α-Asarone: a hypnotic with a potential for long-term use

Commonly used hypnotics are not very effective for the management of chronic insomnia as they produce several unpleasant side effects. According to a recent report, short-term administration of 10 mg/kg α-Asarone, an active principle of Acorus species, used in traditional Indian and Chinese medicine for a prolonged period without any ill-effects, promoted sleep in rats. However, the efficacy of α-Asarone in promoting sleep on long-term use has not been studied. Study was conducted on four groups of rats, with electrodes implanted for recording sleep. Thermocouple and radio-transmitter were implanted for recording temperatures from hypothalamus and peritoneum. Of these, three groups of rats were sleep deprived for 5 h (9:00–14:00 h) for 21 days after drug (α-Asarone or midozolam) or vehicle administration. The anxiety levels were also studied in these rats. Another group, that received α-Asarone for 21 days, was not subjected to sleep deprivation. Long-term administration of α-Asarone improved both the quantity and quality of NREM sleep, not only in comparison to the vehicle, but also in contrast to midazolam. Moreover, there was no withdrawal effect after stopping the daily administration of α-Asarone for 3 weeks. Anxiety alleviation produced by α-Asarone was better than midazolam. α-Asarone-mediated anxiolysis, mild hypothermia, and NREM sleep-related alterations in temperatures, and its known antioxidant property, might have contributed towards the improvement in NREM sleep and maintenance of REM sleep. The study provides strong pre-clinical evidences for further research on α-Asarone as a possible treatment option for chronic insomnia.