I did some research in peer-reviewed scientific journals about the efficacy (effectiveness) of aromatherapy as a treatment for anxiety and depression. Most of the articles I read seem to support it as a complementary treatment – that is, to be used along with traditional treatments such as psychotherapy and medication. There is a need for research that 1) separates the effects of aromatherapy from that of massage and 2) examines the relative efficacy of specific essential oils. Lavender is an essential oil that might help with anxiety, depression, and sleep disorder.
Here are my notes on three review articles:
A review of 16 studies from 1990 to 2010 found that aromatherapy can safely be used as a complementary therapy to reduce anxiety (Lee, et al, 2011). More research is needed to understand how best to implement it (e.g. massage or inhalation) and why it works biologically.
A review of 6 studies from 2000 to 2008 found that aromatherapy-enhanced massage can safely be used to improve mood in people with depressive symptoms (Yim, et al, 2009). A substance found in essential oils, citral, “produces relaxation and antidepressant effects” (192). It is unclear whether particular essential oils are more effective than others; additional research is needed.
Perry & Perry (2006) examine use of aromatherapy in a variety of disorders, including sleep disorder, anxiety, and depression.
Sleep Disorder – “In one study, a blend of basil, juniper, lavender, and sweet marjoram was applied by hand massage; satisfactory sleep increased from 73% to 97% of patient nights […]” (264). Lavender is the essential oil most discussed in the treatment of sleep disorders.
Anxiety – There is limited support for use of aromatherapy to treat anxiety, but of the essential oils, lavender seems most promising.
Depression – There is some support for the use of chamomile, citrus, and lavender. Controlled trials are needed to confirm efficacy.
For more information about aromatherapy, including safety and quality information, visit the National Association for Holistic Aromatherapy.
References
Lee, Y., Wu, Y., Tsang, H.W.H., Leung, A.Y.., & Cheung, W.M. (2011). A systematic review on the anxiolytic effects of aromatherapy in people with anxiety symptoms. The Journal of Alternative and Complementary Medicine, 17 (2), 101-108.
Perry, N. & Perry, E. (2006). Aromatherapy in the management of psychiatric disorders: Clinical and neuropharmacological perspectives. CNS Drugs, 20 (4), 257-280.
Yim, V.W.C., Ng, A.K.Y., Tsang, H.W.H., & Leung, A.Y. (2009). A review on the effects of aromatherapy for patients with depressive symptoms. The Journal of Alternative and Complementary Medicine, 15 (2), 187-195.
a day with depression 
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