Background: Although aromatherapy is considered an adjuvant therapy to promote sleep quality, few objective sleep testing instruments can confirm the effects of aromatherapy on sleep physiology. The purpose of this study was to confirm and compare the immediate effects of a single lavender essential oil (SLEO) group to a complex lavender essential oil (CLEO) group by objective polysomnography (PSG) recordings.

Methods: Participants were randomly divided into the SLEO group and CLEO group in this single-blind trial to explore the sleep effect of essential oil aroma. All the participants completed the sleep-related questionnaires and underwent two consecutive nights of PSG recordings, who had one night without aromatherapy and one night with one of the two aromas randomly assigned to them.

Results: Total of 53 participants were recruited for this study, 25 participants were in the SLEO group, and 28 were in the CLEO group. Baseline characteristics and sleep-related questionnaires were similar in both groups. Both SLEO and CLEO extended the total sleep time (TST) (Δ = 43.42 and 23.75 minutes, respectively) and sleep period time (SPT) (Δ = 38.86 and 24.07 minutes, respectively). The SLEO group further improved sleep efficiency and increased the amounts of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep and decreased spontaneous arousals. However, there was no significant difference in PSG parameters between the SLEO and CLEO groups.

Conclusion: Both SLEO and CLEO extended TST and SPT, with no significant differences between these two groups. These results warrant practical applications and merit future studies (Clinical trial registration: ClinicalTrials.gov : NCT03933553).