Internal Time

Chronotypes, Social Jet Lag, and Why You're So Tired

By: Till Roenneberg

Narrated by: Grover Gardner

Early birds and night owls are born, not made. Sleep patterns are the most obvious manifestation of the highly individualized biological clocks we inherit, but these clocks also regulate bodily functions from digestion to hormone levels to cognition. By understanding and respecting our internal time, we can live better.

©2012 DuMont Buchverlag, Cologne ( Germany) (P)2013 Gildan Media LLC

Critic reviews

" Internal Time is an accessible, up-to-date overview of a subject that is important to all of us. With its remarkable depth and breadth of coverage, this audiobook should be of interest to a wide and diverse audience." (Martin Zatz, Editor, Journal of Biological Rhythms)

A real pleasure!

This book kept me engaged from story to finish as it walks along the journey meandering between body clock and social clock. Both non-scientist and scientists will get something out of it. The reading is perfect in rhythm as in pronunciation. The illustrations are thoroughly explained and can easily be followed verbally and a pdf also accompanied the audio book.

Required Reading for Humans

This book provides an inclusive and scientifically supported exposition on sleep. Not only will you learn how sleep works on a theoretical level, you will also understand the practical consequences.

For example, Roenneberg explains that every person has a certain chronotype (from "early" to "late"). The biological clock of early chronotypes generates "internal days" shorter than 24 hours. This biological clock needs to be synchronised to the actual or "external" day/night cycle, resulting from the earth's rotation. This synchronisation happens (among other things) primarily through exposure to light. To synchronise a shorter "internal day", a person needs to be exposed to more light, which means waking earlier. The reverse is true for "late" chronotypes.

Your chronotype also dictates bodily functions (like appetite) and performance (like alertness or problem solving). A person with a late chronotype is therefore much more likely to perform worse in the morning than a person with an early chronotype. For such a person, morning can feel more like the middle of the night!

Furthermore, Roenneberg explains that your biological clock is in fact a biological phenomenon that cannot be altered by "simply showing some discipline". As he puts it: "early birds and night owls are born, not made".

Unfortunately, this is poorly understood in our "nine to five" society. A person with a late chronotype is often perceived as inferior. (This is even evident is our language, e.g. "the early bird gets the worm".) This person actually experiences "social" jet lag (possibly for his/her entire life). This social jet lag is similar to actual jet leg, in the sense that it is as if living in one time zone, while going to work in another. Needless to say, this has an enormous impact on a person's quality of life.

All of this and more is explained in clear language, but with scientific authority. I also found the book to be just the right length.

I believe this book contains knowledge every person should be aware of. At the very least people who struggle with sleep in any way should read this book. It will provide you with a great many insights.

Very educational, great facts, great narration!

I really loved listening to this audiobook, I listened to it on my commute to/from school, and always found myself intrigued and interested in what I was listening to. Narration was great as well as the writing. 10/10

well done if having a few trite anecdotes

Fascinating topic. The topic was both covered in depth but presented clearly enough for the general reader

great book about the working of the internal clock

absolutely loved it! the structure is great - a little story followed by some real scientific explanations (still understandable)

will tell everyone to read it