Introduction: The objective of this investigation was to evaluate the effect of Rosmarinus officinalis essential oil on anxiety, depression, and sleep quality. Methods: The essential oils were extracted by hydro-distillation using a modified Clevenger-type apparatus and the chemical composition was performed by Gas chromatography with flame ionization detection (GC-FID) and Gas chromatography mass spectrometry (GC–MS). Furthermore, a quasi-experimental study was conducted, where 81 participants were divided into two groups, comprising a waiting list control group and an experimental group treated with essential oils. Anxiety and depression indexes were evaluated using the Zung Self-Rating Anxiety Scale (SAS) and the Zung Self-Rating Depression Scale (SDS), and sleep quality was measured with the Pittsburgh Sleep Quality Inventory (PSQI). Results: Chemical analysis showed that 1,8 cineo...