You hear of an amazing breakthrough in the overall treatment of your health problems. This breakthrough enables you to live longer, obtain a greater memory and makes you more creative. In addition, you find it easier to maintain your ideal weight, and you feel less inclined to give in to your unhealthy cravings. Furthermore, it shields you from cancer and dementia, colds and the flu, heart attacks and stroke, and even diabetes. You’ll be happier and more well-adjusted. And it’s something your body does naturally.

Who wouldn’t be interested?

Unfortunately, surprisingly many. You’d have guessed by now that we’re referring to sleep. Two thirds of adults in developed nations do not receive the stipulated eight hours of sleep each night, and it has been causing a host of problems that are costly both to the quality of life for the individual and the economic health of the societies they reside in.

Health problems ranging from deficient immune systems, diabetes, cardiovascular disease, and unwanted weight gain, to depression, anxiety, and suicidal thoughts, are all exacerbated by lack of sleep. The problem is serious enough for the world health organisation to label sleep loss as an epidemic.   

All species on earth sleep in some way or other. This suggests that sleep evolved along with the earliest life on the planet and hence brings with it benefits that, on balance, outweigh whatever costs it might also inflict to organisms (it would not have survived natural selection otherwise). Therefore, even though there is much about sleep that remains to be understood, recent research has uncovered just how vital sleep is to healthy human functioning.  

Matthew Walker, professor of neuroscience and psychology at the University of California, devoted twenty years of his research career on the phenomena of sleep. His book, Why We Sleep 1st edition, is a lay-friendly exposition of his research and will constitute the source material for this article.

[October 2021 Update: Dr. Walker has since published a response to critics about some of his claims in his book and has updated any information that has been superseded by new research on sleep. His post can be found here. He has also just published a second edition with the updated information]

No facet of the human body is spared the crippling, noxious harm of sleep loss. We are, as you will see, socially, organizationally, economically, physically, behaviourally, nutritionally, linguistically, cognitively, and emotionally dependent upon sleep

Walker

So, what are the biological signals that activate and sustain human sleep? The first is our circadian rhythm. It’s an internal twenty-four-hour clock in the brain that tracks the day and night rhythm of the planet and makes you feel tired and sleepy or alert and active at the appropriate times. The second is sleep pressure, i.e., facilitated by a chemical called adenosine that builds the longer we’re awake, such that we feel progressively sleepier towards the evenings.

Both signals work separately but also contemporaneously to create the natural cycles of sleep we’ve been experiencing since birth (stabilized from about four years of age). Our circadian rhythm signals the body to drop its core temperature around bedtime and raises it again when it’s time to wake up, much like a metronome, irrespective of whether we’re actually sleeping. It is also important to note that circadian rhythm timings differ among people.    

There is, therefore, in fact, a genetically determined explanation for morning larks and night owls, who feel wakefulness and sleepiness at different times in the day or night and hence function most effectively at those periods of time. Unfortunately, society is, for the most part, structured to favour the morning lark.

Jet lag is another consideration for modern working people since our sleep signals did not evolve to track us as we travel over thousands of miles across time zones in several hours. Our suprachiasmatic nucleus (SN), the region of the brain responsible for controlling our circadian rhythms, can readjust at about an hour a day. This means that if you traveled somewhere eight hours ahead or behind where you left, you’d take around eight days to fully adjust to the new time zone. As we know, however, our SNs rarely get the opportunity to do so, since we’d likely be jet-setting somewhere off soon to fulfill other work obligations.  

We cycle between two kinds of sleep, non-REM and REM sleep. Both of them perform different but essential functions. The first half of our nightly sleep comprises ninety-minute cycles of NREM sleep with a little REM sleep. This serves to remove obsolete neural connections in the brain. The second half of our sleep comprises much more REM sleep. This serves to strengthen new and important neural connections. This back and forth between NREM and REM likely serves to remodel and update neural circuits given finite storage in the brain. In other words, this process deletes relatively useless information to accommodate new information that the brain considers salient.  

The fact that our sleep functions are split into half across the night –  tracked with our circadian rhythms – means that we lose more NREM or REM sleep relative to our overall sleep loss based on when and how long we sleep. To illustrate, if you started sleeping from eleven, you would need to wake up at seven to achieve eight hours of sleep. If however, you woke up at five, you’d lose only twenty five percent of your overall sleep, but you’d also lose up to ninety percent of your REM sleep. Conversely, if you slept late at two and woke up at eight, you’d lose much more of your NREM sleep.   

