Like ginseng, schisandra has adaptogenic qualities that help the body deal with stress. A nervous-system stimulant, it's used to treat irritability and insomnia. (Adaptogens are often used in seemingly contradictory ways.) The plant is used to ease coughs, diarrhea, night sweats, and profuse urination. Scientists at Seoul National University have speculated that schisandra could help treat Alzheimer's. The berries contain substances called lignans, which may have liver-protective effects, as well as the antioxidant vitamins C and E. Schisandra has no known significant side effects.