Volatiles emitted from the leaves of Laurus nobilis L. improve vigilance performance in visual discrimination task.

ABSTRACT

The leaves of Laurus noblis L. (laurel) are mainly used as a spice in cooking, and the essential oil obtained by steam distillation of the leaves is used as an additive in foods, drugs and cosmetics. We investigated the effect of the volatiles emitted from the leaves of L. noblis at different doses (low-dose and high-dose groups) on vigilance performance in a visual discrimination task. By inhaling volatiles of the leaves of L. noblis, the decrease of the rate of true hits found in the control group was prevented in the low-dose group. The high-dose group showed higher scores than the low-dose group for subjective effects related to negative emotion. Meanwhile, both groups showed physiological effects suggesting stimulation of circulation. These findings suggest that the volatiles emitted from the leaves of L. noblis at low concentration could be utilized to maintain a high level of vigilance performance, such as the rate of true hits by improving physiological arousal without incurring the detrimental performance effects of negative emotion.