In an era where sleep is rubbished as a “waste of time” or “inefficient”—it’s time to look at the evidence from an authority on the topic.
Matthew Walker is a Professor of Neuroscience at UC Berkeley and former Professor of Psychiatry at Harvard Medical School.
His book, Why We Sleep, is an ode to shut-eye and why getting your nightly 8+ hours (plus nap) is crucial to living your highest purpose.
You might be familiar with these scenarios:
“I pulled an all-nighter!”
— Newbie lawyer (which might be me back in the day)
“My team worked 30 hours straight to finish these pleadings.”
— Partner-who-shall-not-be-named
Back in the 90s, a popular turn of phrase (at least in my books) was the Kit-Kat advertisement, “Have a break, have a Kit-Kat!”
These days, both junk food and breaks have fallen out of popularity. The first one is great (subject to “health food” fads), the second one—terrible.
Some circles see sleep as “a waste of time”. It brings to mind the modern, go-getter entrepreneur, “thriving” on four hours of sleep a night. I’ve seen blog articles on how you can “get more efficient” by sleeping 30 minutes and working hour-and-a-half cycles over a 24-hour period. Completely bonkers.
Messing around with your shut-eye can kill. In 2013, a 21-year-old banking intern in London died after working 72 hours straight. In Japan, a 31-year old journalist died from heart failure after working 159 hours of overtime. Earlier this year, Japan introduced new laws to cap overtime and address karoshi (death from overwork). However, there are doubts that these laws will work, given stories of companies creating fake work logs for labour inspectors.
Ok, but that’s not me!
How about the rest of us, who tend to gravitate between the 5 to 7-hour mark? This is where Why We Sleep comes in as a crucial book for our times.
Turns out, we’re still doing ourselves a huge disservice. The following graphs will tell you that anywhere under 8 hours of sleep means you’re underperforming in all areas of life. This includes life or death situations.
“Chronic lack of sleep is associated with increased sports injuries in adolescent athletes”: M.D. Milewski et al. (2014) Journal of Paediatric Orthopaedics 34(2), 129-33.
Sadly, the chronically sleep-deprived don’t realise that they are quite literally driving off a cliff:
“With chronic sleep restriction over months or years, an individual will actually acclimate to their impaired performance, lower alertness, and reduced energy levels. That low-level exhaustion becomes their accepted norm, or baseline.”
— Why We Sleep, page 137
You can’t fight your biology
Sleep is universal in all living animals and has an ancient evolutionary origin. Even “very primitive worms enjoy periods of slumber”.
Except for an extremely small group of people in this world who can get by with less than 5 hours of sleep with minimal impairment (which Walker assures is NOT likely to be you)—Walker provides compelling scientific evidence for why 8+ hours of sleep is non-negotiable.
“Sixty years of scientific research prevent me from accepting anyone who tells me that he or she can ‘get by on just four or five hours of sleep a night just fine.’”
— Why We Sleep, page 137
Ok, sleep is important. In fact, we know this innately.
So let’s step through some of the fun facts.
1. Want to get 40% smarter?
During the semester (and especially this time of year), law students will be cutting down on their sleep to prepare for final exams. And that’s a serious issue.
For the unaware, sleep feels like a luxury. I recall many conversations with fellow students who admitted that they did an “all-nighter to cram” or slept less than five hours a night. The bad news is, you’re putting yourself at a significant disadvantage.
In a 2006 study, Walker took a large group of university students and split them into two groups—the first had a full night of sleep, while the second stayed up all night. The next day, they were asked to remember a list of facts (while in an MRI machine). Then, both groups had two full nights of recovery sleep.
When Walker and his team tested their memories later on, the difference between the two groups was stark:
“When we compared the effectiveness of learning between the two groups, the result was clear: there was a 40 percent deficit in the ability of the sleep-deprived group to cram new facts into the brain (i.e. to make new memories), relative to the group that obtained a full night of sleep. To put that in context, it would be the difference between acing an exam and failing it miserably!”
— Why We Sleep, page 137
This study also debunks the myth that you can pay off your “sleep debt” later:
“… if you don’t sleep the very first night after learning, you lose the chance to consolidate those memories, even if you get lots of ‘catch-up’ sleep thereafter. In terms of memory, then, sleep is not like the bank. You cannot accumulate a debt and hope to pay it off at a later point in time. Sleep for memory consolidation is an all-or-nothing event.”
— Why We Sleep, page 137
Want to ace your exams? Don’t cut back on your sleep.
2. Get more creative, solve more problems
Most of us are aware that solutions to problems always make more sense in the morning. It’s thanks to REM sleep, which allows us to “spark new creative insights as novel links are forged between unrelated pieces of information”. When you cut down on sleep, you also lose out on important REM sleep that happens towards the tail-end of your sleep cycles.
