Electroencephalogram tests have shown that brain waves change in response to different smells and what we sniff can affect the central nervous system and even alter mood. [...] What’s harder to quantify is whether or not a specific scent can reliably trigger a physiological benefit or conjure the same specific emotion for everyone—and if it can do so when combined with other aromas, as in a fine fragrance.
— Read more at Aromatherapy Perfumes: Do They Really Work? at Marie Claire.