Life Time: Your Body Clock and Its Essential Roles in Good Health and Sleep

by Russell Foster

A fascinating journey through our circadian rhythms, sleep, and health, by a world-leading expert on circadian neuroscience
 
“Full of surprising and useful facts. . . . Unlike many science books with similar subtitles, it really might ‘revolutionise’ your life.”—James McConnachie, The Times (London)
 
“Life Time should certainly be mandatory reading for night-shift workers, but its messages are so universal that it would be hard not to gain some sleep smarts from its pages, whoever you are.”—Alex Wilkins, New Scientist
 
The routines of our modern lives—home working, night shifts, technology—are playing havoc with our body clocks, sleep patterns, and health. Packed with cutting edge science, this book by award-winning scientist Russell Foster takes the reader on a journey through our days and nights, and explains how we can get back into rhythm and live healthier, sharper lives.
 
In the past few decades, there has been an explosion of discoveries around the science of the body clock and our twenty-four-hour biological cycles. Sleep and daily rhythms emerge from our genetics, physiology, behavior, and the environment. Like most of our behaviors, they are not fixed. These rhythms are modified by our actions, how we interact with the environment, and how we progress from birth to old age.
 
Cutting through long-standing myths, Foster empowers readers by providing concrete information and guidance that can be used to understand what makes the body clock “tick.”

Genres: Nonfiction, Health, Science, Self Help, Psychology, Biology, Mental Health

482 pages, Kindle Edition

Published August 30, 2022

Reviews

[Ted Richards · Rating 4 out of 5]

I picked this up thinking it would be a nice, easy self-help book about getting better sleep. It was, in fact, a hard science deep dive into the mechanics of circadian rhythms, light patterns and human biology.

Russell Foster opens the book with some simple ground rules. Everyone is different. There is no 'one way' that a person's body clock should work. Some people are 'larks', and have an early chrono type, some people are 'owls', and have a later chrono type. What is so satisfying about Foster's early chapters are that they do not attempt to universalise the phenomena he is discussing, and he treats each subject with a great deal of care when he is going through it. He frames every study he puts forward as one subject to numerous repetitions an highlights areas in circadian science in need of further research.

As easy as the book is to read, or listen to, there is a sense that some material here is designed to signpost for undergraduate students areas they might take their future studies. History books do this all the time, and it is fun to see it in the context of biology. Foster has a great deal of wit in his writing, and the cadence with which he delivers his own narration is frankly superb. Around chapter 10, the focus of the book begins to narrow in on specific subjects, and it is here where many more casual readers may begin to find their interest slipping. Drugs, food, exercise and current academia are all areas people would likely want to know more of, but for some reason the subject matter landed a lot less smoothly in these chapters than earlier entries.

Admittedly, part of the difficulty is personal. I expected this to be a lot lighter than it was, and my concentration was not on form. Fortunately, tis was not because of a lack of sleep and Foster's excellent detailing of Sleep Circadian Rhythm Disorders (SCRD) helps to illuminate some of the issue people struggle with when it comes to sleep. One of my favourite things was that, towards the end of the book, Foster posits that one day people might well regard those machismo 'only slept four hours' boasts, with the same contempt they currently treat smoking. The meaning behind this is that the work patterns encouraged by modern capitalist economies are not only individually disastrous, but actively bad for the economy. They lead to poorer attention spans, bad decision making and a collapsing work force.

Probably the highlight takeaway from the book is this; everyone is different, and it is up to the reader to decide what sleep patter works for them. But we all exist, in a way, around light, and it is non sensical to pretend that we can so greatly shift our body clock to do without the sun. Night shifts are not only bad for people's health, they are bad for their relationships, and Foster's best chapter may be on this very subject. Moreover, light exposure from our phones, as contrary as this seems, is not as bad as everyone seems to make out. What is actually happening, is that it increases our alertness and not particularly impeding our body clocks as much as was previously thought. So if you want to read an e-book before bed, or feel more comfortable after browsing fo a few minutes, do not go beating yourself up about it. Proper sleep patterns are far more influenced by stress, diet, duration and light exposure throughout the day, than anything that fits inside of our pocket.

My takes on Foster may not be wholly correct, but that is the joy of having a book to discover for yourself. It is well worth reading, though any potential reader should brace for a far more analytical book than might be otherwise expected.

[Tana · Rating 4 out of 5]

Lighter and easier to read than Why We Sleep: The New Science of Sleep and Dreams by Matthew Walker which is brutal. That said there's loads of random facts in here, some are interesting and some pages just seemed unnecessary.

