Why We Sleep
Unlocking the power of sleep and dreams
Matthew Walker, PhD
368 pages in hardcover
Review edition: 2019-04-26
As is customary for my book reviews on The Undoctored Inner Circle site,
the read was undertaken to determine if this book (WWS) might provide health
benefits (in this case circadian) beyond what might be expected by
someone already following the latest program advice here. The reader of this
book review is presumed to be following Undoctored
or 2014+ Wheat Belly, and aware of:
In a nutshell, absolutely yes, WWS is a valuable read for the present audience,
despite its modest
and perhaps particularly valuable if you think that sleep is some
sort of vestigial habit that is largely optional for modern humans.
I made several additions to my own Sleep Tips article as a result of
reading this book.
If you have children, or run a business (or a school), this book is a must read.
If you consider yourself to be some sort of circadian warrior,
who only needs 6 (or fewer) hours per night, you are almost certainly
mistaken. Even if you are one of the 1-in-12,000 with mutant DEC2/BHLHE41 SNPs,
they may or may not actually confer tolerance to low sleep.
If you don’t plan to read the book, at least listen to Peter Attia’s
(downloadable) 6 hour interview with Matthew:
Part 1 (1:43:10),
Part 2 (2:04:31),
Part 3 (2:01:05)
What WWS Is About
It’s a comprehensive roll-up of sleep research, circa 2016 or so,
and is not restricted to Walker’s own work.
A consistent sleep regimen, that includes ample time for key phases,
is crucial. Sleep is not just one thing. It is complex, obligate,
neuro-physiologic-metabolic state. It is not negotiable, bankable,
recoverable to any great degree, nor trivially re-scheduled.
Adults, infants, children and adolescents have different (obligate) schedules.
Humans are the only species that deliberately shorts sleep for
reasons other than severe threats and pressing need to forage
— and humans are exceptionally poor at recognizing the
consequences (perhaps because the problems never really arose
prior to bright artificial light, so there was never a need
for a specific danger sense to emerge).
Poor sleep and insufficient sleep adversely and sharply shifts
almost every health marker that matters: IR/BG/A1c, leptin, ghrelin,
arterial plaque, Aβ, tau, judgement (including food choices),
microbiome, immunity (esp. killer cells & cancer risk), inflammation,
BP, memory consolidation, reaction time, multiple reproductive factors,
Speaking of cites, it’s clear that all medical and nutritional
trials and studies, animal or human, need to account for subject sleep,
and almost none do.
Although it was late-breaking news during authoring, the book
managed to include a couple of pages on the role of the
As conjectured in that 2015 thread, this brain lymph system acts
as a sewer system for brain waste products. What’s new information in
this book is that it does so mainly during sleep, and mainly during
deep NREM sleep (the sleep highly disrupted in AD). It further
turns out that Beta amyloid and tau are two of the things cleaned
out when this system is functioning properly. There may be a role for
tDCS here, still unclear.
The book goes through all the benefits and hazards, one by one, with cites.
This all appears to lead Walker to posit that sleep might be the most
important factor in modern health (and he can be forgiven for that,
because the book shows only minor awareness of emergent wisdom on diet
generally and microbiome). I’ve been lately toying with a pie chart of
core/foundational matter in modern health. There are 7 slices so far in the
pie chart. None is the single most important. All are mandatory.
One is “ancestral sleep”.
There is extensive discussion on caffeine and alcohol, and many
consumers thereof aren’t going to be happy about it.
I was a bit surprised to find that how I’ve evolved
my own consumption aligned with his advocacies.
There is extended, lawyer-reviewed, heavily cited, obviously pulled-punch
discussion of current pharmaceutical sleep aids, why they don’t work,
and why they are instead a huge mistake.
ADHD/ASD meds are also discussed (and disparaged).
There is discussion of various specific sleep ailments, such as narcolepsy,
and the current state of treatments for them.
There is extended discussion of cultural issues that aggravate circadian
disruption, many straightforward to fix, if the
“entrenched pomposity” of sector leadership can be deflated.
The appalling tale is presented, describing how the lethally horrific circadian
disruption of medical residency came to be. That section picks up on another recent
Dr. Davis theme
by leading off with:
||“If you are about to receive
medical treatment at a hospital, you’d be well
advised to ask the doctor: “How much sleep have
you had in the past twenty-four hours?” The
doctor’s response will determine, to a statistically
provable degree, whether the treatment you receive will
result in a serious medical error, or even death.”
What Wasn’t Found
There is very little discussion of diet, with one mention of avoiding
excess carbohydrates (over 70% of calories, yikes). There is a caution
on avoiding caloric restriction, due to adverse sleep effect. But there is
no discussion on any sleep risks that might or might not be associated
with intermittent fasting (daily vs. multi-day) or ketosis (sub-seasonal
The book does make clear that a major adverse effect of sleep deficiency
is dysbiosis (although not by that term). Immune function can get wrecked
(part of the cancer connection). When lab animals die as a result of sleep
deprivation, the actual cause of death appears to be septicemia from
unchecked ordinary gut microbes. But the book has no awareness of our current
pandemic human dysbiosis, so no leads on rectifying it.
The book’s coverage of the bright and blue night at night hazard
has a lot of overlap with other discussions of this
my own), but “ipRGC” curiously does not appear in WWS
(although SCN does), and the vilification of LED lighting in the book
is far too broad (cheap white-light LEDs are indeed a problem, but
are the solution, given that the only other option under current
energy policy would be CFL, which is
Many people must awaken at a no-later-than time each work day.
I was expecting the book to have some discussion of how to
navigate that challenge. For example, how about using a wearable
that purports to track sleep phases, and can serve as an alarm to
wake you at the optimum phase moment pre-deadline (and yes, this
might require going to bed earlier). Anyway, not found (but then,
perhaps the needed tech didn’t exist in 2016, and may not yet).
Bob Niland [disclosures]