There is much scientific research on this topic. Several human studies across a wide variety of settings with a diverse array of populations have demonstrated the calming effects of inhaling lavender aroma. Lavender aromatherapy has shown to lower blood pressure and relax the sympathetic nervous system. Studies have also measured a positive effect on mood: reducing depression, anxiety, and stress through the inhalation of this essential oil. The active constituent(s) demonstrating a calming effect are linalool [1] [2], and a synergistic effect of linalool in combination with linalyl acetate.[3] The activation of serotonergic neurotransmission in the brain may play a role in lavender’s anxiolytic properties.[4]
Find more research on calming herbs.
References
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[2] Elisabetsky, E., Marschner, J., & Souza, D. O. (1995). Effects of linalool on glutamatergic system in the rat cerebral cortex. Neurochemical research, 20(4), 461-465.
[3] Takahashi, M., Satou, T., Ohashi, M., Hayashi, S., Sadamoto, K., & Koike, K. (2011). Interspecies comparison of chemical composition and anxiolytic-like effects of lavender oils upon inhalation. Natural product communications, 6(11), 1769-1774.
[4] Takahashi, M., Yamanaka, A., Asanuma, C., Asano, H., Satou, T., & Koike, K. (2014). Anxiolytic-like effect of inhalation of essential oil from Lavandula officinalis: investigation of changes in 5-HT turnover and involvement of olfactory stimulation. Natural product communications, 9(7), 1023-1026.
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[27] MPham, W. S., & Siripornpanich, V. (2012). The effects of lavender oil inhalation on emotional states, autonomic nervous system, and brain electrical activity. J Med Assoc Thai, 95(4), 598-606.
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[29] Kim, M. J., Nam, E. S., & Paik, S. I. (2005). The effects of aromatherapy on pain, depression, and life satisfaction of arthritis patients. Taehan Kanho Hakhoe Chi, 35(1), 186-194.
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[40] Saeki, Y. (2000). The effect of foot-bath with or without the essential oil of lavender on the autonomic nervous system: a randomized trial. Complementary Therapies in Medicine, 8(1), 2-7.
[41] Gedney, J. J., Glover, T. L., & Fillingim, R. B. (2004). Sensory and affective pain discrimination after inhalation of essential oils. Psychosomatic Medicine, 66(4), 599-606.
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[43] Xu, F., Uebaba, K., Ogawa, H., Tatsuse, T., Wang, B. H., Hisajima, T., & Venkatraman, S. (2008). Pharmaco-physio-psychologic effect of Ayurvedic oil-dripping treatment using an essential oil from Lavendula angustifolia. The Journal of Alternative and Complementary Medicine, 14(8), 947-956.