Chapter 1: The Day Within discusses the 24-hour cycle. Circadian rhythm and the main Chronotypes, such as larks and owls.
Diurnal animals: humans, deer and dogs
Nocturnal animals: mice, bats, owls

Chapter 2: A Heritage from Our Cave Days
In Greek mythology, Hypnos is the God of Sleep. He is the son of Nyx (night) and Erebus (darkness) and his twin brother is Thanatos (death). They live in the underworld (Hades). So even in ancient time sleep has been linked to darkness, death and hell.
Thomas Edison (electricity dude) considered sleep as waste of time.
There's difference type of sleep, not just REM and NREM but also deep sleep and slow-wave sleep (SWS), which we progressively move from stage 1, 2 & 3 and then reverse.
NREM sleep is linked with our ability to form memories and problem-solving. We dream in both REM & NREM but it's longer and more intense in REM sleep. Depriving people suffering depression REM sleep can improve their condition short-term, but makes it worse long term.

Chapter 3: The Power of the Eye
Page 51: "In the 4th century BC, Plato argued that we are able to see because light emitted from the eye and that this light seizes objects with it's rays. This was the "extramission" theory of vision, and as bizarrely as it seems to us today, until the 1500s this was the widely held view in Europe of how the eye worked. To his credit Aristotle (384-322BC) was one of the first to reject the extramission theory of vision, arguing in favour of the "intromission" theory, whereby the eye receives light rays rather than projecting light into the world. Sadly, this eminently sensible theory from the ancient world was not embraced. Even Leonardo da Vinci in the 1480s first supported the extramission theory, but after dissecting the eye in the 1490s, he switched to the intromission theory. early observations by Islamic physicians, notably Hasan Ibn al-Haytham, who lived from 965 to 1040 AD and is known in the West as Alhazen, documented that the pupil dilates and contracts in response to different levels of light and that the eye is damaged by strong light. He used these observations to argue correctly that light enters the eye and that light is not emitted from the eye."


Chapter 4: Out of Time
Weight Gain & Obesity: high levels of cortisol (stress hormone) can lead to weight gain, because "cortisol mobilises the liver to produce more glucose, but if the glucose is not metabolised it gets converted into stored fat in fat cells (adipose tissue)... cortisol directly alters appetite sensitivity and increases the cravings"

Social jet lag, a term developed by Till Roenneberg, is what people suffer if they are either living on a Western edge of a time-zone (book doesn't explain what location that is), or from Daylight Savings hours (created by Germans originally to ration coal), or due to social/work demands we sleep irregular hours.


Chapter 5: Biological chaos
Lists the difference sleep disorders and issues from sleep-walking to obstructive sleep apnoea (OSA) and advise on what can be done for it.

Chapter 6: Back in the Rhythm
Tryptophan an amino acid, may aid sleep as it's a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3. Full fat milk has Tryptophan.

No one exactly knows why we yawn.

Kava (plant) might help sleep but we don't know the long-term consequences (not enough research).

Benzodiazepines, which was discovered accidentally by Leo Sternbach in 1955 who worked for Hoffmann–La Roche after escaping the Nazis. The first was chlordiazepoxide (Librium)), then diazepam (Valium).
There's also Z-drugs (zolpidem, zaleplon and zopiclone).
All of these drugs work to enhance GABA release (the neurotransmitter gamma-aminobutyric acid), but have long-term use problems. People are instead encouraged to try CBTi: cognitive behavioural therapy for insomnia

The male praying mentis has his head eaten while mating (doesn't stop the act) and then the female eats the rest of him. Poor sod.

Women are more likely to wake up early. Menstrual cycle can change sleep and mood (is there a causation). No evidence the moon influences the Menstrual cycle. Menopause can cause insomnia/poorer sleep. Estrogen's and testosterone play a part in male and female sleep patterns.


Chapter 8: The Rhythm of Life
Men and women are biologically different- they are broadly "sexually dimorphic", and this extends to several notable differences in our circadian system.
...oestrogen in females has been linked to more consolidated circadian rhythms with a greater amplitude... more robust circadian rhythms... as women age oestrogen levels decline... age related-insomnia increase of insomnia reported by many women.
Menstrual cycle can impact mood and promote SCRD.

Chapter 8: The Seven Ages of Sleep
There is evidence that young adolescents show increased sensitivity to evening light, and this helps shift adolescent clocks to a later time... elderly people show a decreased circadian photosensitivity to dusk light... One suggestion for this decline... problems such as cataracts.

As we age we become more morning types and our sleep duration reduces... Even our urine production changes.

