Flipping through your old chemistry notes, you'll recall that negative ions are atoms or molecules with more electrons than protons. They are generally created when water evaporates. Simply by existing as a human on this Earth, you get a nice dose of negative ion therapy every day. Showering with hot water, for example, strips water molecules of their electrons, which go on to join other atoms.
Even before the age of the hot shower, people realized they felt happier in warm environments with moving water—especially seashores and waterfalls. Both environments are more negatively charged than the average environment. Rumors and research circulated until the 1990s when Columbia University put the rumors to a randomized double-blind test.
The study investigated how negative ions affect the winter blues. During a gloomy Manhattan winter, participants with seasonal affective disorder (SAD) sat in a room for 30 minutes daily with ionizers blasting enough negative ions to match the summer air, which is naturally more negatively charged than winter air. After several weeks of treatment, a whopping 58 percent of the experimental group reported over half of their seasonal depressive symptoms left. The participants who did not receive the treatment felt no change.
Thus I want to leave you with a few do's and don'ts when it comes to negative ion therapy: