why we sleep and what you need to do about it

Reading time: 5 mins

“Sleep that knits up the ravelled sleave of care. The death of each day’s life, sore labor’s bath. Balm of hurt minds, great nature’s second course. Chief nourisher in life’s feast.” William Shakespeare

Sleep deprivation has some crazy side effects 

A paradox of modern life is that despite clear and unequivocal scientific evidence as to why sleep is so important for our health and effectiveness we still continue to deprioritise it.  As an elite combat leader I pretty much spent my entire 20’s sleep deprived; either whilst deployed on military operations, training exercises or oftentimes by living a little too closely to the ‘work hard play hard’ mantra.  So its no surprise that after reading Matthew Walkers “why we sleep” a couple of years back I could only wonder at the damage I must have done to myself during the ‘invincible’ years.


Infact, I have first hand experience of the deleterious effects that sleep deprivation can have on people’s ability to concentrate, make effective decisions and manage their emotions.  The elite levels of training I received were designed to make me as effective a leader and decision maker as possible whilst constantly operating in austere conditions and under significant levels of stress and fatigue.  However, looking back on it now I can safely say that had I spent the rest of my life operating under such conditions then I would surely have suffered significant impairment to my future quality of life.


I’m going to capture below some of the key lessons and advice around developing good sleep hygiene so that we can learn to implement more effective sleep habits and routines into our daily lives.  As mentioned earlier the book ‘Why we sleep’ by Matthew Walker is generally considered to be the most comprehensive book on the subject.  It is also written and designed with the lay person in mind (me) and is therefore readily accessible and full of anecdotes whilst delivering some sobering warnings of what will happen to us if we continue to ignore the problem.


Sleeping Cat

Everyday vices – caffeine, jet lag and melatonin

The shorter your sleep the shorter your life span.  This is the overriding point that is made again and again in ‘Why we sleep’.  More important than regular exercise and balanced nutrition sleep is the single most effective thing we can do to reset our brain and body health each day.   Your circadian rhythm is one of two factors determining wake and sleep. Melatonin is a naturally produced hormone that helps regulate the timing of when sleep occurs by signalling darkness throughout the organism, however it has little influence on the generation of sleep itself.   So your actual sleep pressure, the drowsiness you feel is caused by a build up of the chemical adenosine in your brain, along with melatonin release this is the second factor affecting sleepiness.  So for those of us who enjoy regular cups of coffee throughout the day caffeine works by blocking the receptors inside the brain that adenosine effects (after around 30 mins).  This is great for short term productivity but as Walker points out the adenosine continues to build up outside the receptors so that when you finally finish your coffee for the day or week and the caffeine wears off your receptors are flooded with the back log of adenosine causing you to experience a fatigue crash.  I’m sure this is a familiar experience for all of us.  I’m not saying that some caffeine, used judiciously, may not actually have beneficial effects however most of us are consuming way more than is necessary on a daily basis and when compounded over time this starts to have a systemic effect.  I have consciously switched to de-caffeinated coffee over the last few years (yes it still has some caffeine) and only have one or two cups in the morning as part of my routine.  At some point I will try and go coffee free – although there is something reassuring about the warmth and smell of a good brew in the mornings and I need to find a good alternative to do.

Why should you sleep?


Walker lays out the evidence and scientific research to deconstruct and itemise the numerous benefits of good quality sleep.  Of the many advantages conferred by sleep on the brain, that of memory is especially impressive, and particularly well understood. Sleep has proven itself time and again as a memory aid: both before learning, to prepare your brain for initially making new memories, and after learning, to cement those memories and prevent forgetting.   Drilling down further, in what spanned almost a decade of research, Walker identified the type of sleep responsible for the overnight motor-skill enhancement, carrying with it both societal and medical lessons. The increases in speed and accuracy, underpinned by efficient automaticity, were directly related to the amount of stage 2 NREM, especially in the last two hours of an eight-hour night of sleep.


Obtain anything less than eight hours of sleep a night, and especially less than six hours a night, and the following happens: time to physical exhaustion drops by 10 to 30 percent, and aerobic output is significantly reduced. Similar impairments are observed in limb extension force and vertical jump height, together with decreases in peak and sustained muscle strength.  Add to this marked impairments in cardiovascular, metabolic, and respiratory capabilities that hamper an under slept body, including faster rates of lactic acid build up, reductions in blood oxygen saturation, and converse increases in blood carbon dioxide, due in part to a reduction in the amount of air that the lungs can expire. Even the ability of the body to cool itself during physical exertion through sweating - a critical part of peak performance - is impaired by sleep loss.  As someone who is dedicated to attaining peak physical performance these findings are concerning for me and they really challenge the myth of the 4 hour a night super executive who gets it all in and is still operating at peak.  It simply isn’t true and I suspect we all suffer from this distorted comparison as society as a whole is functioning in a sleep deprivation bubble.  


