ABSTRACT Sleep disturbances, particularly insomnia, represent a growing global health concern with significant consequences for physical, cognitive and mental well‐being. Although conventional pharmacological sleep aids are effective in the short term, their long‐term use is often limited by adverse effects, tolerance, dependence and safety concerns, prompting increased interest in complementary and alternative approaches. Aromatherapy, especially the use of essential oils, has gained popularity as a low‐risk and accessible strategy to improve sleep quality. While numerous reviews have summarized the clinical benefits of whole essential oils, the specific chemical constituents responsible for their sleep‐promoting effects have not been comprehensively examined. This narrative review focuses on the major bioactive constituents found in essential oils and evaluates their potential roles as alternative sleep aids. We synthesize recent experimental and clinical evidence on key classes of compounds, including monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpenes and related aromatic constituents, highlighting their reported effects on sleep quality, anxiety reduction and stress modulation. Proposed mechanisms of action, particularly interactions with inhibitory neurotransmitter systems and autonomic regulation, are also discussed. In addition, this review addresses practical applications, safety considerations, population‐specific recommendations and current limitations related to variability in essential oil composition and the lack of standardized clinical data. By shifting the focus from whole oils to individual constituents, this review aims to support rational product development, quality control and evidence‐based use of essential oil–derived compounds in future sleep aid formulations.
Seephan et al. (2026) studied this question.