The Inner Clock: Living in Sync With Our Circadian Rhythms

by Lynne Peeples

How the groundbreaking science of circadian rhythms can help you sleep better, feel happier and improve your overall health

Your body contains a symphony of tiny timepieces, synchronised to the sun and subtle signals in your environment and behaviour. But modern insults like artificial light, contrived time zones and late-night meals can wreak havoc on your internal clocks.

Armed with advances in biology and technology, a circadian renaissance is reclaiming those lost rhythms. The Inner Clock explores the emerging science and its transformative How could taking a walk in the morning and going to bed at the same time each night keep your body in sync? Why are some doctors prescribing treatments at specific times of day? And how might a better understanding of our circadian rhythms improve educational outcomes, optimise sports performance, and support the longevity of our planet?

Science journalist Lynne Peeples seeks out the scientists, astronauts, athletes and patients at the forefront of a growing movement. Along the way, she sleeps in a Cold War-era bunker, chases the midnight sun, spits into test tubes, and wears high-tech light sensors to decipher what makes our internal clocks tick and how we can reset them for the better.

Genres: Nonfiction, Health, Science, Self Help, Psychology, Audiobook

354 pages, Kindle Edition

Published September 24, 2024

Reviews

[Jess Jackson · Rating 2 out of 5]

2.5⭐️ I picked this up hoping to understand how to optimise and be more in tune with my circadian rhythm to support my sleep cycle and overall sleep hygiene. I instead learnt a lot about the history of circadian rhythms and followed along as the author experimented with living in darkness for weeks. I picked up a few tips on how to support circadian rhythms but was really hoping for more action and advice on resetting and creating better sleep habits. Interesting but I think there are better books on sleep hygiene out there.

Also genuinely surprised by how well rated this book is! So maybe people are getting something out of this that I’ve missed.

[Elizabeth Weinberg · Rating 5 out of 5]

I happened to read The Inner Clock while profoundly jetlagged, and it was a revelation! Peeples provides a wealth of information about circadian rhythms. The Inner Clock is a lucid, engaging look at the impact the sun, light, and circadian rhythms have across our lives—from how we age and recover from illness, to how animals are responding to climate change. Peeples is an excellent storyteller and science communicator. I learned so much while reading, and was swept along by the narrative writing. Highly recommend, whether you're jet lagged or not.

[Sue Oshin · Rating 3 out of 5]

Based on Google seacrh, “Circadian”, comes from the Latin circa (around) and diem (day). Circadian refers to the circadian rhythm, which is the natural cycle of the human body that occurs every 24 hours. This rhythm controls physiological processes such as:

- Sleep and wake cycles
- Hormonal production
- Body temperature
- Metabolic processes

The Inner Clock by Lynne Peeples is suitable for individuals interested in exploring topics about time management, self-awareness and how the human "inner clock" affects productivity, health and life balance. It is also for those who is interested in understanding the scientific concepts behind circadian rhythms and how they affect emotions, focus, and energy. For individuals who want to learn how sleep patterns, meal times, and daily routines can support physical and mental health, this is the right choice!

The important/highlight contents in this book are:

•The importance of quality sleep, regular meal times, and adequate rest.

•Suggestions for organizing daily activities based on the body's peak productivity times.

•How to recognize individual energy patterns like morning person or night owl and capitalize on them.

•Tips for aligning your daily schedule with your circadian rhythm.

•Techniques for improving focus, energy, and mood throughout the day.

•Methods for dealing with distractions like shift work and time pressure.

[Randall Airst · Rating 5 out of 5]

Science journalist Lynne Peeples has produced a superbly researched, scientifically grounded, beautifully written book - with pragmatic tips on optimizing sleep. Ms. Peeples combines superb writing skills, a strong science background and tip-top story telling to keep the book firmly in readers' hands and the pages turning. I highly recommend Ms. Peeples' The Inner Clock as well as her articles! Randy A.

[Martha andrade · Rating 1 out of 5]

Un poquito de datos interesantes entre lo que parece la vida contada en historias de la autora… dios santo, escriba una biografía si tanto quería hablar de ella y sus historias

[Annahita · Rating 5 out of 5]

Thank you to Riverhead Books for the advance reader copy of The Inner Clock by Lynne Peeples; it is a fascinating exploration of the science behind our circadian rhythms and how they impact every aspect of our lives. I have said it before (and I’ll probably say it a million more times) – journalists (or writers with a journalism background) write the BEST nonfiction books. The Inner Clock is no exception; Peeples breaks down complex scientific concepts into engaging and accessible insights, making this book a must-read for anyone curious about how our internal clocks govern our sleep, mood, and overall well-being.

