According to science, ylang-ylang essential oil is a mental stimulant. In contrast, the world of aromatherapy considers this oil one of the best at relaxing the mind and the body. Simply smelling it is supposed to help lower blood pressure. Taking a bath with the oil or using it in a massage oil naturally enhances the relaxation experience. It is used to relieve stress, depression, shock, or anxiety. When used as a hair tonic, it is supposed to balance oil production. Be warned, though, that high concentrations of ylang-ylang can cause headaches or nausea.