There appears to be a connection between air ions and mood. Long touted in the pop literature as a mood enhancer, it was not until the 1990’s that this environmental factor was evaluated for antidepressant properties. The initial clinical trial by Drs. Michael and Jiuan Su Terman at Columbia, reported in the Journal of Alternative and Complementary Medicine, focused on patients with seasonal affective disorder as they experienced major depressive episodes in winter. They found high-density negative ions to be as effective as light therapy in treatment of this disorder.