The Pendulum of Sleep

Who among us hasn't dreamed of sleeping longer and finally getting a good night's sleep? Humans are the only creatures on Earth who can afford to sleep eight hours... but it's not very healthy. At the same time, most of our insomniacs are imaginary, and the melatonin that is used to fight them doesn't help. There are some things we already know about sleep. For instance, we have phases of slow and fast sleep, thanks to their alternation, a person is able to think and, in principle, to exist. And the main questions: what does the brain do at sleep? Why do we dream? How does a REM sleep occur? still remain unanswered. The scientific search this makes all the more interesting.