Randomization and masking
Participants were randomly assigned to one of the two groups (intervention or control) in a 1:1 ratio, and were double-blinded to ensure that the participants and data analysts in the study could not discriminate between the groups of participants. The permuted block method with block sizes of 2 and 4 was used for randomization assignment. An independent allocation coordinator prepared the aroma and placebo seals, creating an allocation table for each participant, including unique identification codes. Random allocation was conducted by a third party not involved in the study, and allocation results were securely stored in a locked safe. Blinding of intervention providers and data analysts was maintained until the completion of data analysis. Randomization was performed using the R statistical software(version 4.0.2, Foundation for Statistical Computing, Vienna, Austria).