Chapter 9: Time Out of Mind
3 elements to Cognition:
1.Attention: notice key features in the enviroment and filter out "irrelevant" information
2.Memory: ability to retain and retrieve information, initially as a transient memory before it becomes set into long-term memory
3.Executive function: ability to plan, monitor and then control complex behaviours that achieve specific goals or enable us to complete specific tasks

1.Attention: is particularly to sensitive to sleep loss, e.g. the 1986 Chernobyl disaster was due to sleep loss. Exxon Valdez oil spill caused by sleep deprivation. The 2001 Selby train crash in the UK was due to Gary Hart falling asleep at the wheel of his Land Rover and crashing into the tracks of the railway due to a microsleep.

2.Memory: is divided into 3 processes and is aided by sleep.
i. acquisition: encoding, memory is formed but at risk of being forgotten
ii. consolidation: gradually turned into long-term memories. 2 types of long-term memories, declarative (conscious control) & procedural (how we perform actions) memories.
iii. retrieval: recall of the memory

3.Executive function: people sleep on a problem has helped problem-solving, e.g. Nobel Prize winner Otto Loewi woke up with the idea on his theory of chemical neurotransmission. Dimitri Mendeleev and his periodic table, August Kekule and benzene molecule, and Beatles legend Sir Paul McCartney woke up one night of sleep in 1964 with the melody for "Yesterday" fully formed.

SCRD and depression has links.

Chapter 10: When to Take Drugs
when really unwell and various illnesses described here.

Chapter 11: A Circadian Arms Race
We now appreciate that every aspect of the immune response is being regulated by the circadian system. The skin is one of the most important, but most overlooked, parts of our immune defence... providing an effective barrier.
The circadian system plays an important role in skin porousness (permeability). Permeability is increased in the evening and at night, and lowered in the morning and during the day. This means that there is more water loss in the evening, which is why we feel more skin itchiness towards the evening and night as our skin dries out which can lead to more chance of disease. But we also have more blood flow during the night to help fight them. Loads of STIs and infections go rampant. Sleep breaks down our immune response and the infections impact our sleep causing further infection.

Chapter 12: Eating Time
metabolic syndrome is the medical term for a combination of diabetes, high blood pressure (hypertension) and obesity.

People who don't sleep much crave sugary snacks for a burst of energy which can lead to diabetes.

Chapter 13: Finding Your Natural Rhythm
We evolved with very little sugar in our diet. Chemically refined sugar was most probably first produced in India around 3,500 years ago and spread east to China, West through Persia and the early Islamic World reaching the Mediterranean in the thirteenth century.


Chapter 14: The Circadian Future
The value of sleep is being acknowledged.

Page 330: appendix at the end measuring sleep is great!

[Cathy · Rating 3 out of 5]

Although the book’s sub-title, ‘The New Science of the Body Clock, and How It Can Revolutionize Your Sleep and Health, might give the impression this is purely a self-help book in fact it’s a detailed account of the current thinking, based on scientific research by the author and others, about the effects of the body’s circadian rhythms – the so-called ‘body clock’ – on sleep, physical and mental health.

If I had to place the book on a scale between popular science and academic text, I’d say it tends more towards the latter although the ideas it contains are expressed with clarity and precision.  Some chapters go into more depth than others and I’ll confess there were some sections I skipped entirely because of their complexity.  There are detailed diagrams with even more detailed notes providing supplementary or explanatory information. With a few exceptions, I would say it’s not necessary to read all the additional information in order to understand the concepts the author is discussing or the propositions he is examining. For those wary of embarking upon a book of nearly five hundred pages, over a hundred pages are taken up by appendices, references and index.

Life Time is full of fascinating information and you get a real sense of the author’s passion for his subject. I certainly learned a lot about how much of our body’s functions are influenced by circadian rhythms, everything from saliva production to control of appetite, and how disruption of our body clock can have an impact on our sleep, our cognitive ability, our physical and mental health, even the effectiveness of medication. The book focuses a lot on the impact of sleep and circadian rhythm disruption (SCRD), especially in relation to night shift workers. For example, that this is likely to have been a factor in the accidents at the Three Mile Island and Chernobyl nuclear plants or the Exxon Valdez oil spill.

If this is all sounding a little heavy, there are moments of humour. For instance, at the end of each chapter the author includes examples of questions he has been asked at talks and lectures he’s given. My favourite was, ‘If we shouldn’t eat at night, why do they put a light in the fridge?’. Actually, the author demonstrates that there is scientific evidence for what we call the ‘munchies’.  He also provides some useful, and often amusing, analogies. For example, when discussing the relationship between SCRD and stress, that stress is ‘a bit like the first gear of a car engine – it provides rapid acceleration – which can be very useful short term. But if you keep the engine in first gear for a long journey you will destroy the engine’. Or, when discussing the key elements of cognition, that essentially our ‘executive functions are the processes in the brain that allow us to solve problems – like E=MC² – or for most of us, how to turn what we find in the fridge into dinner’. He also demonstrates there is science behind the old adage that you should sleep on a problem.

