Review of Why We Sleep by Matthew Walker


You’d be hard pushed to find anyone that understands sleep as deeply as Matthew Walker.

As a neuroscience and psychology professor at the University of California, Berkeley, he runs the Centre for Human Sleep Science there. Matthew Walker is high-profile in the media. He is a popular guest on high profile podcasts, and now hosts his own.

His book ‘Why We Sleep’ is a mix of actionable advice, background science and fascinating ‘nuggets.’

It took me a while to read it.

While the tone is light, Why We Sleep is information dense.

Why We Sleep is an academic book made conversational. While the conversational tone worked, there are long passages of long sentences to navigate. Matthew Walker is a huge fan of the comma.

My impression was backed up when I asked my good wife what she thought of it. ‘I got around 30% through, and then got bogged down,’ summed it up perfectly.

I’m tenacious – and was rewarded with multiple fresh perspectives on the fascinating science of sleeping.

So many, that drilling down into just five take-aways was more difficult than usual.

Why We Sleep Book Review

Review of Why We Sleep by Matthew Walker – My 5 Key Take Aways


#1 – Sleep Cycles are Not Symmetrical

I thought I understood the differences between REM and NREM (Slow Wave) sleep.

Turned out that I only knew a simplified version. The deep dive into the four levels of NREM sleep, and asynchronous balance between NREM and REM during a 7 hour+ night was fascinating.

Descriptions of the neuroscience of each part of the sleep cycle brings this to life. Functions of sleep include memory formation; cleaning of toxic build up from the brain and emotional regulation.

When you see the value of each part of the sleep sequence, you won’t take missing sleep lightly.

#2 – Why We Sleep Review: Missing Sleep is More Damaging Than You Think

Missing sleep is dangerous.

Not only for driving or operating machinery. Missing sleep is horrific cognitively, emotionally, and physically.

Walker covers study-after-study. While this section of the book did get dry after a while, the message of how quickly our functioning deteriorates is eye-opening.

Just a handful of consecutive nights of short (6 hour) sleep affect driving more than being over the legal blood alcohol limit. Our ability to reign in emotional outbursts nosedives after short sleeping, and memory is devastated by just a single missed night of sleep.

What this section highlighted for me was how short-sleeping has become the ‘tough’ thing to do – especially in jobs like banking.

It is not only damaging mentally, but it also wreaks havoc on your immune health.

A clinical trial with cold viruses highlighted this. People with good sleep were infected less frequently than those with shorter sleeps. There are clinical links between sleep and brain health (dementia and Alzheimer’s included).

Skipping Sleep is Dangerous

#3 – Why We Sleep Review – Evolution and Sleep (Flipping My Worldview)

If there is something I love, intellectually speaking, it is a fresh new angle.

Matthew Walker provided an exceptional example. His look at evolution, sleep and the tree of life is fascinating. REM sleep has evolved separately in multiple branches. Sleep is universal. Even night owls vs early birds have an evolutionary explanation.

Sleep appears costly. Over millions of years of evolution, traits which would appear a lot less debilitating (in terms of hunting and reproductive success) have been wiped out.

The view-flipper went like this: Rather than ask ‘what is the evolutionary purpose of sleep?’ We can ask ‘What is the evolutionary advantage of being awake?’

In other words, is being asleep the default state of all life?

I won’t go down the rabbit hole in this review. This view-flip is up there with my 16-year-old-self reading ‘The Selfish Gene’ in the late 1980’s in terms of frameworks to ponder.

#4 – Say No to Sleeping Pills and Coffee – The Value of CBT-I

I’m sneaking two take aways here. The first is the link between adenosine and caffeine. I realised that (like everyone!) the link between caffeine and alertness was clear. It was only after reading Why We Sleep that I realised I did not know anything about the mechanism of this.

Adenosine builds throughout the day. This chemical creates sleep pressure as we move into the evening. Caffeine blocks its cellular receptors. Together with melatonin, adenosine is vital to our daily cycle.

Alongside antibiotics, the prescription of sleeping pills highlights the ‘whack-a-mole’ (or ‘whack-a-symptom’) approach to medicine. Matthew Walker explains how newer varieties are better than those from decades ago – though still dangerous.

The reason is that sleeping pills are sedatives.

They fight insomnia in a parallel way to alcohol. You’ll drift off, but into a shallow version of sleep – neurologically speaking. Without the benefits of deep sleep, your memory, immune system, and energy levels will never recover.

Cognitive behavioural therapy has replaced sleeping medication as the go-to for doctors in the USA. CBT-I stands for ‘Cognitive Behavioural Therapy for Insomnia.’ It is a series of behaviour changes and thinking habits, which get people back on track with sleeping.

More on CBT-I in a separate article here at the Age Well Times.

Coffee Sleep and Ageing

#5 – Simple Sleep Tips Boost the Quality of Your Life

Missing sleep is dangerous, though improving the quality and duration of it is simple.

While many of the good sleep habits covered in this section are ‘obvious,’ they take on a new importance after reading so many studies of how bad / short sleep messes with your brain and body.

The link between exercise timing and sleep is another example of something I already knew – but did not understand from a physiology perspective. Our core body temperature is lower during sleep, and exercise raises it – something to avoid in the few hours before bed.

Managing food, caffeine and alcohol are important to sound sleep. So is having a routine, a dark and cool sleeping area and avoiding blue light in the hours before bed.

A new one for me was not to stay in bed awake.

If you do have problems falling asleep, Matthew Walker advises getting up again quickly (within 20 minutes). You can then do something relaxing like reading and return to bed when you feel tired. This leads to a stronger association between your bed and being asleep.

Reviewing Why We Sleep Wrap Up

Wrapping Up: Why We Sleep Review – Making Sleeping Your Bedrock Habit

I knew that sleep is the bedrock health span habit before reading Why We Sleep.

After finishing it, I realise that I was on the right track – though not tough enough.

By creating a best-seller on the topic, Matthew Walker has poured cold water on the culture of short sleeping that damages medicine, banking and so many other areas. There is nothing weak or ‘soft’ about getting eight hours sleep a night. This leads to better performance, decision making, emotional resilience and health.

If you prioritise sleep quality, the other habits needed for a longer healthier life become much easier.

This book has already helped me sleep better. I recommend you read it (overly long sentences aside) and prioritise your own sleep.

You’ll find Why We Sleep at Amazon.


More Longevity and Healthy Ageing Science Book Reviews:


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