Light a sage-scented candle or set out a few bowls of sage potpourri and you could chase away brain fog and improve alertness, focus and memory by 21 percent in just 10 minutes, say researchers at the Smell and Taste Treatment and Research Foundation in Chicago.

That's because the rich herbal aroma of sage stimulates the brain's focus-enhancing frontal lobe, plus it energizes the limbic system--the brain region responsible for memory formation.