Let’s drill down further and understand some of these negative consequences of sleep deprivation before we consider what good sleep hygiene looks like.  Walker claims that chronic and continued lack of healthy sleep is linked to devastating effects on the brain; there are numerous neurological and psychiatric conditions (e.g., Alzheimer’s disease, anxiety, depression, bipolar disorder, suicide, stroke, and chronic pain), that act on every physiological system of the body, further contributing to countless disorders and disease (e.g., cancer, diabetes, heart attacks, infertility, weight gain, obesity, and immune deficiency).


No facet of the human body is spared the crippling, noxious harm of sleep loss.

Pay Attention


One brain function that buckles under even the smallest dose of sleep deprivation is concentration. The deadly societal consequences of these concentration failures play out most obviously and fatally in the form of drowsy driving. Every hour, someone dies in a traffic accident in the US due to a fatigue-related error.  Not only this, but Walker finds that participants who are sleep deprived consistently underestimate the degree to which their performance is reduced.  The simple truth is that humans need more than seven hours of sleep each night to maintain cognitive performance. A startling fact that I read was that after ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours.  Consider that for a moment the next time someone brags about how they are ‘getting after it’ on only 5 or 6 hours of regular sleep a night.  The fact is that it is an illusion; just because you get up at 0430 does not mean you are getting after it – you need to fix your personal process first so that you can optimise the benefits of early starts.  Look, I am a massive fan of the Jocko Willink /David Goggins “no excuses” philosophy of embracing the suck, focussing on the positives and driving on through no matter what.  My fear is that it encourages people to overlook the crucial investment in personal process and proper sleep that is necessary for sustainable high performance.


Walker explains also that three full nights of recovery sleep (i.e., more nights than a weekend) are still insufficient to restore performance back to normal levels after a week of short sleeping. Finally, the human mind cannot accurately sense how sleep-deprived it is when sleep-deprived.  These messages are hard to take if like me you are a willing participant in the ‘always on’ culture that pre-dominates in society.   We tell ourselves lies and myths around sleep when in reality there is no shortcut.


One point I will make here and its one that Walker also confirms in his book is around the myth of those people who claim that they only need 6 hours of sleep to function effectively.  As Walker explains “We have, however, discovered a very rare collection of individuals who appear to be able to survive on six hours of sleep, and show minimal impairment—a sleepless elite, as it were. Give them hours and hours of sleep opportunity in the laboratory, with no alarms or wake-up calls, and still they naturally sleep this short amount and no more. Part of the explanation appears to lie in their genetics, specifically a sub-variant of a gene called BHLHE41”.   However we are talking about less than 0.1% of the general population who can actually operate sustainably on only 6 hours of sleep a night.  I should know because I happen to live with one; my partner cannot sleep more than six hours a night regardless of whether it is a weekday or weekend, alarm or no alarm and frankly I’m a little envious of her secret superpower.  Jocko Willink admits to having the same condition which explains why he finds it easy to wake up at 0430 yet the mistake is in encouraging others do so if it means they get less than 7-8 hours sleep a night.  By all means wake up at 0430 however for the average joe out there, myself included, this would mean an 8.30-9pm bed time every night…and this is where, often we try to shortcut the system.

What’s stopping you from sleeping?

Beyond longer commute times and sleep procrastination caused by late-evening television and digital entertainment - both of which are not unimportant in their top-and-tail snipping of our sleep time - five key factors have powerfully changed how much and how well we sleep: (1) constant electric light as well as LED light, (2) regularized temperature, (3) caffeine (discussed above), (4) alcohol, and (5) a legacy of punching time cards.


Compared to reading a printed book, reading on an iPad or iPhone suppressed melatonin release by over 50 percent at night. Indeed, iPad/iPhone reading delayed the rise of melatonin by up to three hours, relative to the natural rise in these same individuals when reading a printed book.


