Abstract
Study objectives: The goal of this study was to clarify whether ginseng fermented by lactic acid bacteria (fermented ginseng, FG), can improve the first-night effect (FNE) in humans. Design: Behavioral tests and quantification of mRNA expression related to GABAergic neurotransmission in brain (glutamic acid decarboxylase 1, gamma-aminobutyrate aminotransferase [Abat], gamma-aminobutyric acid transporter 1 [GAT1], gamma-aminobutyric acid transporter 4, gamma-aminobutyric acid A receptor subunit alpha 1 and gamma-aminobutyric acid A receptor subunit alpha 2) were carried out in FG-treated mice. We also performed double-blind sleep recordings of human subjects given FG or placebo. Setting: A university-based sleep laboratory. Patients or participants: Sixteen healthy male volunteers (aged 20.69 +/- 0.44 years) were observed in the human study. Interventions: At the end of administration, 2 consecutive all-night polysomnography recordings were performed. Subjects also completed psychological questionnaires, and urine and saliva samples were taken to analyze stress-sensitive markers. Measurements and results: The light-dark transition test demonstrated that FG had some anxiolytic effect in mice, but other anxiety measures were unaffected. The hippocampal mRNA expression showed a decrease of Abat and GAT1 suggesting an increase of GABA. Other regions (amygdala and cerebellum) showed no differences. Furthermore, there was some evidence (using simple pairwise comparisons but not supported in the full ANOVA model) that administration of FG tended to diminish decreases in total sleep time and sleep efficiency (seen as first night effects in the placebo group) without affecting sleep architecture. Conclusions: Our results suggest the administration of FG could improve the FNE in humans. The improvement may be related to an anxiolytic effect of FG which acts via GABAergic modification.