One of the best parts of the book is Peeple’s writing style – I felt like I was having a conversation with her in my living room, not reading a science-heavy nonfiction book. It is informative and inspiring, with a perfect blend of research, personal stories, funny anecdotes, and practical advice. It left me more aware of my body’s natural rhythms and motivated to make lifestyle changes for better health and happiness; I learned so much (even something as simple as if/when I take melatonin that I should take a few hours before bed/early in the evening and not right before I try and go to sleep like I’d been doing).

I have so much to say about what I learned, but I’ll end here — if you’re looking to understand yourself better and improve your daily routine, definitely pick this one up!

[Mazelit · Rating 5 out of 5]

What time do you go to bed?
If you're like most Americans, bedtime is contrite with insomnia of some sort. Inability to fall asleep — inability to stay asleep — paroxysms of naps instead of long sleeps.
This is a fascinating book that puts all this into perspective.
We see the effects the sun has on us, mentally and physically. We learn the science behind circadian rhythms. And, rejoice (perhaps...), the author argues that we can't change the way we’re physiologically made (morning person, night person, or an in-between dove).
Now, I personally disagree with this: after moving to Florida, my sleep-wake cycle did a complete 180. I went from falling asleep at 4-5am most nights to falling asleep at midnight. That basement closet with no windows in Virginia was probably awful for my sleep, and this book helps explain why.

This book is science heavy, but also narrative heavy. At times I felt like there was too much chit-chat, so I skipped some sections while reading so that I could focus on the science.

For instance: did you know that the blind still have normal 24 hour wake-sleep schedules despite not being able to see sunlight? Or that birth control impacts your body's ability to process caffeine?
The book also explores the emerging field of chrononutrition: the fact that what you eat and when (relative to the daylight hours) can have an impact on metabolism, mood and your sleep.

Great science book, but it would be better if the author condensed her storytelling a bit. 8.5/10. Very neuroscience heavy but not TOO dense. Peeples, the author, has an MA in science journalism, so she can translate the science into something easily understandable by an enthusiastic reader.

[Monica Macri · Rating 5 out of 5]

This was a great book! It was such an enjoyable read and I learned a lot of simple things I can do to adjust my lifestyle to sleep better.

[Dorothy DiMascio-Donohue · Rating 5 out of 5]

My #1 book to recommend and fact blurt to whoever I was with during reading. I love learning how to live in tandem with our body’s natural rhythms and turns out it doesn’t have to mean waking up at 5am with the sun bc I could nevvvvver!
Some tidbits:
- bright blue light during the morning and day is just as important as limited (red, if any) light during the evening for sleep
- my whoop already told me this but sometimes less sleep, at consistent times is better for you than more sleep erratically
- sunlight reigns supreme compared to indoor lighting: brighter, full spectrum, and comes at the right times of the day for our rhythms aka just get outside
- violet and red light is good for smooth transitions (dawn and dusk), melatonin production in the pm, cortisol suppression in the am
- eating or working out late at night can suppress melatonin production from beginning since your digestive system shuts down and night and your body needs to cool down to sleep

[Gail Sneed · Rating 2 out of 5]

I was looking for help in resetting to my natural circadian rhythm but there was very little on this topic. I came away with a few tips-wait 90-120 minutes after waking to have coffee, dim the lights in the evening, etc. Most of this book is about the history of circadian rhythm and how modern times have ruined them. A lot of descriptions of the author's experiments in an environment without sunlight or clicis

[Sona Kharel · Rating 4 out of 5]

3.5/5. It's one of the things that you know is very important for your health, but you don't end up abiding by the rules because of your own hectic work/life schedules. It's a good reminder-- didn't know that circadian rhythm could be THAT important for your health. Felt the book to be a bit repetitive tho; I was struggling to finish it by the end. Still a good read, very informative.

