New research confirms that scents we smell as we learn and sleep influence our cognitive performance. Neumann, Oberhauser, and Kornmeier conducted a field study with sixth graders anddetermined that when people smelled the same scent when learning material and later while sleeping (scent was present all night) that they remembered the learned material better after waking up. The scent used by researchers was of roses.
Franziska Neumann, Vitus Oberhauser, and Jorgen Kornmeier. 2020. “How Odor Cues Help to Optimize Learning During Sleep in a Real Life-Setting.” Scientific Reports, vol. 10, no. 1227, https://www.nature.com/articles/s41598-020-57613-7