Effects of Tilia tomentosa on sleep architecture and circadian rhythm

Tilia extract has been used for centuries as a sedative and hypnotic compound. The impact of Tilia on sleep architecture and circadian rhythm remained, however, elusive. Here, we addressed these open questions by analysing the behaviour and the EEG signals recorded in freely moving mice fed an enriched diet with Tilia extracts. We found that Tilia significantly increased the amount of sleep, mostly during the dark hours, which correspond to the most active phase in nocturnal animals, such as mice. Furthermore, in darkness, the length of wake episodes did not increase as in controls. Spectral analyses of the EEG showed that the features of the sleep and wake signals remained unaltered upon Tilia treatment. Interestingly, the power in the gamma band resulted significantly decrease while the theta band power resulted increased in treated mice. Altogether, our data demonstrated a clear effect of Tilia on sleep architecture, highlighting its dependency on the circadian rhythm.