[Brianna · Rating 3 out of 5]

I am really interested in the topic of circadian rhythms and how our bodies/sleep schedules have evolved over time. While I don’t think I learned much that was new to me here, there were some good reminders. There are biological reasons why some of us are “night owls” vs “early birds”, and why some of us struggle to do things at certain hours. There was a lot about history and her experiment living in darkness, which was cool, but fewer practical takeaways.

[Mir Shahzad · Rating 4 out of 5]

Summary:

Your body operates on an internal clock, shaped by millions of years of evolution, that influences everything from your sleep patterns to your metabolism. Modern life, with its artificial light and irregular schedules, often disrupts these natural rhythms, leading to health issues ranging from poor sleep to chronic diseases. Your chronotype, or natural tendency to be a morning lark or night owl, is largely genetic, but can be influenced by environmental factors like light exposure. By understanding your chronotype and aligning your daily activities with your body’s natural rhythms, you can improve your sleep, boost your health, and enhance your overall well-being.

[Roberta · Rating 5 out of 5]

This is the best kind of popular science book: fun, enlightening, approachable, AND applicable to your everyday life. I’ve struggled with insomnia and came away with a lot of helpful tips. Everything in the book is backed by rigorous science but Peeples explains it with a light and humorous touch. Definitely will be recommending this to lots of family and friends!

[Jung · Rating 5 out of 5]

"The Inner Clock: Living in Sync with Our Circadian Rhythms" by Lynne Peeples delves into the profound connection between life on Earth and the invisible rhythms that govern it. Every living being, from the smallest algae to the largest mammals, operates on an internal biological clock tuned to nature’s cycles. Yet, the modern human lifestyle, dominated by artificial light and 24/7 schedules, has disrupted this harmony. The consequences are evident in poor sleep, health challenges, and a pervasive sense of disconnection. By understanding and syncing with our internal clocks, we can rediscover the natural rhythms that guide our bodies and minds, unlocking a path to better health and deeper well-being.

Circadian rhythms are universal, shaping behaviors like when sunflowers follow the sun or when birds sing at dawn. These cycles, driven by internal clocks, dictate much of life’s patterns across species. Humans, too, possess a master clock within the brain's suprachiasmatic nucleus, a minute structure that synchronizes the body’s functions. This master clock coordinates with peripheral clocks in organs like the liver and heart, maintaining a delicate balance that governs our sleep, alertness, mood, and metabolism. Ancient knowledge, such as Chinese medicine’s association of times with organs, reflects an early understanding of these rhythms, now confirmed by science.

When our circadian rhythms are disrupted, such as through jet lag or irregular schedules, the effects are profound. Listening to your body’s signals and understanding whether you’re an early bird or a night owl, a trait influenced by both genetics and environment, can help restore balance. Exposure to natural light is key; morning sunlight strengthens your internal clock, while dim evening environments help prepare the body for rest. Embracing these patterns not only promotes better sleep but also aligns you with the rhythm of life itself.

In the animal kingdom, adaptations to circadian rhythms are as diverse as the species. Dolphins sleep with half their brain active, ensuring survival in the ocean, while birds power-nap during flight. For humans, the concept of a chronotype explains natural tendencies toward being an early riser or a night owl. This predisposition is largely genetic, influenced by evolutionary factors like interbreeding with Neanderthals, who adapted to northern light cycles. However, behaviors and environments also play a role. Camping, for example, often resets our clocks by reintroducing us to the sun’s natural schedule.

By respecting your chronotype, you can enhance your productivity and health. Night owls should schedule demanding tasks for later hours, while early birds can make the most of morning energy. Consistency in sleep schedules and strategic exposure to light further reinforces these rhythms, allowing you to work with your body instead of against it. Our internal clocks, shaped by millions of years of evolution, function best when given the conditions they evolved for.

Modern technology, from electric lights to smartphones, has revolutionized human life but has also caused unprecedented disruptions to circadian rhythms. Historically, people lived closely aligned with the natural light-dark cycle, dictated by the sun. The invention of windows marked a step toward accessing more light, but even this innovation faced challenges like the 17th-century window tax in England, which led to fewer and smaller windows. In contrast, today’s world is saturated with artificial light, especially in the form of blue light from screens, which tricks the brain into staying alert long after sunset.