When it comes to sleep, there is no such thing as burning the candle at both ends—or even at one end—and getting away with it

Walker

Brainwave activity characteristic of NREM sleep resembles a football stadium full of fans chanting and falling silent in perfect unity. In such a state, the brain is, in fact, highly active. In REM sleep, emotions, motivations, and memories are allowed to enter the cortex, and dreaming, i.e., the theatre of the bizarre, commences. REM sleep attempts to integrate your waking experience with the reflective NREM process to create ever more accurate models of how the world works, allowing us to achieve new insights and abilities. If you’ve ever experienced the magic of sleep in relation to solidifying some skill you’ve been learning, this is the reason.

REM sleep helps with emotional processing, and hence, gives us the tools to navigate our social lives. It also supercharges creativity because the integration of our novel experiences with the rest of our life story allows for new associations to be formed. It is no coincidence, therefore, that it’s in the second and third trimesters of human development, when the brain is being constructed piece by piece, that REM sleep dominates, and issues in development caused by problems with sustained REM sleep are linked to disorders across the autism spectrum. Hence, mothers who drink heavily during pregnancy inhibit the REM sleep of their unborn child and put them at greater risk of the above neuropsychiatric illnesses. 

In recent centuries, adults in developed nations have been sleeping in a monophasic pattern, that is, in one ‘sitting’ at night. But vestiges of our bi-phasic past can nevertheless be found in cultures that are unaffected by electricity. In hunter-gatherer tribes across Africa, adults would also take a nap in the afternoon. Other tribes would sleep in bi-phasic pattern in the Summer and then switch to the monophasic pattern during the cooler months.

Societies that until recently observed siestas, like some of those in Greece, had public health studies of over twenty thousand adults who lived across the change demonstrating that the progressive abandonment of siestas came with a thirty seven percent increase in heart disease diagnoses. 

Teenagers are at a vital point in the lives where sleep plays the crucial function of pruning the connections created by REM sleep. Hence, deep NREM sleep helps teenagers improve their visual and spatial perceptions as well as their rational and decision-making skills, which will pay dividends for them over their lifetimes. They also need more sleep than adults. 

Unfortunately, while teenagers’ circadian rhythms push forward, from nine to about midnight, they are still required to wake up early in the morning for school. But they’re just not wired to sleep at nine or ten. It would be like asking you, assuming you’re an adult, to sleep at seven. This mismatch between their sleep and wake times has caused significant problems, some of them chronic, for our young. More on this later.

Why one might ask, would there be a biologically determined push forward of the circadian rhythms of teenagers and adolescents? On an evolutionary view, the push forward could be been designed to give young people independence to separate themselves, as a group, from parental guidance, so that they can learn (or beta test) how to successfully navigate their own social lives and prepare for their eventual separation from their parents. Though hypothetical, the collective experience of parents having to deal with their impossibly rebellious teenage children’s after-hours habits seems to corroborate this.

Because it is hard to do a self-diagnosis on the quality of our sleep, many, especially those in their older years, fail to make the connection between their deteriorating health and cognitive abilities with their deteriorated sleep. Regardless, the connection between sleep or NREM sleep specifically, and cognitive abilities like memory strength is also found among chimpanzees, bonobos and orangutans, even cats, rats, and insects.

Common things that we ingest, like caffeine, have an adverse effect on the quality of our sleep too. Caffeine takes about thirty minutes to peak in circulation after ingestion. And it has an average half-life of five to seven hours, conditioned on how effectively the enzyme in your liver is able to degrade it, which differs from person to person. This means that if you had coffee around dinner time, there’d still be fifty percent of caffeine in your system by the time you retire to bed. Not just coffee, but decaffeinated coffee, energy drinks, dark chocolate, and ice cream contain caffeine.  

Chronic sleep deprivation among working adults in industrialized nations, along with their need to reup on caffeine, has led to vehicle accidents more prevalent and dangerous than drunk and drugged driving combined. The latter often get into accidents because the drivers were late to break or swerve. In the case of a sleep deprived driver, there is no reaction at all: they do not break or attempt to swerve to avoid collisions because they are asleep. Hence the collision is often much worse and the fallout more devastating.

Other kinds of studies on individuals suffering from psychiatric conditions like bipolar disorder have shown that one night of sleep deprivation increased manic episodes among the majority of those under study. Thankfully, cognitive behavioural therapy for insomnia has shown to help remission rates, not only of those suffering from bipolar disorder but for all kinds of conditions including depression, anxiety, and suicidal thoughts. 

The best bridge between despair and hope is a good night’s sleep

E. Joseph Cossman

Sleep also allows for the removing of metabolic contaminants accumulated during waking hours. The glial cells in the brain shrink at night, allowing for our cerebrospinal fluid to wash out those contaminants. Some of those contaminants, like amyloid protein, the protein tau, as well as certain stress molecules, are linked to Alzheimer’s disease. It follows that getting too little sleep across your adult lifespan will increase your chances of developing the disease. 

