Scientists from Tel Aviv University and Israel’s Weizmann Institute have demonstrated that administering certain scents during sleep bolsters memory processes in the brain. The study tested memory recall after using rose scent while memorizing words and then during a short nap.
https://www.israel21c.org/rose-scents-while-you-sleep-can-boost-your-memory/
https://www.cell.com/current-biology/fulltext/S0960-9822(20)30171-8?_return