This relentless exposure interferes with the production of melatonin, the hormone responsible for inducing sleep. Over time, such disruptions can lead to severe health issues, including diabetes, mood disorders, and obesity. Yet, mitigating these effects is possible by creating environments that mimic natural light cycles. Warm, dim lighting in the evening and avoiding screens before bed can help restore your body’s rhythm. Making your bedroom a sanctuary of darkness with blackout curtains and prioritizing natural light exposure during the day are additional strategies to safeguard your internal clock.

The risks of circadian misalignment extend beyond poor sleep. Shift workers, who must override their natural rhythms, face heightened risks of chronic diseases like heart conditions and cancer due to the strain on their metabolic processes. Even minor disruptions, such as irregular weekend schedules, can have subtle but lasting impacts on immunity and mood. To combat these effects, consistency in sleep patterns and mindful eating habits—avoiding late-night meals—are essential. By maintaining a regular routine, you can protect your body’s finely tuned orchestra and allow it to perform optimally.

Historically, humans have relied on external cues to manage time. Before the Industrial Revolution, people lived in sync with daylight, and work schedules varied with the seasons. The advent of factories introduced rigid schedules, prompting inventive solutions like knocker-ups—people who woke workers by tapping on their windows. The eventual rise of mechanical alarm clocks cemented a more regimented lifestyle, pulling people further away from their natural rhythms.

Today, smartphones double as alarm clocks, often jolting us awake unnaturally. However, reclaiming a lifestyle where you wake up refreshed without alarms is achievable by syncing with your chronotype. Observing your natural sleep and wake times during periods free from obligations, such as vacations, can reveal your body’s true rhythm. Aligning your schedule with this pattern, while accommodating external constraints, can lead to more restorative sleep and improved health. Planning daily activities like exercise and meals around your energy peaks further optimizes this alignment.

Ultimately, "The Inner Clock" reveals that your body’s internal clock is a product of evolutionary refinement, finely attuned to the cycles of light and dark that have governed life for millennia. Modern lifestyles challenge these natural rhythms, but by understanding and respecting your chronotype, you can adapt without compromising health. Simple steps like strategic light exposure, consistent routines, and listening to your body can transform your relationship with time, helping you live in harmony with the rhythms of the Earth. This alignment not only improves sleep and productivity but fosters a profound connection to the natural world.

[Sarah Cupitt · Rating 3 out of 5]

Felt needed since my sleep is just chronically awful. Already do what the book says albeit in summer i could get more sun in the morning if i want to burn like a crisp for a few mins to help reset my body clock a tad to adapt to daylight saving time

Quiz results for chronotype separate to this book but relevant for notes:
- dolphin (hasn't changed from last time)
- sleep score of around 60 (lower than what fitbit tells me)
- About 10% of people have the dolphin chronotype, which is the hardest to form a schedule around without sacrificing sleep quality. This chronotype gets its name because dolphins in the wild remain alert while sleeping to evade predators. People with this chronotype tend to be sensitive to light and noise while they sleep, and prone to fragmented sleep patterns. Many are considered insomniacs. However, dolphins have a strong productivity window between 10 a.m. and 2 p.m.

Notes:
- Deep in your brain, in a tiny region called the suprachiasmatic nucleus, sits your master clock. This cluster of cells, no bigger than a grain of rice, sets the tempo for your entire body.
- Your master clock doesn’t work alone, either. It sends signals to mini-clocks in your organs, like your liver, heart, and muscles.
- Notice when you naturally feel most alert, and when you start to wind down. This can help you identify your chronotype – whether you’re an early bird, a night owl, or somewhere in between.
- sleep patterns are as diverse as the creatures themselves. Take dolphins, for instance. These marine marvels sleep with half their brain awake, allowing them to surface for air and stay alert for predators. On land, birds can catch quick power naps during flight, while some desert animals are nocturnal to escape the scorching heat.
- Your sleep-wake cycle, or chronotype, is a complex trait shaped by both nature and nurture.
- If you’re a night owl, don’t force yourself into an early-bird schedule unless absolutely necessary. Instead, try to align your most important tasks with your peak alertness times. (already do)
- Second, pay attention to your light exposure. Get plenty of natural daylight, especially in the morning. This helps set your internal clock. In the evening, dim the lights and limit screen time to prepare your body for sleep. (already do)
- window tax?
- Your body's internal clock relies on natural light cues to regulate sleep-wake cycles. But in our world, you're bombarded with artificial light long after the sun goes down. Your smartphone, TV, and even your energy-efficient LED bulbs are emitting blue light that tricks your brain into thinking it's still daytime.
- Consider shift work. Humans aren’t nocturnal creatures, but modern life demands that some of us work into or even right through the night. If you’re a shift worker, you’re essentially asking your body to function at its lowest ebb, when it’s programmed to rest and repair. This constant disruption of your natural rhythms isn’t just about feeling tired – it can lead to a host of health problems.
- Studies have shown that shift workers face higher risks of heart disease, diabetes, and certain types of cancer. Your body’s metabolic processes, which regulate things like blood sugar and cholesterol, rely on consistent circadian rhythms.
- On your next vacation or extended time off, allow yourself to sleep and wake naturally, without alarms. Note the times you naturally fall asleep and wake up. After a few days, you'll start to see a pattern emerge – this is your natural sleep-wake cycle.

