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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

3.68  ·  Rating details ·  681 ratings  ·  88 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 ...more
Hardcover, 288 pages
Published April 2012 by Harvard University Press (first published February 18th 2010)
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Average rating 3.68  · 
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Lois Bujold
Jun 07, 2013 rated it really liked it
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
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
Nov 06, 2012 rated it really liked it
Shelves: non-fiction, _kindle
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
I became familiar with Roenneberg's work while taking a chronobiology course that mentioned him and the subject matter in this book. The writing style is a bit like a textbook. I listened to an audio version of this book and found myself zoning out. About a 1/4 through the book, I had to start over and make myself pay attention. Once I did, I loved this book.

While taking chronobiology, I learned about the various chronotypes in humans and how this would affect travel to Mars. I had never
Jul 19, 2012 rated it really liked it
Shelves: physical-copy
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 sleep
Apr 20, 2017 rated it really liked it
Fascinating new information such as that some people make their melatonin in the day time and so should sleep in the day time which is NOT accepted by our society overall. Larks think everyone should be larks. Owls are more extroverted which sure surprised me. They are also more innovative.

Children born with Smith-Magenis syndrome are very crabby from being expected to be awake during the day when they are producing melatonin. They can be helped by a beta-blocker in the morning and
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, ...more
Mar 15, 2013 rated it really liked it
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.
This was an accessible book for the non-scientist. A well-written description of internal time, that internal sense we all have that controls the rhythm of our daily lives. Where does it come from? How does it manifest? Can it be affected by other rhythms, environmental, social, or artificial? The author is an experienced chrono-researcher and was able to clearly describe a lot of the recent research that has illuminated our understanding of chronotypes and the workings of internal time.
Jun 27, 2013 rated it it was ok
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.
Bianca (theperksofbeingbianca)
I've wanted to read this book for a while, and I finally did.

The title in itself caught my eye: I wanted to know more about chronotypes, specially more about why I am a night owl and how can I use that to my advantage in life. The thing is that I'm not so sure that I am an owl anymore. The time when I considered myself one was back in 2012 or so, when I was a teenager and was still in school. I usually went to bed late and I pulled many all-nighters during exam season. I even pulled some out of
Jan 15, 2019 rated it liked it
Interesting and thoughtful, but ultimately disappointing and not particularly recommendable. There are 24 chapters, and each one has a case study about a different aspect of our internal time clocks, and then a detailed discussion about that aspect and the scientific evidence to date about it. The presentation is somewhat unique in that way, and the author clearly had fun writing this. (Its also very clear that hes Europeanthat tone and style comes through, even in the translation.)

What was
Aug 20, 2019 rated it liked it
Although filled with interesting lessons about the body 'clock,' the writing was a burden (the idea of fictional intro stories is a good one though). Some lessons that made it worthwhile:
More exposure to light (outdoor work vs indoor offices) means stronger 'zeitgeber' for country-folk (thus their earlier waking due to 'compression' of sleep cycle).
Role of stress of social jet lag leading to smoking in teen years [I note a large share of smokers in Central Europe - perhaps related to being in a
Feb 09, 2017 marked it as did-not-finish
Not what I was looking for. Gave up early.
Fiona Leonard
Sep 20, 2013 rated it liked it
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
Stefan Kanev
Jan 14, 2015 rated it really liked it
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
Jan 05, 2013 rated it liked it
Shelves: adult-nonfiction
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 ...more
Steve Bradshaw
Nov 04, 2013 rated it did not like it
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!
Barb Wilson
Feb 24, 2014 rated it it was ok
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.
Jun 17, 2012 rated it it was ok
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.
May 15, 2012 rated it liked it
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.
Mar 08, 2014 rated it it was ok
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.
Nicole Harkin
Sep 11, 2012 rated it really liked it
I just wish this book had a last page of "sleeping best practices." Lots of good information here.
Clark Hays
Aug 29, 2017 rated it really liked it
Social jet lag is a thing (and I definitely have it)

This is an interesting work by an esteemed researcher on the science of sleep. Using simple little stories, he profiles 24 (irony intended) insights into our internal clocks, how they are aligned to external factors (like the daily cycles of light and dark) and what it means for us as individuals and as a society when they are out of synch.

And they are always out of synch.

Turns out our chronotypes are predetermined by genetics and a handful of
I enjoy learning about subjects I'm not -and probably never will be- an expert of. When I heard about this book, it seemed only logical that I would give it a try; after all, the question "Why am I always so tired" has surely passed all of our heads a few times in our lifetime.
I've been planning to read it for a long while now, but always had something else to read, so my anticipation grew larger and larger without realizing. So I started it with big hopes, but around halfway in, I started to
Stephen Simpson
Jul 01, 2019 rated it it was ok
Disappointed and underwhelmed.

I was eager to read this, as I find circadian rhythm, biological clocks and so on to be fascinating. Unfortunately, the book included far too many anecdotes that were "okay" at best and "excruciating" at worst. I understand the author was going for a mass audience, but I think he ended up dumbing down the book without any real value-add. With that, I found the actual science content to be more than a little lacking.

I also found the more editorial moments to be
Scott Wozniak
Jan 31, 2018 rated it really liked it
This was extremely well written book on a technical subject. I wish I could give it five stars. But I can only go 4 out of 5. Partly, that's because it's truly technical (though he did a great job explaining the details, it was still very detailed).

Partly, that's because he did a masterful job explaining how our body clocks work--but offered little to no advice on what to do about it. For example, he explain jet lag and how different types respond to different kids of time zone changes. But he
Jan 21, 2017 rated it liked it
As a night owl who always thought I could accomplish more as a morning person, this book was of particular interest. We do have internal clocks that are rather rigid. There was lots of good information.
* The siesta culture shows that there is some flexibility in how and when we attend to our individual sleep needs.
* The maximum number of suicides worldwide occurs around the summer solstice.
* People have difficulty taking seriously the body clock and its biological impact on our lives.
* Among the
Jul 22, 2019 rated it it was amazing
Recommended to Maurya by: Gretchen
Shelves: growth, o-cin
I personally loved this book. As a very early bird (an extreme Lark, I now know) it was great to have the different body clocks explained, along with the studies done, and the vignettes that accompanied each of the 24 chapters.

I now understand why my husband and I do not (pretty much ever) go to bed at the same time. Our body clocks are almost opposites! I have a better appreciation for how he operates. It's also interesting to see what the kids do and are doing.

I totally recommend this one, if
Oct 14, 2019 rated it really liked it
Came upon this book after reading Daniel Pink's book 'When' and wanted to delve more into the science behind the different types of chronotypes. Definitely an interesting read into the the science of our internal clocks and how biological, cultural, geographical, professional, and environmental aspects affects one's body clock. While it touched slightly on how one can find ways to be more in alignment with their internal clock, I would have loved some more recommendations. Definitely a topic ...more
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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.

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