A night on a bed of roses could sharpen your memory. The purpose of sleep remains a mystery, but one idea is that slumber replays new experiences to facilitate their inclusion in long-term memory storage. To explore this notion, volunteers in a rose-scented room played a computer version of the card game Memory, where they had to remember locations of paired cards that flashed on the screen for a few seconds at a time. Later, while they slept, researchers exposed them to the rose fragrance, because odors are well known for bringing back memories. Volunteers performed better at the game when given the scent during slow-wave sleep, often considered the deepest stage of sleep. Brain imaging during slow-wave sleep showed that the scent cue activated the hippocampus, a region linked with memory. Scientists at the University of Lübeck in Germany and their colleagues present their findings in the March 9 Science.