Parenthetically, and unscientifically, I have always found it curious that Margaret Thatcher and Ronald Reagan—two heads of state that were very vocal, if not proud, about sleeping only four to five hours a night—both went on to develop the ruthless disease.

Walker

Going back to the link between sleep and heart disease, a long-term study with a sample size of half a million people of varied races and genders found a connection between shorter sleep and an increasing risk of dying from coronary heart disease. Another ‘experiment’ done simply by reviewing the daily hospital records of places that are affected by daylight savings, i.e., the loss of one hour of sleep, featured a marked rise in heart attacks and vehicle accidents the following day. 

REM sleep helps to sooth emotionally traumatic experiences and offers sufferers some resolution over time. When individuals suffering from PTSD were treated with the drug prazosin which gave them better quality REM sleep, the frequency of their nightmarish episodes decreased. 

It is estimated that across four large US companies, lack of sleep costs them about fifty-four million annually. At the national level, a RAND Corporation report suggests that lack of sleep costs America about four hundred and eleven billion dollars each year, with similar costs for other nations.

Sleepy employees are bad employees, they work slower, are less accurate, less motivated, less happy, and engage in more unethical behaviour. This is because the frontal lobe, which governs self-control and regulates emotional impulses, is inhibited by the lack of sleep. If the under-slept are in management, their disengagement and reduced productivity spread like viruses across the organization.

Some companies have realised the detrimental effects of lack of sleep to their bottom line and have offered free sleep courses and even changed their building lights to synchronise with the circadian rhythm of their workers so that they can release melatonin at the right times to achieve better sleep. 

Other companies test their workers’ circadian rhythms more precisely and allow those of different chronotypes, i.e., morning larks and night owls, to work at their most optimal periods. They even have pods that allow workers to sleep on the job. NASA has been doing this since the 1990s and they’ve enjoyed increases in performance and alertness among their workers. 

But if such concessions, i.e., acknowledging the importance of sleep, are made for working adults, what about our children? In America, the majority of public high schools start before eight fifteen, and some before seven twenty. This means that kids have to wake up a little after five on weekdays to get to school on time. Calibrating their circadian rhythms to ours, it would be the equivalent of being made to wake up at three fifteen in the morning for years on end. What do you think this would do to your physical and mental health?  

It doesn’t help that teenagers are at the greatest risk, by virtue of their age, for developing chronic mental illnesses.

Read of any attempts to break sleep-deprivation world records throughout early history, and you will discover this same universal signature of emotional instability and psychosis of one sort or another. It is the lack of REM sleep—that critical stage occurring in the final hours of sleep that we strip from our children and teenagers by way of early school start times—that creates the difference between a stable and unstable mental state

Walker

Conversely, getting the adequate sleep that our kids are evolutionarily programmed to receive brings a host of benefits. The more children slept, the more intellectually gifted they tested. A study of five thousand Japanese students demonstrates the aforementioned effects with just forty or fifty minutes of additional sleep. Schools in America, like those in Edina, Minnesota, which changed their start times from seven twenty-five to eight thirty, saw a net SAT score improvement of two hundred and twelve points among their students. Studies in other counties reveal similar results.

The last thing any educational system wants is to create a generation of disadvantaged students. Yet early school start times contribute to such a host of detrimental factors that they must be tackled if we are to improve the well-being and life prospects of our children. Apart from improvements in academic performance, delaying school start times decreases substance and alcohol use, reduces symptoms of ADHD, and lowers teenage crime (and its attendant costs to society) because they return home closer to when their working parents return as well and aren’t left unsupervised throughout the afternoon.   

Of course, there are numerous pragmatic reasons for early school start times, such as easing traffic congestion, the decisions of bus unions, and so on. On balance, however, the positive impact of delayed school start times outweighs drawbacks to the other trade-offs under consideration, at least in the American context. 

Data aggregated over the past century from more than 750,000 schoolchildren aged five to eighteen reveal that they are sleeping two hours fewer per night than their counterparts were a hundred years ago.

Until policies change to reflect what humans of all ages naturally need from sleep, what can we do to improve our sleep? Some have already been mentioned in my previous article on sleep, but are worth repeating here.

The first thing you can do is a simple sleep assessment. If after waking in the morning you have little problem falling asleep again at ten or eleven, you are sleep deprived. If you cannot function normally without caffeine before noon, you are sleep deprived. If you feel sleepy and fatigued even after a full night’s sleep, you might be suffering from an undiagnosed sleep disorder. Consider getting referred to a sleep specialist and remember not to resort to sleeping pills as the first solution. 

Consider these first factors: electric and LED lights, temperature, caffeine, alcohol, and working hours. First, reduce exposure to blue light in the evenings, i.e., after the sun has set. A normally lit living room can have a fifty percent suppression of melatonin in the brain. Get black-out curtains, calibrate your devices to suppress blue light in the evenings, and even consider wearing blue light blocking glasses.

