This investigation's objective was to ascertain the effects of Lavandula angustifolia aromatherapy oil on patients undergoing neurological rehabilitation in terms of sleep quality and anxiety levels. It was also aimed to analyze the composition of L. angustifolia oil used in aromatherapy. Material and Methods: Forty-two adults with a diagnosis of spinal cord injury or stroke receiving neurological rehabilitation as inpatients were included in the study and used aromatherapy L. angustifolia oil through inhalation from the inner side of the wrist for 30 days to relieve their anxiety disorders and sleep problems. The Pittsburgh Sleep Quality Index (PSQI) was used to measure the patients' sleep quality, and the Beck Anxiety Inventory (BAI) was used to measure their anxiety levels before and 30 days after the application. Additionally, methods using gas chromatography-mass spectrometry and solid-phase microextraction were utilized to investigate the chromatographic analysis of the used L. angustifolia oil. Results: Comparisons were made between calculated and reported percentages of the remaining constituents, which included eucalyptol, terpinolene, lavandulol and ci, and, as well as the two primary volatile compounds found in L. angustifolia, linalyl acetate (27.69%) and linalool (29.33%). Conclusion: According to our research, the patients' PSQI and BAI ratings showed a statistically significant improvement after 30 days of L. angustifolia oil aromatherapy application. Therefore, it is considered that L. angustifolia oil aromatherapy can be recommended in patients with sleep and anxiety problems during the neurological rehabilitation process, but there is a need for further comprehensive randomized controlled trials on this subject.