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

3.73 of 5 stars 3.73  ·  rating details  ·  307 ratings  ·  51 reviews
Early birds and night owls are born, not made. Sleep patterns may be 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. Living at odds with our internal timepieces, Till Roenneberg shows, can make us chronically sleep deprived and more likel ...more
Hardcover, 288 pages
Published April 2012 by Harvard University Press (first published February 18th 2010)
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Community Reviews

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The question "Why I am I so tired" was a major one for me at the time of reading this book. It's not a self help book but just reading his research on sleep really helped me put my own situation in perspective. As a late chronotype myself, I particularly enjoyed how he defended us, by demonstrating that the old adage "the early bird gets the worm" might well have applied to a traditional agrarian community but it is not necessarily true for modern city dwellers.

My rating is based on the comprehe
Lois Bujold
Jun 07, 2013 Lois Bujold rated it 4 of 5 stars
Recommends it for: Night owls, and the Larks who live with them.
I could hardly write a better review than this one, which sent me to Amazon Kindle to buy a copy:

24 chapters of the latest news from sleep studies. Good and useful information for Owls like me, and the Larks who have to live/deal with them.

The one item I was hoping for, and did not find in the read, was anything on studies of sleep disruption in women enduring menopause. It seems to me this would be a perfect natural laboratory to study endogenous sleep re
Are you a lark, or an owl? Do you bound out of bed 15 minutes before your alarm sounds, or are you continually hitting the snooze button ‘just one last time’? The culprit is your internal clock, a biological device found even in creatures as lowly as bread mould, which is used to synchronise our waking activities to the sun.

Roenneberg argues that your ‘chronotype’* – whether you are an early bird or a night owl – can impact several things in your daily life. Covered are topics like why teenagers
Great article on the book:


By the way, this is another "heavy on the details" style review. If you just want the thumbs up/ thumbs down on content, writing style, and scientific accessibility, scroll to the end of the review.


This is the book for all you night owls that are always fighting the "early to bed, early to rise" philosophy.

1) "Early to bed, early to rise" is a remnant of agrarian society when you needed to get outside work done while t
Many of the negative reviews of this book are from people who were expecting self-help literature for sleeping disorders, or who get bored easily when things get sciencey. That being said, some of the "stories" are a bit cringeworthy, but I'm willing to forgive the author for that. Overall, I enjoyed this book quite a lot, but my opinions are biased because I'm a) extremely interested in circadian cycles, and b) a late chronotype. I wouldn't necessarily recommend that everyone read this book, bu ...more
Stefan Kanev
This is a very interesting book about sleep.

It's not a self-help book. There are no advices on how to approach sleep, nor recipes to improve it. It just tells a lot of interesting things about how we sleep, how our body keep track of time and what happens when it looses synchrony with the external world. The book is written in a nice style, where each of the 24 chapters starts with a fictional story illustrating a point about the ideas ahead, then followed by a detailed discussion. It's pleasant
The subject was interesting, and there was some good information here, but the book as a whole I didn't enjoy. The anecdotes to start each chapter ranged from average to excruciating, and did little to move the book forward.

Glad to be done with this.
Upside: This book confirmed my hatred of mornings is genetic and therefore really not my fault. Downside: I will peel myself off the mattress until I die.
Fiona Leonard
There are some books that immerse you in a topic and you come away feeling wiser and inspired. Then there are other books that lead you to the edge of learning, throw you a few tasty morsels and then turn off the lights and send you away. For me, Internal Time: Chronotypes, Social Jet Lag and Why You're So Tired, sits squarely in the latter category.

This is a book about the science of sleep. According to the science, sleep is not something that is governed entirely by choice. Instead, it is some
A scholarly discussion of the study of the human body's internal clock, and the significant aspects of the field of sleep research. Although Roenneberg clearly strives to make his points accessible by including an illustrative story (in conversational tone) at the onset of each chapter, the concepts can get a bit heady. He divides the book into 12 chapters of two parts each, to mimic the night/day rhythms of our lives and our planet, and fitting as this is to the theme of the book, it seals it a ...more
Steve Bradshaw
Fascinating content but awfully written.

Simple concepts are explained in such convoluted complex ways that I had to reread a few sections to make sure I hadn't missed the point. The author has no ability to simplify the research into a clear narrative. The fictional chapter intros made me throw up a little in my mouth each time.

I gave it one star since zero doesn't seem to be an option. Malcolm Gladwell, please will you help rewrite this book!
I *wanted* to like this book, but I felt I got more out the NY Times (I think) article where I heard about this book in the first place. I can't help but wish that Mary Roach had written about sleep...because at least I wouldn't have felt like sleeping while reading this book. Ha...ha? Get it? Anyway. Didn't love it; felt it was too heavy on statistics and boring explanations. Shame.
Barb Wilson
This is a book about the science behind sleep recommendations that we've probably all heard before. The beginning was interesting but then my brain could not stay focused on the last few chapters which I skimmed. I would have preferred a book aimed at helping a person identify what chronotype they are and how to manage that. Other than: get more sunlight during the day.
I was a little disappointed with this book in that it had such potential. I would have liked more suggestions on how to properly use this knowledge of our body clocks.

