Abstract

   Agarwood, a precious traditional medicinal herb and fragrant material,
   is known for its sedative and sleep-improving properties. This study
   explores the mechanisms underlying the aromatherapy effects of Chi-Nan
   agarwood and ordinary agarwood in improving sleep. Using a combination
   of gas chromatography–mass spectrometry (GC-MS), network pharmacology,
   and molecular docking techniques, we identified and c ompared the
   chemical compositions and potential molecular targets of both types of
   agarwood. The GC-MS analysis detected 87 volatile components across six
   types of agarwood aromatherapy, with 51 shared between Chi-Nan and
   ordinary agarwood, while each type also had 18 unique components.
   Ordinary agarwood was found to be richer in sesquiterpenes and small
   aromatic molecules, whereas Chi-Nan agarwood contained higher levels of
   chromones. These differences in chemical composition are likely
   responsible for the distinct sleep-improving effects observed between
   the two types of agarwood. Through network pharmacology, 100, 65, and
   47 non-repetitive target genes related to sleep improvement were
   identified for components shared by both types of agarwood (CSBTs),
   components unique to common agarwood (CUCMs), and components unique to
   Chi-Nan agarwood (CUCNs), respectively. The constructed protein–protein
   interaction (PPI) networks revealed that key targets such as MAOA,
   MAOB, SLC6A4, and ESR1 are involved in the sleep-improving mechanisms
   of agarwood aromatherapy. Molecular docking further confirmed the
   strong binding affinities of major active components, such as
   5-Isopropylidene-6-methyldeca-369-trien-2-one and
   2-(2-Phenylethyl)chromone, with these core targets. The results suggest
   that agarwood aromatherapy enhances sleep quality through both hormonal
   and neurotransmitter pathways, with ordinary agarwood more deeply
   mediating hormonal regulation, while Chi-Nan agarwood predominantly
   influences neurotransmitter pathways, particularly those involving
   serotonin and GABA. This study provides valuable insights into the
   distinct therapeutic potentials of Chi-Nan and ordinary agarwood,
   highlighting their roles in sleep improvement and offering a foundation
   for future research in the clinical application of agarwood-based
   aromatherapy.

   Keywords: agarwood, aromatherapy, network pharmacology, sleep aid,
   molecular docking, bioinformatics

1. Introduction

   Insomnia, characterized by difficulty in falling or staying asleep, has
   become a prevalent clinical issue in modern society. It is often
   triggered by various factors, including emotional stress and
   occupational demands, leading to a significant number of individuals
   suffering from poor sleep quality [[34]1]. The traditional clinical
   approach to managing insomnia involves the use of sedative–hypnotic
   drugs. However, these medications are often accompanied by adverse side
   effects, including drug dependence, tolerance, withdrawal symptoms, and
   even potential rebound insomnia upon discontinuation [[35]2,[36]3]. As
   a result, there is a growing interest in finding safe and effective
   alternatives to pharmacological treatments for sleep disorders.

   Agarwood, known for its unique and valuable fragrance, has been
   utilized for centuries in traditional medicine and aromatherapy across
   various cultures. Often referred to as the “king of incense,” agarwood
   is highly prized in regions such as China, the Middle East, Europe, and
   the United States for its therapeutic properties [[37]4]. Historically,
   agarwood was used [[38]5] in China as early as the Sui and Tang
   dynasties, where it was burned in court settings to signify solemnity
   and respect [[39]6]. Today, with advancements in cultivation and
   processing technologies, agarwood is broadly categorized into two main
   types: ordinary agarwood and Chi-Nan agarwood [[40]7]. These two
   varieties of agarwood exhibit distinct aromatic profiles and are
   believed to offer different therapeutic benefits, particularly in terms
   of calming the mind and improving sleep [[41]8].

   Previous studies have suggested that agarwood aromatherapy has a
   sedative effect, potentially aiding in sleep improvement by influencing
   neurotransmitter levels and neural activity. In our preliminary animal
   experiments, we found that the inhalation of agarwood incense
   significantly inhibited the spontaneous activity of insomnia-induced
   mice, effectively improving their sleep conditions. The mechanism of
   action may be related to the regulation of 5-HT neurotransmitter levels
   in the brain, balancing GABA-Glu secretion, and the synthesis,
   metabolism, and transport of Glu [[42]3,[43]9,[44]10]. Despite these
   insights, there remains a lack of comprehensive understanding regarding
   the specific mechanisms through which Chi-Nan agarwood exerts its
   sleep-promoting effects.

   To address this gap in knowledge, the current study aims to explore the
   similarities and differences between Chi-Nan agarwood and ordinary
   agarwood in improving sleep quality. By employing a combination of gas
   chromatography–mass spectrometry (GC-MS) for chemical analysis and
   network pharmacology, the study seeks to identify the active components
   of these agarwood varieties and elucidate their mechanisms of action.
   This research will provide important references for the clinical