The most effective temperature for sleep is around eighteen point three degrees Celsius, assuming warm bedding and night clothes are used. Hot baths before bed invite dilated blood vessels near the surface of the skin, which helps radiate out inner heat, and help you fall asleep faster and deeper.  

Alcohol, like sleeping pills, may seem to help you with sleep. But they are in fact sedatives; they stop your brain cells from firing and produce lower quality sleep (i.e., sleep that lacks the largest and deepest brainwave activities) than if you fell asleep while not under their influence.

Cognitive behavioural therapy for insomnia remains the most effective first line of treatment. Patients work with therapists to break bad sleep habits and create good ones. Some of these include establishing a regular sleep and wake time, even on weekends, having a cool room, reducing use of screens from sunset onward, only going to bed when sleepy, never lying awake on the bed for long periods of time, avoiding daytime napping if it affects night-time sleep, removing the view of clocks, engaging in regular exercise but not close to sleep time, not going to bed too full or too hungry, avoiding high carb diets, sugars, caffeine and alcohol, and so on. 

What follows is curated advice for better sleep from sources outside Matthew Walker’s book.

• Get a polysomnogram done to diagnose sleep disorders if you suspect that you have one.
• Use apps, wearables, and other kinds of monitors that have been proliferating in the tech space to gauge your sleep health.
• A less technological approach would be to keep a sleep journal to document and test factors that facilitate a good night’s sleep.
• Invest in a white noise machine or ear plugs if sound pollution is a problem.
• Replace alarm clocks with progressive lighting that produces melatonin in the morning along with softer sounds. 
• Engage in relaxing activities before bed, so no competitive gaming, strenuous work, or action movies. Gentle stretching helps.  
• Get sunlight exposure in the mornings, and spend more time outside when there is daylight.
• When indoors, rely on natural light as much as possible.
• Consider investing in a light therapy box if the winter months are especially dark where you live.
• Try deep breathing exercises before sleeping. Lie down, close your eyes, and breathe from your belly, in from your nose and out through your mouth. Count your exhales and focus on relaxing and not trying to sleep.
• Do a body scan while in bed: place attention on different parts of your body and consciously tell that part to relax. Detailed procedures for body scanning can be found online.
• Experiment with mattress firmness and pillow support. Your bed should be great to sleep in and not cause aches and pains in the morning.
• Keep the bedroom only for sleeping, not working, watching, or anything else, maybe apart from sex. Your brain will associate the environment for sleeping only and you’ll sleep faster.
• If you wake up in the middle of sleep, don’t be stressed about it. Engage in breathing exercises and relax.
• Write down whatever is worrying you and commit to worrying about it when you wake up.
• Melatonin supplements might help.
• Don’t drink liquids before bed so you won’t have to wake up in the middle of the night to use the toilet.
• Invest in dimmable lights so that if you have to move around in the middle of the night you won’t stumble or hurt yourself.  
• If you get hungry at night, consume whole-grain cereals, milk, yogurt, chamomile tea, almonds, a kiwi, tart cherry juice, fatty fish, walnuts, passionflower tea, white rice, or a banana.
• If you sleep on your side, hug a bolster. The pillow would have to have more support for your neck also if you sleep on your side.
• Your mattress may contain irritants, so seal them, clean them, and get new ones every five years or so.
• No pets in bed.
• Try aromatherapy.
• Wear socks to help train the temperature out from your extremities.

For methods of falling asleep, there’s (1) the military method, (2) the 4-7-8- breathing method, (3) progressive muscle relaxation, (4) tell yourself to stay awake, and (5) visualize a calm place. 

• Military Method

Relax face and insides of the face; drop shoulders and hands; exhale to relax chest; relax legs, thighs, and calves; clear your mind for ten seconds by imagining relaxing scenery; say don’t think over and over again in your mind.

• 4-7-8 Breathing Method

Exhale through your mouth with a whooshing sound; inhale silently though nose in four seconds; then pause for seven seconds; exhale for eight seconds through the mouth; repeat. 

• Progressive Muscle Relaxation

Tighten forehead muscles for five seconds, relax them for ten; do the same for mouth; then eyes; then neck; then the rest of your body until you fall asleep.

• Tell yourself to stay awake

If you have sleep performance anxiety, telling yourself to stay awake while in bed helps.

• Visualise a calm place

It’s exactly what it sounds like. Designed to help you let go of your thoughts, worries, and concerns. 

The above techniques take several weeks of practice before they’re effective, so be patient and work at it! Share this article if you think it’ll help someone. For more information, read Matthew Walker’s book.