The book ends with a ‘call to arms’, for more communication about the impact of sleep deprivation on education and employment, especially healthcare, and the actions that can be taken to mitigate this.  My main takeaway from the book is summed up by the author’s comment that ‘what we do when really matters’.

[Richard Thompson · Rating 4 out of 5]

There's a lot of information here - some that I already knew but a lot of new things too, more than I can possibly remember. I was happy to learn that I am mostly doing it right - taking my meds at the right time of day, sleeping well enough that I don't have to worry, exercising at the right time of day, scheduling important conversations for mid to late morning.

I didn't know that we have special cells in our eyes (not the rods and cones) for detecting dawn and dusk and that this form of visual perception is closely tied to the correct resetting of our daily rhythms. I didn't know that our gut biomes have circadian rhythms that are synchronized to our own. I did have a good general idea of the various kinds of sleep disorders and their connections to physical and mental illnesses, but there were a lot of details and new developments that updated my knowledge.

Since all of us sleep and all of us sometimes have trouble sleeping, this is a book for everyone.

[Willow Anne · Rating 4 out of 5]

This was super interesting! It's the nonfiction book I didn't know I wanted to read until I read it. I started it hoping it'd shock me into going to bed earlier, because I'd been staying up way too late when I started this (mainly because of reading heehee). And it kind of worked I suppose, because I've been doing much better lately at getting to bed within my goal hour (10pm). So here's all the quotes I noted down:

"Light around sunset (dusk) delays the clock, so we go to bed later and get up later the next day. Light around sunrise (dawn) advances the clock so we go to bed earlier and get up earlier the next day."
It took me a while to wrap my head around this one, and I still have to do some serious thinking to fully understand, but this point seemed pretty important throughout the book so I wrote ot down.

"Adolf Hitler was a notorious insomniac, and would finally fall asleep in the early hours of the morning. [He] was fast asleep at the Berghof when the Allies invaded France on D-Day on 6 June 1944. His generals would not send reinforcements to Normandy without [his] permission, and no one dared wake him, so he slept until noon. The delay is thought to have saved many lives and been critical for the Allied invasion"
Who knew? Why don't they teach this in history?

"Combining a regular sleep schedule, a bedtime routine that promotes sleep, and morning light exposure really helps"
I don't remember what this was supposed to help with, but I'm just gonna go ahead and assume I can insert 'keep your sleep schedule on track'?? Maybe? I could go back and look to see how the sentence ends...or I could just keep writing this review...

"the tired brain has an even greater preference to remember negative, over positive, experiences."
So a lack of sleep makes you more pessimistic and can lead to mental health issues. This is such an important point! I really like this, and just that reminder, that a lack of sleep makes you more negative, is such a good motivator to get some sleep. Because I just wanna be positive all the time. Also I'm telling you, this book is great to read at night. It encourages me to get to bed and not stay up forever reading.

"A recent study showed that total sleep deprivation after learning a task resulted in much poorer task performance, and, significantly, performance was not improved by an afternoon nap, or by increased practice of the task."
Yikes. Guess i better get some sleep.

"[Headache] triggers include stress, abnormal meal timing, the menstrual cycle, abnormal light exposure and SCRD"
This is just good to remember. Not enough sleep? Headache. (Eating at weird times? Headache.)

"ensuring that individuals have had sufficient sleep can enhance vaccine effectiveness"
Gotta remember this one when I get my booster so I can get some sleep the night before!

"During morning exercise, before breakfast, the body is still using stored fat as fuel, and so exercise at this time of day will burn more fat."
Ok, this blew my mind. I never thought about it like this before! Which is why morning exercise can be so effective!

"One final tip is that if you walk for 30-45 minutes after an evening meal, rather than before, this can assist in the control of blood glucose and hence weight loss."
Hey hey hey! Let's do it!

"sleep loss is associated with increased release of the 'hunger hormone' ghrelin from the stomach and reduced release of the 'satiation hormone' leptin from adipose tissue."
This isn't the best quote to end on, but science! Actually, something I really liked about this book was how deep it got molecularly. It was really interesting to read about, even if it did take me a few reads to understand it all.

This wasn't a fast read, but I kind of liked it that way. It made the effects (me getting to bed sooner) last longer, and I'm hoping that'll continue even now that I'm finished with it.

