The effects of aromatherapy essential oil inhalation on stress, sleep quality and immunity in healthy adults: Randomized controlled trial

IntroductionStress can lead to poor sleep and compromise immune function and it is important to identify approaches that can address such problems and improve quality of life. The aim of this randomized controlled trial was to examine whether aromatherapy via inhalation of essential oils could relieve perceived stress, depression, and improve sleep quality, and immune function.MethodsSubjects aged 20-60 years responding to a recruitment advertisement posted in a general hospital were randomly assigned into either an aromatherapy group (n = 30) or a waiting list control group (n = 30). The subjects in the experimental treatment were asked to inhale an essential oil blend of lemon, eucalyptus, tea tree, and peppermint in a ratio of 4:2:2:1. The essential oil blend was inhaled by wearing a pendant during the day and sleeping near an aromatherapy stone at night for four weeks. Perceived stress, stress index, autonomic nervous system (ANS) activation, and glycated hemoglobin (HbA1c) levels were measured to examine stress. In addition, depression was measured using the Center for Epidemiologic Studies Depression Scale (CES-D). Sleep quality and immune state were also measured.ResultsThe aromatherapy group had significantly lower perceived stress levels (p < 0.001) and depression (p = 0.049) and significantly higher sleep quality (p = 0.001), but the two groups did not differ in terms of ANS activation, HbA1c levels, or immune status.ConclusionsIn conclusion, inhalation of essential oils as per aromatherapy, resulted in lower perceived stress and depression, as well as better sleep quality, but did not influence physiological parameters, such as the stress index or immune state.