This study is a three-group, parallel, randomized controlled clinical trial that aims to compare the effects of melatonin tablets and orange blossom water on sleep quality and preoperative anxiety in patients aged 18 to 65 years who are candidates for elective surgery. Convenient sampling will be performed from patients referring to Besat, Shahid Beheshti, and Ekbatan educational and medical centers. The sample size is 105 people (35 people in each group), and the allocation of individuals to three groups of melatonin, orange blossom water, and placebo will be done using a block randomization method and using sealed and coded envelopes. The intervention will be performed the night before surgery; the melatonin group will receive 5 mg of oral melatonin, the orange blossom water group will receive 15 ml of standard industrial orange blossom water, and the control group will receive the same placebo.Data will be collected using a researcher-made checklist, Spielberger Anxiety Questionnaire, and Chen Sleep Quality Questionnaire on the day of admission (before the intervention) and on the morning of the operation. Inclusion criteria include no history of mental illness, no sensitivity to the intervention, no use of sedatives or hypnotics in the past month, and no severe heart, liver, or kidney diseases. The study is conducted with the approval of the Ethics Committee of Hamadan University of Medical Sciences and the license of the relevant medical centers.