Researchers from Johns Hopkins university found caffeine can sharpen memories for up to 24 hours after it's consumed. They tested more than a hundred participants who normally did not drink coffee, tea, or Cola.

The subjects were asked to look at every day images on a computer screen and, five minutes later, half were given 200 milligrams of caffeine, about the amount in a strong cup of coffee. The other half received a placebo. When they came back the next day, they were asked to label the pictures as old, new, or similar to the original images.