Hydrotherapy may boost energy, ward off insomnia and possibly boost immunity, according to a study.

In Germany, a study showed people who had COPD, a lung disease, had fewer infections and a greater number of cells that fight infection after applying cold water to their upper bodies for ten weeks.

Looking for a little energy? Try soaking your feet in hot water followed by cold water.

Some practitioners believe that, at least with cold water therapy, it works temporarily by diverting blood flow away from extremities and pushes it toward internal organs.