Getting 45 to 60 minutes of light therapy midday, each day, is easing depression in some women who suffer from bipolar disorder, say University of Pittsburg researchers in the journal Bipolar Disorders.

“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,” says Dorothy Sit, MD, University of Pittsburg assistant professor of psychiatry, who noted that there are limited treatments for the depressive phase of bipolar disorder. People with bipolar disorder are sensitive to changes in ambient and seasonal light, and researchers are hoping to reduce their risk of suicide through consistent light exposure.

Women in the study who used a light box for 45 to 60 minutes a day, specifically during the midday, saw the greatest declines in the common symptoms associated with depression and mania that tend to occur all at once, including racing thoughts, irritability, sleeplessness, anxiety and low moods.

Sit cautioned that if the light box is used too early in the day, such as early morning, it can disrupt circadian rhythms and sleep patterns and minimize the effectiveness of light on mood overall.