five-year grant to further study the effects of negative air ionization and light therapy.