Overall I'm really happy I read this and I hope I remember the things I've learned and keep applying them so I can get better sleep. Because one of the main points I got from this was how much of your life sleep can really affect, anything from health to mood to your outlook on life that day. So if I want to have a positive outlook and a good day everyday, I just have to get enough sleep.

[Nienke · Rating 5 out of 5]

Vastly interesting. A must read.

[Monika · Rating 2 out of 5]

For a clearer, more approachable, and comprehensible breakdown of sleep science I would recommend skipping this book and turning instead to Matthew Walker's Why We Sleep. Around 75% of the book tackles the same topics, with the same conclusions; SLEEP SLEEP SLEEP!

A couple of minor points do differ: Foster suggests use of Tryptophan-containing foods to boost serotonin and melatonin levels, helping both sleep and mood (glass of whole milk before bed? yes please). He also refutes the idea that it is the blue light from our devices that keeps us awake, but rather the whole stimulation effect of playing on a computer (absence of evidence in not evidence of absence). For my part I begrudge Foster for this revelation as it is easier to follow a recommendation if there are multiple reasons for doing so (and now I've lost a reason to not look at my phone before bed, which I'm sure doesn't help).

Foster's narrative style was ingratiating and a little annoying for another thing (though this should not deter others. I find most popular science authors annoying). By the end one is under the impression that schizophrenia and other psychotic disorders are as common as headaches, so keen was he to give tailored-advise to this *apparently massive* strata of society. Obviously this was for entertainment purposes (what ISN'T entertaining about bipolar eh?) but this meant that his advice was often useless for the general reader.

Foster is not a clinician. This is quite clear. He has this bizarre, amusing, and frankly insulting idea that doctors are completely formed after medical school. He implies on a number of occasions that your GP or hospital clinician could not have the foggiest clue about sleep science because it is not an integral part of the medical school curriculum. Give me a break. As if, after the age of 22 the medical brain is impermeable to all other information. Doctors couldn't possibly begin to advise pharmaceutical companies because God-forbid they ever attempt to read a paper that wasn't explained to them in second-year physiology. It's laughable. Medical school is, in actuality, like a preparatory pre-school for the school of intensive medical formation that continues up until, well, a doctor's... death.

(And then there's the bit where he bangs on about how nocturia can keep you up at night (terrible), and then advises his previously maladvised clinician colleagues to prescribe all of their patients their DIURETICS before bed.)

It's not just medical students. Foster (like Walker in fairness) has his intellectual baby. He thinks that sleep science should change the face of the school curriculum:

"If the topic of sleep is taught at all, it is through the efforts of dedicated teachers, who try and carve out a few hours in the gridlocked national curriculum. And this is not easy. Appropriate and standardised materials are lacking, and support from headteachers is often lukewarm, chilled by the constraints of the National Curriculum which does not include sleep education »

And while I probably agree that sleep education would be more welcomed and appropriate in primary schools than say... sex education, let's be a bit more realistic.

[Roland Glotzer · Rating 4 out of 5]

This book is very informative while also being practical in how to manage the body clock e.g when to take specific medications, best time to eat or exercise, best time for vaccinations, etc..

While the information provided deserves 5 stars I only gave it 4 stars as it is written more like a textbook than a regular book albeit with a dose of anecdotes and humour. Books like “Why we sleep” by Mathew Walker may be more accessible to a wider audience.

The summary tables and charts are very useful but it could have been advisable to add as well an appendix with the numerous acronyms used in the book (they are explained the first time they are encountered but 50 pages later you may not remember and need to go back looking for the explanation).

[Liz · Rating 4 out of 5]

Very interesting! I really enjoyed this and once again am reminded of why I prioritize sleep.

[Meana · Rating 3 out of 5]

3.5 to be more accurate

I liked reading it and it was very useful, goods and bads:

- Easy to read and understandable for most of it but some parts do get more scientific and the reading becomes difficult. I think it was an audience that is too wide, it aims to be a book for non scientific audience but at the same time includes parts for a scientific audience and the mix is not great.

-The weight of mental and psychiatric disorder related topics is too much for a general audience book. I would find better to give more focus to exercise, nutrition, other more common topics than to mental disease. Mental disease is important in society but there would be more benefit for the general audience in the other topics and while interesting, I felt that (luckily) there was not a lot I could apply from those sections.

-Very interesting topic and I like the approach of the book of finding your own way and no one size fits all. I am very interested in circadian rhythms and definitely got better understanding with this book.

[Clowd · Rating 4 out of 5]

I loved this book 🙌🏻 It was super easy to read even though it contained so much scientific information. The language Russell Foster uses in his book is pretty much conversational. Although I’ve learned so much new information about the way sleep and circadian rhythm affects all aspects of our lives, I wish there was more stuff on exercise and food. There are a few chapters dedicated to this topic but it’s mostly things I’ve already known.