Interesting none the less on why we sleep the way we do.
Jessica Davis (Eckert)
Fascinating book about the science of sleep and the human internal clock. The author has studied this subject his entire life and was the protege of the guy who studied it for HIS entire life before he passed the torch. The author has an enormous database of sleep research and testing. But he uses stories to educate his readers about the topic and make the data meaningful.
Topics covered include how light, electronics, exercise and food impact sleep cycles, and how these influences are changing u
Sep 08, 2014 Wendy rated it 2 of 5 stars
Shelves: 2014
I applaud the author's attempt to make the book more interesting with case studies, but the case studies just aren't that interesting. I would have rather read the book without them.
Catherine Gillespie
Roenneberg presents a fairly readable account of the science behind sleep. It turns out that people are born with genetic chronotypes making them tend toward being early birds or late owls. The social story is that people who sleep late are lazy (“the early bird catches the worm!” type sayings are common in most languages) but actually they just respond differently to time and light on a cellular level. Roenneberg describes some fascinating studies on how this works.

{Read my full review here}
I just wish this book had a last page of "sleeping best practices." Lots of good information here.
Oleg Kagan
I first read about this book in the Brain Pickings newsletter and I'm glad I looked it up. Till Roenneberg has written a readable introduction to the state-of-the-art in sleep research which answers all the pertinent questions people have about why we sleep when we do. This isn't a how-to guide, but a run-down of experiments on various aspects of our internal (and as it happens, external) time.

Breaking each chapter down into a story followed by an explanation makes the science easy to grasp for
Fiona Cox
Disappointing. It didn't know whether it was a textbook (second halves of the chapters would have been ok as an introductory textbook) or pop-sci (those increasingly irritating stories at the start of each chapter). Ended up nowhere and failing to answer many of its own questions.

I listened to the audiobook and admit it may have been better as a paper read than a listen.
Christine Martin
So, I'm taking away the fact that I am an extreme late type, and I am no longer going to feel guilty about being cranky when I have to be out in public, like say a meeting, before 10:00 AM. Lots of information, not sure I processed all of it, but I am feeling better for having read/listened to it. I'm glad this info is out there.
Lots and lots of interesting information and scientific studies on the body clock and sleep. Basic takeaway is that you can't change your chronotype (if you are a lark, or a night owl, you are stuck). It's not easy to read on Kindle as there are lots of charts to accompany the studies, and I don't think they are labelled well enough. I got a bit frustrated as I was hoping he would make more of an effort to tell me what was really important and what wasn't. So I wouldn't say it's as mass-market f ...more
Topboek! Wat ik vooral interessant vond, was het hoofdstuk over het verplaatsen van mensen naar een andere planeet. Verfrissend om te lezen hoe de kennis die we nu hebben over de biologische klok in een heel andere context geplaatst wordt.

Ik las dit boek voor mijn profielwerkstuk, dat ik schrijf over de biologische klok. Nu had ik al recensies gelezen waarin mensen klaagden dat het zo langdradig was, dus ik kneep hem wel een beetje. Achteraf kan ik zeggen dat ik het niet langdradig vond, ik von
I found this book to be interesting, and I liked how it was organized; the fictional anecdotes at the beginning of each chapter made the "sciencey" parts easier to understand. I am left wishing there were more takeaways from this book. There's a lot of information with very few practical tips or suggestions. As a later chronotype living in an early world, it's kind of a bummer that there seems to be little I can do about it.
Oct 10, 2013 Sun rated it 4 of 5 stars
Shelves: 2012
There are 24 cases and chapters in this book exploring the world of chronobiology and circadian rhythms. In problem-based learning format, Roenneberg produces very readable prose and isn't afraid to include charts. There are some wonderful turns of phrase and dry humour especially in Chapter 2 which debunks the myth of late sleeprs as lazy and reframes it in terms of a cultural preference for early risers. Chapter 13 discusses changing policies around cultural timing preferences and frustration. ...more
Danielle Dinh
I had too much expectations for this book and it only fulfilled half. The middle chapters were slightly confusing and boring. The vignettes at the beginning of the chapters were rather ordinary. Mr. Roenneberg kept referring to the discos. I think he meant to call it clubs. Unless that is what they are called in Europe. All in all, I enjoyed learning about social jet lag. Society would function more efficiently if more people took chronobiology into account.
Mar 06, 2015 Emily added it
Fascinating information about our body clocks. Great information for parents of adolescents, too. Need to reset your body clocks? Spend the day outside in natural light -- away from urban areas.
Makes you understand your body clock and make you less judgemental about those who have different body clocks than you.
Eduardo Zárate
Intelligent pop sci book on one of the less known fields of life sciences - chronobiology. Social experiments and biological discoveries are cleverly intertwined to build a strong case against the arbitrary nature of our work/sleep schedules - and its potential health consequences. Despite some excessively didactic chapter intros, a very entertaining read.
Well written. Understand that topics like this can come off as dry and way too scientific for the non-scientist but author uses great analogies and applies everyday situations to help readers understand concepts. He leaves the more scientific details for the footnotes. Although I would have liked more details. Otherwise very interesting topic.
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Till Roenneberg is a professor of chronobiology at the Institute of Medical Psychology at Ludwig-Maximilians University (LMU) in Munich, Germany. Roenneberg, in collaboration with Martha Merrow, explores the impact of light on human circadian rhythms, focusing on aspects such as chronotypes and social jet lag in relation to health benefits.
More about Till Roenneberg...
The Neurobiology of Circadian Timing

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“The phase of an individual’s body clock in relationship to a zeitgeber is a biological phenomenon and not a matter of discipline.” 1 likes
“when two strains compete for the same resources, the strain with an internal timing system that is most adapted to its temporal environment has the greatest advantage.” 0 likes
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