It’s amazing that the only thing that differentiates us from machines (if you’re at all concerned)—creativity grounded in sleep—is something that many organisations ignore.
Even worse, when organisations (including law firms) demand that their sleep-deprived employees get more creative in solving problems. We love counterproductivity.
3. Physical health
We obsess all day about healthy eating (*cue* yucky green juice) and work ourselves into a frenzy with F45 / HIIT exercise. But we hardly think about our sleep. What a bizarre pizza we are!
Walker notes that diseases like dementia, cancer, and diabetes can be linked to insufficient sleep, which forces the sympathetic nervous system into overdrive. Sleep builds up our immune system and suppresses our ad-hoc eating. Sleep is the foundation for exercise and healthy eating, not the other way around.
On this note, it’s not only the Mediterranean diet that prolongs your life. The siesta, long decried as a form of laziness, has serious impacts on public health spending. Researchers from Harvard University’s School of Public Health compared 23,000 Greek adults over a six-year period where some abandoned the siesta practice:
“As with countless Greek tragedies, the end result was heartbreaking, but here in the most serious, literal way. None of the individuals had a history of coronary heart disease or stroke at the start of the study, indicating the absence of cardiovascular ill health. However, those that abandoned regular siestas went on to suffer a 37 percent increased risk of death from heart disease across the six-year period, relative to those who maintained regular daytime naps. The effect was especially strong in workingmen, where the ensuing mortality risk of not napping increased by well over 60 percent.”
— Why We Sleep, page 137
It turns out that biphasic sleep (i.e. 8+ hours plus an afternoon nap) is “a prescription written long ago in our ancestral genetic code”. I look forward to the day when enlightened organisations put up that hammock at work.
4. Mental health
A result of excessive working hours, covered in “Let’s talk about busywork”, is that something has to give. Most of the time, that’s sleep.
“It is no coincidence that countries where sleep time has declined most dramatically over the past century, such as the US, the UK, Japan, and South Korea, and several in western Europe, are also those suffering the greatest increase in rates of … physical diseases and mental disorders.”
— Why We Sleep, page 137
We can’t talk about mental health without talking about sleep. Unless we change the number of hours we work (and hence the amount of sleep that we get)—chit-chatting about mental health is a Band-Aid solution.
5. Good sleep is good business
Want honest, creative, amazing and profitable employees? Don’t let them loose when sleep-deprived.
“[The underlying drivers of KPIs in business are determined by numerous employee traits including] creativity, intelligence, motivation, effort, efficiency, effectiveness when working in groups, as well as emotional stability, sociability, and honesty. All of these are systematically dismantled by insufficient sleep.”
— Why We Sleep, page 137
And something we lawyers always knew, but decided not to do:
“Under-slept employees are not… going to drive your business forward with productive innovation. Like a group of people riding stationary exercise bikes, everyone looks like they are peddling, but the scenery never changes. … when you are not getting enough sleep, you work less productively and thus need to work longer to accomplish a goal.”
— Why We Sleep, page 137
It’s no surprise then that a lot of legal advice reads like gibberish. Or when we lawyers produce 20+ folders of “relevant documents” which mostly deserve to live in the trash can.
6. Caffeine won’t save you (gah!)
Here at Legal Brew, I love a great cup of coffee. But the sad part is that caffeine doesn’t make up for a lack of sleep.
In one fun NASA experiment, researchers put a bunch of spiders on stuff and let them weave their webs. You will never look at coffee the same way again:
Sleep tips
Read Why We Sleep. It will change the way you think about your sleep. But if you don’t, here are some tips from Walker on getting a decent shut-eye:
- Reduce caffeine and alcohol intake (both interfere with proper sleep).
- Remove screen technology from the bedroom and have a cool bedroom (temperature-wise, not like interior design).
- Establish a regular bedtime and wake-up time, even on weekends.
- Go to bed only when sleepy and avoid sleeping on the couch early/mid-evenings.
- Never lie awake in bed for a significant time period: rather, get out of bed and do something quiet and relaxing until the urge to sleep returns.
- Avoid daytime napping if you are having difficulty sleeping at night.
- Reduce anxiety provoking thoughts and worries by learning to mentally decelerate before bed.
- Remove visible clock-faces from view in the bedroom, preventing clock-watching anxiety at night.
Further reading:
- ABC Big Ideas podcast, “The Science of Sleep” (3 July 2019) on sleep-deprived fruit flies and other curiosities.
- Andrew Anthony, “The island of long life” (1 June 2013, The Guardian) on ageless 90+ year-olds on the Greek island of Ikaria.