Modern medicine has proved that people who go to bed early and get up early have less mental stress and are less prone to mental illness. Don't go out to exercise too early in the morning, because before the sun comes out in the morning, the air and turbidity of underground tunnels are rising (especially in cities), which is very harmful to human body.
Fitness has three elements, one is sleep, the other is convenience, and the third is diet. The rest of the daily life and clothes are auxiliary. Sleep is the first of three things. But if the stomach is not harmonious, you will feel uneasy at night, so convenience is second. And those who eat without restraint and are too hungry will have stomach injuries and their nutrition will decrease day by day. Sleep is mainly about calming the nerves, and the mind is mainly about peace of mind. Should be suitable for age, the maximum age is seven to eight hours. If you sleep too much, you will feel dizzy, your eyes will be red, and your limbs will be weak. When you were a child, you will sleep for eight hours, or you will be fine after nine hours. For the elderly or patients, six hours at most is enough.
For health! Try to go to bed early and stay up late, which will hurt the yang. The next day will inevitably be tired and weak. You should close the window and don't turn on the air conditioner and electric fan to protect the yang.
As for the book you want, I think it's better to read "Zhigang's Blog-Teach You How to Sleep" first.