Favorite odor induces negative dream emotion during rapid eye movement sleep.
Sleep Medicine July 1, 2018 Satomi Okabe, Kazuhiko Fukuda, Hiroko Mochizuki-Kawai et al.
People who liked the rose-like smell of phenyl ethyl alcohol reported more emotionally negative dreams when that odor was presented during REM sleep compared to odorless air. The study presented either the odor or plain air to 15 participants who either liked or disliked the scent, then woke them to report and rate dream content. Individual preference mattered: a favorite odor was linked to negative dream emotions, possibly due to how the brain processes smells during REM sleep.