As I wrote sometimes, I am a little interested in sleep science. Sleep is an essential activity of human being. However, there are lots of questions uncovered about sleep. First of all, why sleep is required is still uncertain.
My past entry: Five essences for beautiful sleep
My past entry: Stress reducing activities, 2 axis and 3 principles
Nathaniel Kleitman is known as a father of sleep research. He and Eugene Aserinsky, a student belonged to his laboratory, discovered Rapid Eye Movement (REM) in 1953 for the first time.
The New Yorker: Up all night
Several decades after, common sense of sleep has been changed partially.
For example, when I was a medical students, I was told that patients with insomnia should keep in the bed through night, even if he could not fall asleep, because rest awake in the bed helps him to regain his energy. However, this method is now denied as inappropriate. Continuing lying often strengthen the fear of insomnia of the patients, leading to inability of sleep. Instead, practitioners should advise them to get out of the bed when the patients feel not to sleep.
Regarding this topic, I recommend a book in which wide knowledge from the scientific evidence of the sleep to how to gain good sleep are described. I read it in 2003 in Japanese. It may not be out of date now. It is sorry that Kindle version is unavailable.
Amazon.com: The Promise of Sleep: A Pioneer in Sleep Medicine Explores the Vital Connection Between Health, Happiness, and a Good Night's Sleep
By the way, I have never experienced insomnia, fortunately. The only three exceptions were a night before an examination in college, after debating with my boss, and after long-lasting deep sleep with an illness.