Lavender essential oil fractions alleviate sleep disorders induced by the combination of anxiety and caffeine in mice.

ETHNOPHARMACOLOGICAL RELEVANCE

Lavender (Lavandula angustifolia Mill.) essential oil is renowned for its use in the treatment of insomnia and mental disorder diseases in folk medicine. Previous pharmacological studies have also shown that lavender essential oil displays sedative and hypnotic activities. However, the active ingredients and mechanism of lavender essential oil for sleep-improving effect remain unclear.

AIM OF THE STUDY

This study investigates whether inhalation of different fractions of lavender essential oil can attenuate the sleep disturbances induced by combined anxiety and caffeine and explores the underlying mechanisms.

MATERIALS AND METHODS

Molecular distillation was applied to separate lavender essential oil into fractions containing different chemical components, and GC-MS was used to analyze the volatile compounds of lavender essential oil and its fractions. The elevated plus maze test, pentobarbital-induced sleep test, and neurotransmitters enzyme-linked immunosorbent assay were conducted to evaluate the anxiolytic and hypnotic effects of lavender essential oil and its fractions on mice suffering from sleep disorders.

RESULTS

The results of behavioral tests indicated that lavender essential oil and its fractions (3%, v/v) exerted an ameliorating effect on sleep disturbances induced by anxiety and caffeine. The light fraction and heavy fractions exhibited complementary chemical composition, with the former enriched in linalool and trans-β-ocimene and the latter in linalyl acetate, lavandulyl acetate, trans-caryophyllene, etc. The light fraction contributed more to sleep maintenance, and the heavy fraction performed better at sleep initiation. The neurobiological parameters elucidated that the mechanism of lavender essential oil for sleep-improving was multifaceted, related to the GABAergic system, cholinergic system, histaminergic system, and monoamines in the limbic system. The heavy fraction shared a similar mechanism with the lavender essential oil, while the light fraction did not actively participate in the cholinergic system, histaminergic system, and dopaminergic system.

CONCLUSION

Taken together, our results demonstrated that different fractions of lavender essential oil played different roles in ameliorating sleep disorders, and this may be credited to their compositional differences and the complicated interactions with the central nervous system. The results are informative for future investigations on the molecular level mechanisms and provide guidance for appropriate applications of lavender essential oil.