Researchers from the University of Pittsburgh School of Medicine's Western Psychiatric Institute and Clinic have found that bright light therapy can relieve some patients of bipolar depression.
The team of researchers, led by Dorothy Sit, M.D., assistant professor of psychiatry, studied nine women with bipolar disorder to examine the effects of light therapy in the morning or at midday on mood symptoms.
"There are limited effective treatments for the depressive phase of bipolar disorder. While there are treatments that are effective for mania, the major problem is the depression, which can linger so long that it never really goes away," said Dr. Sit.
For the study, the researchers gave light boxes to women with bipolar depression and also gave instructions on how to use them at home. The women used these light boxes for two-week stretches of 15, 30 and 45 minutes.
Some patients gave a good response to the light therapy with disappearance of depression symptoms, and continued with the therapy for additional three or four months.
While four patients received morning light, five used their light boxes at midday. The participants also continued with their prescribed medications till the end of the study period.
"Three of the women who received morning light initially developed what we call a mixed state, with symptoms of depression and mania that occur all at once - racing thoughts, irritability, sleeplessness, anxiety and low mood. But when another group began with midday light therapy, we found a much more stable response," said Dr. Sit.
Six of the nine women, who got the therapy, did respond to a level and many even got full recovery from depressive symptoms.
However, the majority of the patients achieved best recovery with midday light, some even responded more fully to a final adjustment to morning light.
"People with bipolar disorder are exquisitely sensitive to morning light, so this profound effect of morning treatment leading to mixed states is very informative and forces us to ask more questions. Did we introduce light too early and disrupt circadian rhythms and sleep patterns?" said Dr. Sit.
"In our study, 44 percent of patients were full responders, and 22 percent were partial responders. Light therapy, therefore, is an attractive and possibly effective augmentation strategy to improve the likelihood of full-treatment response," he added.
The researchers noted that with midday light therapy for 45 or 60 minutes daily an optimal response in patients could be achieved.
The study was published in the journal Bipolar Disorders.