Recent research shows that the properties of many oils correspond to the traditionally held views: chamomile, bergamot, sandalwood, lavender, and sweet marjoram were found to have a sedative effect on the central nervous system; jasmine, peppermint, basil, clove, and ylang ylang were found to have a stimulating effect. Neroli was found to be stimulating, and lemon to be sedating, contrary to popular belief. Some oils are known to be 'adaptogens', that is, they have balancing or normalizing effect on the systems of the body: geranium and rosewood were either sedative or stimulating according to each situation and individual.
Words like 'relaxing' and 'uplifting' often have more to do with odour description and emotional response rather than physiological effect - although the two are related. Consequently, oils such as bergamot, lemon balm and lemon can be sedating to the nervous system but reviving to the 'spirit'. But oils such as jasmine, ylang ylang and neroli can be nerve stimulants yet soothing and relaxing on a more subtle emotional level.