[Tom McCluskey · Rating 4 out of 5]

Excellent book, unbelievably well researched (922 references!!) and extremely accessible.

I’m going to be insufferable talking about all the things I’ve learnt from it. At any moment I could break into a lecture about Sleep and Circadian Rhythm Disruption (SCRD) so watch out.

I’d recommend this book to Lucy, she likes her Fitbit showing her her sleep so why wouldn’t she absolutely love reading this?

[Tariq Mahmood · Rating 5 out of 5]

The circadian clock is a universal entity familiar to all natural living beings from the cellular level to the giant whales of our world. It would be foolish to ignore its rhythms, yet we have chosen to disregard them. This book is pivotal in highlighting the importance of circadian rhythms in our lives, it is a start but a very important step in the right direction.

[Max Deacon-Thomas · Rating 5 out of 5]

A really interesting read - lots to learn, but written in a way that's digestible and memorable to a layreader. Definitely recommend that everyone thinks about how to ensure their circadian rhythm is healthy with enough sleep. But this won't mean the same for everyone, so have a read to find out more...

[Felicity Hallam · Rating 4 out of 5]

I do think that this book is extremely well written and I do really like his style of writing and the way he explains concepts. This book is super science heavy is my primary issue with it. Obviously if you’re into that, this book will be great for you. But if you struggle to understand science like me, this book becomes quite a hard read in the second half of

[Gijs Limonard · Rating 4 out of 5]

A solid overview of the circadian rhythms of the human body; as to be expected heavily skewed towards sleep, but also some good bits on circadian rhythms as they relate to immune function and pharmacodynamics; the text would benefit from some more storytelling, to counterbalance the academic style the author can’t seem to write himself away from.

[Regina Barata · Rating 4 out of 5]

Um livro que nos informa sobre as mais recentes descobertas no estudo do sono e do seu impacto nas nossas vidas, a todos os níveis. Abrangente e bem fundamentado (com uma lista enorme de referências), o autor vai desvendando alguns dos mistérios que envolvem este estado fisiólogico e alerta desde o início para a importância do respeito pelos ciclos circadianos e pelas horas de descanso.
Indispensável para quem se interesse pelo tema ou tenha preocupações com o seu bem-estar geral.

[Matthew Berry · Rating 4 out of 5]

Russwll Forster is a Professor of Circadian Neuroscience at Oxford, and in this book, he goes through years of research in the field. Life Time provides strong evidence that societal shifts towards performing daily routines at night are detrimental to our health. To quote the last chapter, "circadian rhythms are embedded within every aspect of our biology, and we ignore this rhythmic biology at our peril." The book is firstly an explanation of the biology behind sleep and circadian rythms, and then the rest of the book covers disorders and the consequences of them, which horribly include a higher risk of cancer, diabetes, dementia, and mental illness. It will not make for nice reading if you are a night shift worker and airline crew, or, interestingly, if you live on the western edge of a time zone (he terms this social jet lag).

I have been obsessed with getting 8 hours of sleep for the last few years, and this has only strengthened my resolve! Really accessible and informative; references are peppered throughout if you want to research the subject further.

4.5 stars.

[Luca Jones · Rating 3 out of 5]

I sleep well so in hindsight this book wasn’t a great selection on my part. Parts were interesting and informative (probably even more so if you’re insomniac) but I did start skimming by the end.

[Rob Hopkins · Rating 3 out of 5]

More of a literature review on sleep than a "here's what you can do about it" type book. Interesting in places but ultimately repetive: poor sleep = really bad for you. It'll give you cancer, schizophrenia and make you fat. Some interesting new insights around chronopharmacology and how taking medication at the right "circadian" time can drastically increase it's efficacy.

[Warren Berkson · Rating 4 out of 5]

A lot of repetition, but as a result of the book and research of major medical web sites, I’ve changed my medication schedule from AM to PM. It’s supposed to be more effective with fewer side effects. Also his research indicates that having a vaccination in the morning produces 3 times more antibodies than an afternoon vaccination.

[Anastasia Bizyayeva · Rating 3 out of 5]

This was kind of fine - and took me a long time to get through it because I didn't love the book. I'm very interested in circadian rhythms/ health optimisation generally, but it felt like there was a lot of padding in this book. Specifically, when it came to things like sleep disorders or mental disorders accentuated by circadian rhythm issues, the author went through an exhaustive and very-specific list (like multiple kinds of sleep apnoea).

