Researchers throughout the world are proving what ancient peoples intuitively knew: Essential oils have powerful effects on the mind and body. John Steele, an aromatic consultant in Sherman Oaks, California, and Robert Tisserand, a leading British aromatherapist, have studied the effects of various essential oils on brain wave patterns. They've shown that beta brain waves, which indicate a state of heightened awareness, are increased when stimulating oils such as black pepper, rosemary, or basil are inhaled. Calming oils such as lavender, and rose produce more alpha and theta brain waves, indicative or relaxation and well-being.
(Source: Herbs for Health: Being Well the Natural Way Magazine, Jan/Feb 2003)