Stress refers to the state of psychological, physiological and physical strain that is felt when one is faced with an environment that is difficult to adapt to [1]. Chronically, it may lead to physical diseases such as heart disease, stomach ulcers, hypertension, etc. and psychological maladaptation including insomnia, neurosis, depression. Acutely, psychological changes such as anxiety may appear or physiological changes such as release of catecholamine, increase in blood pressure due to the activation of the sympathetic nervous system, and increase in pulse rate may appear [1], [6] and [7]. Particularly from a medical perspective, stress can be the cause of many diseases, and relieving stress is one of the most basic responsibilities of the medical staff since hospitalizations and surgeries may induce stress [1]. Particularly in the medical field, efforts to relieve stress are in progress as the number of diseases caused by stress increases while diseases and treatment may be a source of stress themselves [1] and [8].
Aromatherapy is the therapeutic use of essential oils from plants. Essential oils can be absorbed into the body via the skin or the olfactory system [9]. Recent systematic review showed that aromatherapy is one of popular complementary and alternative medicine in UK [10]. Several textbooks have also asserted the favourable therapeutic effects of aromatherapy for psychological health including stress management [9], [11] and [12]. One overview suggested that aromatherapy, which generally delivered with massage therapy, may induce relaxation which, in turn, might improve pain and psychological health [13]. There are three systematic reviews of aromatherapy for psychological health including anxiety and depression [14], [15] and [16]. One of them includes 16 RCTs and suggested beneficial effects on reducing anxiety [14]. The other systematic review that was based on 13 RCTs showed limited evidence of anxiolytic effects of lavender . Third systematic review included six studies of aromatherapy for depression and suggested beneficial effects . However, no systematic reviews for stress reduction are currently available.
The aim of this systematic review was to summarise and critically assess the evidence from randomised clinical trials for or against the effectiveness of aromatherapy as an anti-stress treatment.