[Kathy Richardson · Rating 5 out of 5]

Another book everyone should read. (see also Why We Sleep and Outlive) There's so much to know about the Circadian Rhythm and how it affects just about every aspect of our well being.
The author delves into some areas that likely need alot more research but I appreciate her giving an overview of current knowledge on the topic.
I feel vindicated and validated by the finding that teenagers need more sleep and to sleep later. High school starting at 7:25 a.m. nearly did me in. To wit: Florida has now passed a law that high school can not begin before 8:30 a.m.!

[Catherine Klein · Rating 5 out of 5]

Fascinating stuff. This book validated my sensitivity to and/or HATRED of blue light, bright/florescent lighting, daylight savings time, red eye flights, alarm clocks, alcohol, caffeine, and capitalism. 


I will no longer fight my biological clock and judge myself for "sleeping in" every morning. 


Also, animal rights activists should be talking about light pollution!!

[Emma · Rating 4 out of 5]

Reading this book as we set the clocks back last Sunday couldn’t have been more perfect. In “The Inner Clock,” Lynne Peeples dives into the science of circadian rhythms, and why exactly, we’re all so tired.

Written in a narrative nonfiction style, readers are privy to Peeples’ personal experiments tracking her own circadian rhythms. The book is supported with explanation of various studies and a history of circadian rhythm science.

I found the science here fascinating. I couldn’t stop telling people about it and asking if they think we should end Daylight Savings (and if that means we should stick to Standard Time of a permanent Daylight Savings). I did find the narrative a little less interesting though, even though this is usually the highlight of narrative nonfiction. In addition, the constant reiteration of the fact that studies are not exactly clear and that the data only points towards many of the concepts mentioned also made the book feel a little less credible than I would have liked.

Overall, I’m glad I read this. There are a few tips for better sleep I’ll take away, though that is not the focus of the book. As someone already interested in sleep science, this appealed to me, and if you share that interest, I’d say check it out!

Thank you Riverhead Books for the gifted copy.

[Tabitha Kronenwetter · Rating 5 out of 5]

Outstanding. This book legitimately changed my life. Applying just a few of the things I learned from this has radically improved my sleep and my energy. I can't recommend this book enough. Everyone everywhere should read it.

[Joe Sikma · Rating 4 out of 5]

Good read. More info than “don’t stare at your phone before bed and don’t drink caffeine after noon”… but maybe too much more info. The number of studies and anecdotes referenced made me… sleepy. The content could be pared down without losing the core themes and messages. It was informative and persuasive nonetheless! Skim if you have to but don’t skip.

[Darcia Helle · Rating 4 out of 5]

Does anybody really know what time it is?

My circadian rhythm is always out of sync with the clocks. I’m a night owl who grew up with an extreme morning person mother, raised two children in a morning world, am married to a morning person, and my oldest dog literally gets up with the sun, despite the blackout curtains. It’s a conspiracy against me!

THE INNER CLOCK is a fascinating book that puts all this into perspective. We see the effects the cycles of the sun have on us, physically and psychologically. We learn the science behind circadian rhythms. And, rejoice, the author confirms that we cannot, no matter what the world tells us, change the way we’re physiologically made (morning person, night person, or an in-between dove.)

This book is, by necessity, science heavy. But the author does an excellent job of breaking down all that science, making this an easy and interesting read.

For instance, have you ever thought about the way high-rise buildings in cities drape parks and yards in constant shadow, creating a lack of sunlight. And did you know that LED bulbs are bad for circadian rhythm because they contain too much blue light?

