The effects of lavender volatile inhalation on human behaviour and emotions are not reproducible, because several types of lavender essential oils are available in markets. The aim of this study was to determine the key volatile components for the sedative effect of lavender essential oil on human. We tested twenty-seven Lavandula essential oils and analysed their volatile component compositions by means of GC and GC-MS. Volatile component composition of the essential oils was categorized by Principal Components Analysis and seven essential oils were selected for physiological/psychological evaluation. Power spectral analysis on R–R intervals, salivary amylase activity and POMS test showed that some essential oils showed sedative effects on humans. Oils with stimulant effects were also observed. Differences in volatile composition between sedative and stimulant oils suggested that key components of aromachology effects of Lavandula oils were linalyl acetate (sedative effect) and camphor (stimulant effect).