Cool, fresh and invigorating, top notes, such as citrus oils, only last a short time and can enhance concentration. Rose, Jasmine and other flower oils along with woodsy or spicy scents are heart notes. Known to harmonize and balance, they’re also sensually stimulating and last longer than the top notes. The longest lasting, base notes such as Vetiver are relaxing and grounding. They often come from roots or resinous oils.