If you’re someone who always feels slightly out of sync with the world, if you have trouble sleeping, or if you’re just curious and love to learn, this is a book for you!

*I received a free copy from Riverhead Books.*

[Dan Meyer]

For anyone who has ever stared at the ceiling at 3am wondering why they're still awake, or pondered what makes someone a morning person or a night owl, or considered adjusting their routine to foster better sleep, this book is a must-read. Peeples' writing is engaging and her enthusiasm for the subject is infectious. You'll learn all about the rapidly expanding world of circadian science and explore all of the ways that our genetic makeup, environment, diet, and light-exposure affect the delicate rhythm of our bodies' clocks. I was particularly fascinated by her discussion of the science surrounding light sources and our exposure to natural light and I'll definitely be making some lifestyle changes in those areas. It's easy to imagine circadian science being a dull subject, but Peeples' manages to make it a delightful journey. I can't recommend this book enough.

[Kara · Rating 4 out of 5]

Honestly, this was fascinating even if I was expecting more of a self help book. This book was a scientific study of our circadian rhythms and how and why they happen. The author explores related topics, such as how that rhythm affects medical efficacy depending on the time of day you receive it, how some people really are "night owls" due to their own biology, and how we all have slightly different circadian rhythms, so things like alarm clocks and schedules dictated by society are detrimental to our body's individual rhythm.

I will say I went into this expecting more of a self help book with tips on sleeping better, so once again, the marketing is off, a recent trend I've noticed in publishing.

[Dana · Rating 5 out of 5]

This book helped me understand that circadian rhythm is multiple (rhythms) and that is so much more than what time you go to bed. There are so many factors that create good circadian rhythms. I enjoyed the different experiments the author did herself to help her understand this area of science.

[Nell · Rating 3 out of 5]

All my life I’ve skewed later than the clock on which society runs and thought myself in the minority. Not so: society runs on lark time, but there are actually more owls and doves (the in-betweens) than larks. Nonetheless, modern life puts us all out of sync with circadian rhythms to some degree. Although science hasn’t yet discovered the mechanism that makes body clocks run, we do know that besides the brain’s master clock, there are peripheral clocks for organs, tissues, and cells that respond to other cues. Living things from bacteria and molds to insects and plants have internal clocks, as well as animals. Body clocks affect wake and sleep times, the release of hormones and other substances in the body, and hunger, among other things.

Factors that put us out of sync with our body clocks:
• Insufficient exposure to natural light and excessive exposure to artificial light
• The length of light waves emitted by incandescents vs. LEDs (red vs. blue)
• Amount and timing of looking at screens
• Not only what you eat, but when you eat
• Shift work
• Timing of work and school hours
• Travel
• Pollution and industrial contaminants
• Chemicals in personal care products and pharmaceuticals

Not only does the disruption of our circadian rhythms affect our sleep, it can also contribute to metabolic disorders, like obesity and diabetes, and other diseases. Timing of events such as away games for sports teams may confer advantage or disadvantage because of travel. Twice a year when the time changes, we experience an increase in accidents and sick days and a decrease in alertness, performance, mood, and sleep quality. Our food supply depends on pollinators and plants, which can have their circadian rhythms disrupted.

Some measures have been proven to help, such as getting daylight outside, especially in the morning. Others have not been widely adopted or are still being researched, such as using light only as much and where needed, both to help prevent disruption of sleep and to boost performance; starting high school later and elementary school earlier, to follow kids’ natural wake and sleep times; adjusting work schedules to individual preference, which can increase productivity along with making employees happier; using building design, tunable LEDs, and skylights to mimic the kind of light we need; timing the administration of vaccines and other drugs or undergoing surgery to increase the benefits and reduce side effects.

The book contains much more detail, for those who want to take a deep dive. Besides her research, the author wore monitors, slept in underground bunkers to avoid light, and timed her eating, among other things. Depending on your level of commitment, the book contains some ideas for ways to help get your circadian rhythms back in in sync.