It ultimately felt like this book was for everyone and so was for no one. I found myself skipping sections that covered recommendations for the elderly to maintain good sleep hygiene when they need to urinate in the night and things of that ilk. It felt like there was a great, much smaller book in here that could be universally interesting to those who just want to learn about circadian rhythm, and those intensely specific examples and recommendations could've been supporting blog posts.

[Frederic · Rating 5 out of 5]

A wonderful journal into the world of sleep and our circadian rhythm. A refreshing melange between scientific evidence and real-world applications to improve one's sleep and life cycle. A must-read for everyone who values sleep.

[The Contented · Rating 5 out of 5]

Read or listen to this book. It could save your life, or at least improve its quality tremendously

[ErnstG · Rating 2 out of 5]

For all the author's undoubted knowledge, I never could understand who the book was written for. Not for me, I think, perhaps because there is too much general background not applicable to me.

[Ava Cadenhead · Rating 2 out of 5]

This read a bit more like a scientific textbook to me than the self help book that I was expecting. Still quite interesting but just not what I expected.

[Steve · Rating 4 out of 5]

"Life Time: Your Body Clock and Its Essential Roles in Good Health and Sleep" by Russell Foster is a compelling exploration of the intricate workings of our circadian rhythms and their profound impact on our health. Narrated by Foster himself, the audiobook offers an engaging and authoritative voice that guides listeners through the complex science of our biological clocks.

Narration and Presentation

One of the standout features of this audiobook is Foster's narration. As a leading expert in circadian neuroscience, his deep understanding of the subject matter shines through. His delivery is clear, articulate, and infused with a passion for the topic that makes the scientific content accessible and engaging. The personal touch of having the author narrate his own work adds an extra layer of authenticity and connection, making the listening experience both informative and enjoyable.

Content and Structure

"Life Time" is meticulously structured, taking listeners on a journey through the science of circadian rhythms, sleep, and health. Foster begins by laying a solid foundation, explaining the basics of circadian biology and how our internal clocks are synchronized with the 24-hour day-night cycle. He delves into the history of circadian research, highlighting key discoveries and the scientists behind them.

The audiobook is divided into sections that cover various aspects of circadian rhythms and their influence on different facets of our lives. Foster discusses how our body clocks regulate sleep, metabolism, immune function, and even mental health. He provides a comprehensive overview of the mechanisms that drive these rhythms, from the molecular level to the behavioural level.

Scientific Rigour and Accessibility

Foster's expertise is evident in the depth of scientific detail he provides. He explains complex concepts with clarity, using analogies and examples that make the material accessible to a broad audience. For instance, he likens the circadian system to an orchestra, with different "instruments" (genes, proteins, cells) working in harmony to produce a coherent "symphony" of physiological processes.

Despite the scientific rigour, Foster maintains a conversational tone throughout the audiobook. He avoids jargon and breaks down intricate ideas into digestible pieces, ensuring that listeners without a background in biology can still grasp the key points. This balance between depth and accessibility is one of the book's greatest strengths.

Practical Insights and Applications

Beyond the scientific explanations, "Life Time" offers practical insights and advice on how to align our lifestyles with our body clocks for optimal health. Foster emphasizes the importance of regular sleep patterns, exposure to natural light, and mindful eating habits. He provides actionable tips on how to improve sleep quality, manage shift work, and mitigate the effects of jet lag.

One particularly valuable aspect of the audiobook is its focus on debunking common myths about sleep and circadian rhythms. Foster addresses misconceptions such as the idea that everyone needs eight hours of sleep or that night owls are simply lazy. By presenting evidence-based information, he empowers listeners to make informed decisions about their health.

Impact and Relevance

In today's fast-paced world, where technology and modern lifestyles often disrupt our natural rhythms, "Life Time" is a timely and relevant work. Foster highlights the consequences of circadian misalignment, such as increased risk of chronic diseases, mental health issues, and reduced cognitive performance. He underscores the importance of respecting our body clocks and provides a compelling argument for why we should prioritize circadian health.

The audiobook also touches on broader societal implications, such as the impact of shift work on public health and the need for policies that promote circadian-friendly environments. Foster's call to action is clear: by understanding and respecting our body clocks, we can improve not only our individual health but also the well-being of society as a whole.

Conclusion

"Life Time: Your Body Clock and Its Essential Roles in Good Health and Sleep" is a masterful blend of science, storytelling, and practical advice. Russell Foster's expertise and passion for the subject make this audiobook a must-listen for anyone interested in understanding the vital role of circadian rhythms in our lives. Whether you're a science enthusiast, a health-conscious individual, or someone simply looking to improve your sleep, this audiobook offers valuable insights that can help you live a healthier, more balanced life.

