In the article "Twinkling, star-shaped brain cells may hold the key to why, how we sleep". It's amazing how little we know about sleep. It turns out that transitioning to sleep involves cellular calcium signaling.
“The findings of this study suggest that we may have been looking in the wrong place for more than 100 years," said senior author and professor of biomedical sciences Marcos Frank. "It provides strong evidence that we should be targeting astrocytes to understand why and how we sleep, as well as for the development of therapies that could help people with sleep disorders and other health conditions that involve abnormal sleep."