According to the World Health Organization , approximately 450 million people worldwide have some form of mental or behavioral disorder. One such disorder is anxiety, which is an emotional state that develops in response to real or imaginary threats and accordingly can be realistic or psychological . A psychological crisis negatively affects daily activities and increases the risk for other disorders . Anxiety disorders are among the most common forms of psychopathology worldwide , and the prevalence of anxiety as a medical condition has increased in recent years . Since ancient times, essential oils of many plants, such as orange blossom, lemon balm, jasmine, and lavender, have been used in aromatherapy for their calming effects . In recent decades, results of several scientific studies conducted in animals and humans have supported the use of these oils for psychoactive effects .