Aromatherapy has gained attention as a potential non-invasive aid for better sleep, especially among adults and the elderly. A recent meta-analysis of 30 studies found that aromatherapy significantly improved sleep quality, with a moderate overall effect size of 0.74 (Her & Cho, 2021). Benefits were most pronounced in East Asian populations, quasi-experimental trials, and aroma massage interventions, with effect sizes above 1.0.

Importantly, sleep quality improved across various formats, including short-term use (under 4 weeks) and sessions longer than 20 minutes. These improvements extended beyond sleep, also reducing stress, pain, anxiety, depression, and fatigue.

Complementing these findings, a pilot EEG study in Taiwan explored the objective neural effects of lavender aroma during sleep (Ko et al., 2021). In this single-blinded experiment, nine healthy young adults unknowingly received lavender aroma during one of two sleep sessions.

Despite not detecting the scent consciously, participants showed notable changes in EEG readings: increased delta waves - linked to deep sleep - and decreased alpha waves, which usually indicate wakefulness or disturbed sleep. Lavender exposure also increased slow-wave sleep (SWS) by over 2%, suggesting enhanced sleep stability and quality.

While both studies show positive outcomes, the pilot EEG study used a small sample size and focused on healthy adults, limiting its generalizability. However, its controlled design strengthens the evidence that lavender aroma can alter brain activity during sleep, supporting earlier behavioral claims with physiological data.