[Hazel Bright · Rating 2 out of 5]

While the author provides some excellent information about the importance of sleep and circadian rhythm disruption (SCRD) and its health and economic impacts on individuals and on the general public, the author completely disregarded one key issue of interest to me, namely, what causes night eating syndrome (NES) and how to address this issue. Given the fact that millions of people suffer from NES (1.5% of the population), this is kind of a glaring omission. The lack of information on this subject is made worse by the fact that a) Foster does discuss sleep related eating disorder (SRED), which is similar to NES, but is much less common; and b) Foster describes a study that touched on NES - an analysis where mice were fed only during the day (their night) and they developed mousy NES while their other bodily functions remained nocturnal. He also describes the dialogue between gut bacteria and appetite in the context of night shift workers, another opportunity to discuss NES, but he assiduously avoided discussing the syndrome. It seemed almost cowardly.

Additionally, the author goes into a long discussion about cholesterol buildup and how statins work to reduce levels of cholesterol in the blood. He then describes the optimal time to take statins. He neglects to mention that numerous studies report absolutely no reduction of overall mortality when statins are prescribed (as in the majority of cases) as a prophylactic measure against heart problems in high-risk individuals. See Ray et al (2010), "Statins and All-Cause Mortality in High-Risk Primary Prevention: A Meta-analysis of 11 Randomized Controlled Trials Involving 65,229 Participants." From that paper, "Conclusion: This literature-based meta-analysis did not find evidence for the benefit of statin therapy on all-cause mortality in a high-risk primary prevention set-up."

These rather egregious missteps reduce the credibility of the work in its entirety for me, unfortunately. I would like to have confidence in what I learned from this book, but alas, I do not. When he discussed subjects upon which I am informed, he missed the major point, which, for statins, is that they may reduce your cholesterol levels, but unless you have a clinical history of coronary heart disease, they won't lengthen your life, and for NES he provided nothing at all.

The writing was clear and engaging, if a bit repetitive at times. Not a bad book, but disappointingly flawed.

[Zhuo Zhang · Rating 4 out of 5]

The 2017 Nobel Prize in Physiology or Medicine goes to the discoveries of molecular mechanisms controlling the circadian rhythm, which is very much similar to the basic principle of traditional Chinese medicine. SCRD has been the core word throughout the book as the author has stated the importance of circadian rhythm and the harm due to the disruption of it. SCRD could cause the various impacts of emotional function, impairments in cognitive performance and increase of physiology and health risk. The author has emphasized significantly on sleep more than the necessity of it. It is appalling to find out the lack of sleep could cause such a negative impact to all aspects of our everyday life. (Here recommend a book Why We Sleep: Unlocking the Power of Sleep and Dreams). He also suggested some optimal time for eating(no big meal for dinner, especially before bed), exercise (rule of thumb: no exercise before bedtime, 4-6pm is optimal for performance, morning exercise on empty stomach burns more fat), sexual life, and taking drugs etc. He also mentioned that light has played another important role in our circadian rhythm, and how we can use light to help us to overcome annoying jetlag. In a nutshell, we need respect our circadian rhythm, which is all about timing itself. "The lives of both wise and foolish people all end in death, but in the content of this book the circadian wise will, on balance, live longer, be happier and learn more fulfilled lives.

The book has provided a very clear structure about circadian rhythm and the science of it need to be more taught among people, especially students.

[Alicia Bayer · Rating 2 out of 5]

I slogged through half of this very long and dull book before finally giving up because the author kept saying things with authority that I knew to be false and I finally started questioning whether I could trust much of what he was saying that I hadn’t purposely researched already. For instance, he regurgitates the myth that all praying mantis females bite off the males‘ heads during copulation. We have known for decades that only a fraction do this. He says that timing of intercourse related to ovulation has no bearing on the gender of the baby. It’s pretty well established that that’s not true (the book Taking Charge of Your Fertility is older but fascinating to start). When he started talking about PMS and menopause I was just out. There’s only so much that a man who has no life experience or work experience should spout off about, and looking up studies done by other men is not enough. Same when he said there was no proof that weighted blankets were helpful for autistic kids. Just because someone didn’t publish a study he approves of doesn’t mean he gets to proclaim it untrue. And what does that have to do with circadian rhythms anyway? It felt like he considered himself an expert on literally everything.

The book just felt like it was never going to end and had so little actually helpful advice. I also got tired of him talking about what his crowds of people always ask about. It felt very much like he repeatedly was trying to prove how famous he was or what an expert he was. A miss for me.

I read a digital ARC of this book for review.