There is a growing demand for natural sleep aids due to various side effects of long-term administration of pharmacological treatments for insomnia. Honey has been reported to exhibit numerous potential health benefits, and it is hypothesized that honey may favorably affect insomnia treatment. Therefore, this study was performed to investigate the possible hypnotic effect of clover honey (CH) and to determine its in vivo mechanism. The total flavonoid content (TFC) of CH and fractions extracted with ethylacetate (EtOAc) and H2O was measured. The pentobarbital-induced sleep test using GABAA-benzodiazepine (BZD) agonists and antagonists was conducted to evaluate the potential mechanism of action behind the sedative-hypnotic activity of CH in mice. The results showed that administration of 500 and 1,000 mg/kg of CH significantly (p<0.01) reduced the sleep latency to a level similar to that of diazepam (DZP, 2 mg/kg), and 1,000 mg/kg of CH significantly (p<0.01) prolonged the sleep duration, which was comparable to that of DZP (2 mg/kg). Administration of the EtOAc fraction with a higher TFC significantly reduced the sleep latency at 50 to 200 mg/kg and prolonged the sleep duration at 100 to 200 mg/kg, which were comparable to those after administration of DZP (2 mg/kg). However, co-administration of CH and EtOAc with flumazenil, a specific GABAA-BZD receptor antagonist, blocked the hypnotic effect. Our findings suggest that the hypnotic activity of CH may be attributed to allosteric modulation of GABAA-BZD receptors. The TFC of CH is expected to be a key factor that contributes to its hypnotic effect.

Introduction
 Materials and Methods
  1. Materials and drugs
  2. Preparation of honey fractions
  3. Determination of total flavonoid content (TFC)
  4. Animals
  5. Pentobarbital-induced sleep test
  6. Statistical analysis
 Results
  1. Effect of CH on sleep latency and duration
  2. Effect of the EtOAc fraction on sleep latency andduration
  3. Effect of FLU on changes in sleep latency and sleepduration
 Discussion
 Acknowledgement
 References

• Kyoung-Sik Han(Dept. of Food Science and Biotechnology, Graduate School, Sahmyook University) Corresponding author
• Hyejin Yang(Korea Food Research Institute)
• Minseok Yoon(Korea Food Research Institute)