In a 2007 study, for example, a group of neuroscientists had people learn the locations of a bunch of different objects while it smelled like roses, then made it smell like roses again while they were asleep. When they woke up, the subjects were better at remembering where the objects were, compared to when they did the same task without any smells. The researchers proposed that when the subjects smelled roses while they slept, that boosted the memory consolidation process because their brains associated the smell with the memories of the object locations. Basically, the smell acted as a cue to their brains to reactivate those memories, strengthening the connections between the neurons that stored them. And stronger connections meant they had an easier time recalling the memories when they woke up. That 2007 study was small, but later studies that tested the idea found similar results.