[Patrick E · Rating 5 out of 5]

This year I have gone out of my way to read books that blow my mind. Richard Powers and "Playground." "Carbon: The Book of Life" from Paul Hawken. Robert Macfarlane, "Is The River Alive?" While my advocacy work discussing and working to mitigate light pollution meant I was not a complete newbie to the subject of our circadian rhythm, my brain was still firing so fast after recently finishing “The Inner Clock: Living in Sync With Our Circadian Rhythms” by Lynne Peeples that I (ironically) had a little trouble falling asleep. A science journalist whose work I have read before in The Guardian and Scientific American, Ms. Peeples takes us through the latest science and understanding of the inner mechanics and gears of the system that governs much of our health and or lives — the circadian clock.

That work in the light pollution space has caused me to become increasingingly drawn into the broader circadian world. Over the last couple of hundred years we have shifted dramatically away from the habits that our bodies evolved with — instead of being active during the hours of daylight, and sleeping/resting during darkness, we have turned towards a 24/7 lifestyle. We have, with electric lighting, banished the cues that our bodies depended on to manage the biological systems that we rely on.

Combining firsthand research, interviews and an accessible writing style, this book gives a reader everything they need to address one’s own circadian problems, and tools to get back into some semblance of a normal routine. Routines that will help you live healthier and happier. Highly recommend to anyone remotely interested in the need to protect the night. And for anyone that struggles to get moving during the workday as I do.

#TheInnerClock #circadianrhythm #circadianclock #protectthenight #lightpollution #sleepmatters #getsomerest #readabook #reading #books #lynnepeeples

[Sekar Writes · Rating 4 out of 5]

Full review and summary.

I knew that our body’s natural rhythms, or circadian clocks, affect our daily lives, but until I read this book, I didn’t realize the full significance, history, and overall impact of circadian rhythms. It opened my eyes to how much we take these rhythms for granted, even though they are constantly at work behind the scenes.

Peeples blends her personal curiosity about circadian rhythms with solid science. It’s not just a biology book (which is what I expected at first)—it also touches on history, like how daylight saving time first applied, and how modern life makes it harder to stay in sync with our body clocks. It’s an interesting read, but a heads-up—there’s a lot of scientific detail. If you're like me and enjoy learning the “why” behind things, you’ll appreciate it. But if you’re looking for simple sleep hacks, some parts might feel a bit overwhelming.

How to find your “optimal sleep window”—the best times for your body to go to bed and wake up—is a great advice, but I’ll admit, it’s hard to apply in a busy lifestyle. The book offers practical tips, but not all of them are easy to follow in everyday life.

[Matt · Rating 2 out of 5]

A cursory overview of circadian rhythm information. Down to two stars because in general the author spends a lot of time on a huge volume of circumstantial or speculative research without adequate contextualization of the findings.

Even in areas that are fairly well researched she does a rather poor job of contextualizing information. The volume of words spent on various blue-light blocking technologies and strategies is probably 10x the number of words (though it is mentioned, briefly, a few times) spent emphasizing that the *absolute quantity of light* is far more important than the particular light spectrum one is exposed to.

The book also spends quite a lot of its attention on the COVID pandemic and, I think, will hold up remarkably poorly as the references to it become dated and further from our collective memories. Using once-in-a-lifetime events to evidence things that occur on a daily basis is sometimes an amazing research opportunity and sometimes a sensationalistic way of reporting things that are irrelevant to our modern lives.

All in all a disappointing book. Save yourself the time of this one and read Till Roenneberg's (who Peeples quotes at length) amazing "Internal Time" if you want to learn about chronobiology.

[Ali · Rating 3 out of 5]

I read this book when jet lagged, and now coming to review it, my memories of the details are a little hazy. I'd call this ironic but that isn't what ironic means. Grimace worthy, yes.
What I do remember is that a) there was a wealth of detail on how to better align your circadian rhythms, b) it was a little terrifying to realise the impact of indoor life and our unhelpful approach to lighting* is, c) Americans still start schools at ludicrous hours of the morning and should just stop and we shouldn't need evidence on anything for that, it is just dumb d) Peeples, like many experts deeply engaged with their subject, can see cicardian disruption at the heart of most social ills - at times perhaps in isolation from other things. e) At times, Peeples seems to want to return to some kind of idealised relationship with our natural clocks - and one based on static hours, rather than changes with the seasons. Humans, however, did not really evolve on the equator - I thought this was odd.
Would recommend, but maybe try reading it when appropriately rested.

*Nowhere near bright enough during the day; far too bright and far too blue at night.