Effects of Inhaled Aromatherapy on Sleep Quality and Cognitive Function in Older Adults: A Randomized Controlled Trial

BACKGROUND: Sleep disturbances and cognitive decline frequently coexist in older adults and are associated with adverse health outcomes. Aromatherapy has emerged as a potential non-pharmacological intervention; however, evidence from inhalation-based protocols integrating both subjective and objective sleep assessments remains limited. METHODS: This single-blind, randomised controlled trial was conducted in a residential care facility in Istanbul between January and June 2024. Sixty participants aged ≥65 years were randomly allocated to an intervention group (n = 30) or a control group (n = 30). The intervention consisted of inhaling a peppermint-palmarosa blend in the morning and a nighttime blend of vetiver, cedarwood, clary sage, petitgrain, and grapefruit oils for 10 minutes daily over 30 days. Outcomes included the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and Blessed Orientation-Memory-Concentration Test, alongside objective sleep parameters obtained from Oppo Watch Free wearable smartwatches using photoplethysmography and accelerometer-based algorithms. RESULTS: Compared with the control group, the intervention group demonstrated significant improvements in total sleep time (d = 1.29), REM sleep duration (d = 1.34), and deep sleep (N3) duration (d = 1.47), along with reduced sleep latency (d=-1.12) (all p < 0.001). Daytime sleepiness decreased, and subjective sleep quality improved. Cognitive performance also improved, with significant gains observed in orientation, memory, and concentration, whereas no significant changes were observed in the control group. CONCLUSIONS: A circadian-aligned, multi-component inhalation aromatherapy protocol may represent a feasible and clinically relevant complementary intervention to improve sleep architecture and cognitive outcomes in older adults residing in residential care settings.