Listening to books, concentration, concentration is easy to get sleepy. The reason why I can't sleep is mostly because I think at random and think a lot. I've been thinking about these things all night. How can I sleep? ! According to science, there should be waves in sleep, one active and the other inactive. We don't care about this, as long as we sleep well. There are two points here: first, falling asleep quickly, and second, the quality of sleep is good. You should ask the first one. I have done experiments. Listen to the longest book 1 half an hour and the shortest 10-20 minutes to fall asleep. As for what the book says, I don't know when I wake up.