A systematic literature review and meta-analysis of the clinical effects of aroma inhalation therapy on sleep problems

Background: This systematic review investigated the clinical effects of inhalation aromatherapy for the treatment of sleep problems such as insomnia. Methods: Studies on sleep problems and inhalation aromatherapy, published in Korean and international journals, were included in the meta-analysis. Five domestic and international databases, respectively each, were used for the literature search. Keywords included sleep disorder, sleep problems, insomnia, and aroma inhalation, and the related literature was further searched. After the screening, selected articles were assessed for their quality and conducted the risk of bias using RevMan 5.0, a systematic literature review was then conducted. A meta-analysis comparing the averages was conducted on studies that reported numerical values. Additionally, meta-analysis of variance and meta-regression analyses were performed. Results: Meta-analysis of the 34 studies using the random-effects model revealed that the use of aromatherapy was highly effective in improving sleep problems such as insomnia, including quantitative and qualitative sleep effects (95% confidence interval [CI], effect sizes = 0.6491). Subgroup analysis revealed that the secondary outcomes including stress, depression, anxiety, and fatigue were significantly effective. The single aroma inhalation method was more effective than the mixed aroma inhalation method. Among the single inhalation methods, the lavender inhalation effect was the greatest. Conclusion: Inhalation aromatherapy is effective in improving sleep problems such as insomnia. Therefore, it is essential to develop specific guidelines for the efficient inhalation of aromatherapy. Ethics and dissemination: Ethical approval is not required because individual patient data are not included. The findings of this systematic review were disseminated through peer-reviewed publications or conference presentations. PROSPERO registration number: CRD42020142120.