Preliminary Clinical Evaluation of Inhalation Aromatherapy with Blended Essential Oils on Sleep Quality in Adults with Sleep Disturbance

Background: Sleep disturbances impact cognition and physiology. While individual essential oils are documented, a gap remains in how multi-component blends can target multiple pathways. This study evaluated a blended essential oil (BEO) systematically guided by Thai Traditional medicine (TTM) principles to balance the "Wind" element (Tard Lom) alongside modern neurobiological validation. Methods: A one-group pretest–posttest quasi-experimental study was conducted in adults (aged ≥ 20 years, n = 38) with sleep disturbances (PSQI > 5). The BEO formulation consisting of orange (2.5% w/w), lavender (1.0% w/w), ylang-ylang (1.5% w/w), geranium (0.5% w/w), cedarwood (2.0% w/w), and rosewood (2.0% w/w) in 95% ethanol (90.5% w/w) was sprayed nightly onto pillows for 14 days. Outcomes were assessed via global/domain PSQI, GC-MS, and in vitro AChE inhibitory assays. Results: GC-MS identified D-limonene (21.17%), linalool (22.38%), and cedryl acetate (1.46%). BEO exhibited concentration-dependent AChE inhibitory activity (IC50 of 0.0164 ± 0.0032 mg/mL; physostigmine: 0.00263 ± 0.00097 mg/mL). Following BEO inhalation, global PSQI scores significantly decreased from 14.76 ± 1.61 to 1.68 ± 1.49 (p < 0.001), with marked improvements across all domains (p < 0.001), including latency, duration, and daytime dysfunction.             Conclusion: Passive BEO inhalation was associated with significant improvements in self-reported sleep quality and daytime functioning. Bioactive profiling and in vitro AChE inhibition support the hypothesized synergistic neurochemical pathways, suggesting BEO as an accessible, non-pharmacological integrative intervention for sleep hygiene. Keywords: Acetylcholinesterase inhibition, Blend of essential oils, Essential oils, Insomnia, Pittsburgh Sleep Quality Index (PSQI), Sleep disturbance, Thai Traditional Medicine