Die kleine Schlafschule: Wege zum guten Schlaf

A pretty neat overview of all the different aspects of sleep and insomnia. Pretty much every chapter is only two pages long and condensed to the essential facts.

If you read other books about sleep you probably already knew most of this but it's a good little book for people who are new to the subject or want a little helping guide to know what they can do to improve their nightly sleep.