People with bipolar disorder are known to be sensitive to changes in outdoor ambient light and to seasonal changes and a small-scale U.S. study has shown encouraging results for light therapy. The light therapy was used to treat the depressive part of the disorder and the women who participated in the study were given light boxes and instructions on how to use them at home. Those who received morning light developed a mixed state with symptoms of depression and mania - racing thoughts, irritability, sleeplessness, anxiety and low mood - occuring all at once but those who used their light boxes at mid-day had a much more stable response and of the nine women treated six showed some sign of improvement. Optimal response was observed with mid-day light therapy for 45-60 minutes daily.
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