A Novel Potent Sleep-Promoting Effect of Turmeric: Turmeric Increases Non-Rapid Eye Movement Sleep in Mice Via Histamine H-1 Receptor Blockade

Scope: Turmeric has a broad spectrum of biological properties; however, the sleep-promoting effects of turmeric have not yet been reported. Thus, this study aims to investigate the effect of turmeric on sleep and the molecular mechanism underlying this effect. Methods and Results: Pentobarbital-induce sleep test and sleep-wake profile assessment using recorded electroencephalography are used to evaluate the hypnotic effects of the turmeric extract (TE) compared to diazepam on sleep in mice. Additionally, the molecular mechanism of TE's sleep effect is investigated using ex vivo electrophysiological recordings from brain slices in histamine H-1 receptor (H1R) knockout mice. Oral administration of TE and diazepam significantly reduce sleep latency and increase non-rapid eye movement sleep (NREMS) duration without delta activity in mice. Like doxepin, TE inhibits the H1R agonist (2-pyridylethylamine dihydrochloride)-induced increase in action potentials in the hypothalamic neurons. In animal tests using neurotransmitter agonists or antagonists, TE effect mimick H1R antagonistic effect of doxepin. Additionally, both reduce sleep latency and increase NREMS in wild-type mice, although these effects are not observed in H1R knockout mice. Conclusion: TE has a sleep-promoting effect owing to reduction in sleep latency and enhancement of NREMS via H1R blockade; therefore, it could be useful in insomnia.