AROMATHERAPY VS. SOUND THERAPY: A NARRATIVE REVIEW OF NON-PHARMACOLOGICAL INTERVENTIONS FOR INSOMNIA

Abstract

Background: Insomnia is among the most prevalent sleep disorders worldwide, affecting 10–30% of adults and imposing substantial individual and societal burdens. While pharmacological treatments offer short-term relief, concerns regarding dependence, tolerance, and adverse effects have fueled demand for non-pharmacological alternatives. Aromatherapy and sound therapy represent two accessible, low-cost, sensory-based modalities with growing evidence for sleep improvement; however, no comprehensive review has directly compared their mechanisms, clinical evidence, and applicability. Objective: This narrative review aims to comprehensively compare aromatherapy and sound therapy as non-pharmacological interventions for insomnia, examining their neurobiological mechanisms, clinical evidence, safety profiles, and potential for integration into clinical practice. Methods: A narrative synthesis was conducted using PubMed, Scopus, CINAHL, and the Cochrane Library, covering publications from 2000 to 2025. Eligible sources included randomized controlled trials (RCTs), systematic reviews, meta-analyses, and mechanistic studies addressing aromatherapy or sound-based interventions for insomnia in adults. Key outcome measures included the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), sleep onset latency, and total sleep time. Results: Both modalities demonstrated clinically meaningful improvements in sleep outcomes. Aromatherapy, particularly lavender inhalation, yielded significant reductions in PSQI scores across meta-analyses (mean difference approximately −2.3 points), mediated by olfactory-limbic activation, GABA-A receptor modulation, and autonomic nervous system (ANS) downregulation. Sound therapy, encompassing slow-tempo music, pink noise, and binaural beats, similarly improved sleep quality (meta-analysis weighted mean difference −2.0 to −2.8 on PSQI) via auditory-limbic entrainment and parasympathetic activation. Despite different sensory entry points, both pathways converge on the limbic system and ANS to reduce the hyperarousal central to insomnia pathophysiology. Safety profiles are favorable for both, with aromatherapy carrying slightly higher risk of allergic reactions and drug interactions. Conclusion: Aromatherapy and sound therapy are complementary, evidence-based adjuncts to first-line cognitive behavioral therapy for insomnia (CBT-I). Selection should be guided by patient profile, preferences, and safety considerations. A dual-sensory convergence model is proposed to explain the shared limbic mechanism underlying both interventions. Direct head-to-head randomized trials and studies with objective sleep endpoints are needed to further delineate their respective roles.