Pourquoi rêvons-nous? Pourquoi dormons-nous? - Michel Jouvet

This slim (only 120 pages long!) book answers all the basic questions of sleep, the Where? When? and How? of all the kinds of sleep that exist (deep sleep! Rapid Eye Movement sleep - or "sommeil paradoxal", as they say in French!) and related phenomena (circadian cycles!). It also points out some interesting hypotheses about the Why? of sleep - but, as it states repeatedly, nothing's proven yet.
Honestly, it was an interesting book about the physiology of sleep (physiology! neuroscience!), and it was a very accessible read; it follows a kind of question-and-answer format, where the questions were asked by a teenager and the answers were tailored in accordance.
Also, it's pretty obvious that it was written by a physiologist: there's numerous references to physiology as "the queen of all sciences", and the author doesn't shy away from being highly skeptical about the importance of genetic research. Intra-biological sciences rivalries: love it!
Yay, sleep!
Oh, and for those who care about such things: the Dewey numbah is 612, so it's a book about Technology, more specifically the Medical Sciences, or to be even more precise, about Human physiology. Yay, physiology!