Modification of brain waves and sleep parameters by Citrus reticulata Blanco. cv. Sai-Nam-Phueng essential oil

Background: Citrus essential oil (EO) has been used for mood elevation and sedative hypnotic purposes. However, scientific proofs of its central nervous system (CNS) action remained largely unexplored. This study investigated chemotypes, electrical brain waves and sleep-wake effects of the essential oil from Citrus reticulata in rat model. Methods: Chemical contents of citrus EO were analyzed using gas chromatography-mass spectrometry (GC-MS). Male Wistar rats implanted with electrodes on the frontal and parietal skulls were used for electroencephalographic (EEG) recording while inhaling the citrus EO (200 ml on cotton wool). Diazepam (10 mg/kg, p.o.) was used as a standard anxiolytic drug. EEG frequency analyses were performed by using Fast Fourier transform. All data were statistical analyzed using One-way ANOVA followed by Tukey's test. Results: GC-MS analysis revealed D-limonene (95.7%) as a major constituent of citrus EO. The EEG results showed that overall EEG patterns of citrus EO effects were relatively similar to that of diazepam. However, significant differences between treatments were seen from sleep-wake analyses. Diazepam significantly increased episode numbers of awake and non-rapid eye movement (REM) sleep and reduced averaged episode duration. On the other hand, the citrus EO significantly decreased REM sleep latency and increased total time and episode numbers of REM sleep. Conclusion: These findings demonstrated unique CNS effects of C. reticulata EO with EEG fingerprints and sleep-wake profiles. The data might be useful for citrus essential oil subclassification and clinical application.

Automated summary

The study explored the chemical components and effects of Citrus reticulata essential oil on brain waves and sleep patterns in rats. D-limonene was identified as the major constituent, and although the EEG patterns were similar to diazepam, differences were seen in sleep-wake analyses. Citrus EO reduced REM sleep latency and increased total time and episode numbers of REM sleep. These findings demonstrated unique CNS effects of Citrus reticulata EO with potential clinical applications.