Olfactory cues, like a rose scent, paired with learning during wakefulness and re-exposed during sleep, can enhance memory consolidation.

“what they did was they had them learn this kind of Pur associate card test but they were wearing this Mass almost looks like a fighter pilot mask and they were either puffing up inert air that was that didn't smell at all or they were perusing this very pleasant Rose scent because smell in particular has a very unique relationship with our memory in part because we emerged you know from animals that would principally use smell as their navigational tool I think everyone has had this experience where you Bond a certain cologne or a certain perfume with a particular individual so they were puffing The Rose perfume up the nose of these participants and then when they went into sleep they started to reperfuse that Rose odor”

“another group did had learning but they had no rose smell pushed up their nose to bond with the information at the time of learning when they were awake and then when they slept they also had Rose odor stuffed up their nose and they showed no additional benefit so it's not just enough to have Rose odor at night you need to have made the initial bonded familiar connection with the novel information that you're learning to get the subsequent targeted memory reactivation benefit”