Due to its omnipresence, solutions for limiting exposure to artificial evening light are challenging. A good start is to create lowered, dim light in the rooms where you spend your evening hours. Avoid powerful overhead lights. Mood lighting is the order of the night. Some committed individuals will even wear yellow-tinted glasses indoors in the afternoon and evening to help filter out the most harmful blue light that suppresses melatonin.  I’ve not yet progressed to this level of quackery / dedication but you get the point.


Maintaining complete darkness throughout the night is equally critical, the easiest fix for which comes from blackout curtains. Finally, you can install software on your computers, phones, and tablet devices that gradually de-saturate the harmful blue LED light as evening progresses.  I recently discovered how to turn my iPhone screen into monochrome mode with three clicks of a button – this is an astonishing attention hack that immediately reduces the allure of the quick phone check.


Turning Down the Nightcap - Alcohol


More than its artificial sedating influence, alcohol dismantles an individual’s sleep in an additional two ways.  First, alcohol fragments sleep, littering the night with brief awakenings.  Alcohol-infused sleep is therefore not continuous and, as a result, not restorative. Unfortunately, most of these nighttime awakenings go unnoticed by the sleeper since they don’t remember them.  Second, alcohol is one of the most powerful suppressors of REM sleep that we know of.  Glib advice aside, what is the recommendation when it comes to sleep and alcohol? It is hard not to sound puritanical, but the evidence is so strong regarding alcohol’s harmful effects on sleep that to do otherwise would be doing you, and the science, a disservice. Many people do enjoy a glass of wine with dinner, even an aperitif thereafter. But bear in mind it takes your liver and kidneys many hours to degrade and excrete that alcohol, even if you are an individual with fast-acting enzymes for ethanol decomposition. Nightly alcohol will disrupt your sleep, and the annoying advice of abstinence is the best, and most honest, I can offer.


Get the Nighttime Chills


Thermal environment, specifically the proximal temperature around your body and brain, is perhaps the most underappreciated factor determining the ease with which you will fall asleep tonight, and the quality of sleep you will obtain. Ambient room temperature, bedding, and nightclothes dictate the thermal envelope that wraps around your body at night.  A bedroom temperature of around 65 degrees Fahrenheit (18.3°C) is ideal for the sleep of most people, assuming standard bedding and clothing.  Knowingly or not, you have probably used this proven temperature manipulation to help your own sleep. A luxury for many is to draw a hot bath in the evening and soak the body before bedtime. We feel it helps us fall asleep more quickly, which it can, but for the opposite reason most people imagine. You do not fall asleep faster because you are toasty and warm to the core. Instead, the hot bath invites blood to the surface of your skin, giving you that flushed appearance. When you get out of the bath, those dilated blood vessels on the surface quickly help radiate out inner heat, and your core body temperature plummets. Consequently, you fall asleep more quickly because your core is colder. Hot baths prior to bed can also induce 10 to 15 percent more deep NREM sleep in healthy adults.

Twelve Tips for Healthy Sleep


So this has been a whistle stop tour through some of the key talking points and issues around our sleep and why we need more of it.  I would highly encourage people to read Matthew Walkers seminal book on “why we sleep” as he explores in much greater detail here than I have why good sleep helps us with and how we can return to a more evolutionarily compatible sleep routine to optimise our health.  To finish I thought I would capture 12 tips that we can all apply now for more healthy sleep:


  1. Stick to a sleep schedule

  2. Exercise is great, but not too late in the day. Try to exercise at least thirty to sixty minutes on most days but not later than two to three hours before your bedtime.

  3. Avoid caffeine and nicotine.

  4. Avoid alcoholic drinks before bed.

  5. Avoid large meals and beverages late at night.

  6. If possible, avoid medicines that delay or disrupt your sleep.

  7. Don’t take naps after 3 p.m.

  8. Relax before bed. Don’t overschedule your day so that no time is left for unwinding. A relaxing activity, such as reading or listening to music, should be part of your bedtime ritual.

  9. Take a hot bath or shower before bed.

  10. Dark bedroom, cool bedroom, gadget-free bedroom.

  11. Have the right sunlight exposure. Daylight is key to regulating daily sleep patterns. Try to get outside in natural sunlight for at least thirty minutes each day. If possible, wake up with the sun or use very bright lights in the morning.

  12. Don’t lie in bed awake.  For me depending on what time it is if I am awake for more than 30 mins I will just get up and start my day extra early and make sure I get an earlier than usual bed that evening.