Disclaimer: This article (and the book it is based on) discuss the consequences of not getting enough sleep, which may provoke or exacerbate sleep-related anxieties.
Before reading, please refer to this brief note detailing some issues with Why We Sleep.
Sleep—if you’re like the majority of people living in the developed world, you’re probably not getting enough of it.1 Matthew Walker, a professor of neuroscience and psychology at UC Berkeley, is here to spell out why that’s a problem. What follows is a selection of the most fascinating (or perhaps terrifying) research from his bestselling book, Why We Sleep,2a forthright look at the dire consequences that can result from a lack of shuteye.
There does not seem to be one major organ within the body, or process within the brain, that isn’t optimally enhanced by sleep (and detrimentally impaired when we don’t get enough). . . . No facet of the human body is spared the crippling, noxious harm of sleep loss. . . . Every major system, tissue, and organ of your body suffers when sleep becomes short. No aspect of your health can retreat at the sign of sleep loss and escape unharmed. Like water from a burst pipe in your home, the effects of sleep deprivation will seep into every nook and cranny of biology, down into your cells, even altering your most fundamental self—your DNA. . . . Neglect sleep, and you are deciding to perform a genetic engineering manipulation on yourself each night, tampering with the nucleic alphabet that spells out your daily health story. Permit the same in your children and teenagers, and you are imposing a similar genetic engineering experiment on them as well.
Yikes . . .
Walker’s conclusions are informed by more than twenty epidemiological studies (following millions of people over decades) that have observed a consistent relationship between sleep loss and mortality, concisely summarised as: ‘the shorter your sleep, the shorter your life.’ If you routinely fail to get 7-9 hours of sleep per night (considered the optimal range for adults by the National Sleep Foundation), your life is likely to be shortened due to an increased risk of cancer, heart disease, Alzheimer’s disease, diabetes, obesity, and suicide.
Sleep Loss: A Debt You Can’t Repay?
One of the reasons sleep loss is so hazardous to our health is that it impairs immune function. A study monitoring the sleeping habits of a group of participants who were later exposed to the common cold virus, found that almost half of those who slept less than 5 hours per night became infected. In contrast, only 18 percent of those sleeping 7 hours or more per night got sick.3
Such immune deficiencies can persist long after the period in which the sleep loss originally occurred. According to Walker, impaired immune function can be observed a year after ‘a minor, short dose of sleep restriction.’
It would appear that running a sleep deficit during the week with the hope of balancing your sleep budget at the weekend, is a losing strategy—that is, if you care about maintaining an optimally functioning immune system. That said, authors of a 2017 study suggested that it may indeed be possible to pre-emptively ‘bank’ sleep before a period of sleep deprivation, in order to improve physical and cognitive performance.
Sleep Loss, Weight Gain
If you want to lose weight, more time in bed (rather than the gym4) may be the answer. Walker points out that insufficient sleep increases levels of a hunger-inducing hormone whilst, at the same time, inhibiting a hormone signaling satiation. As a result, sleep-deprived people may find themselves eating more than they otherwise would. Consuming extra calories in the form of broccoli and kale probably isn’t going to widen your waistline. But according to Walker and colleagues’ research, you are more likely to be craving (and consuming) the contents of your kitchen cookie jar.5
If you are keen on exercising to lose weight, getting enough sleep may also help to keep you injury-free. Walker cites research that has observed a dose-dependent relationship between sleep loss and sports injuries.6 In other words, the less you sleep on average, the more injury-prone you become.
Caffeine and the Myth of ‘Decaf’
Did you know that ‘decaffeinated’ coffee does actually contain caffeine? Walker, to the dismay of his decaf-drinking readers, notes that an average cup of decaf contains 15-30 percent of the caffeine found in a regular coffee. So if you’re drinking decaf with reckless abandon, don’t think it isn’t having an effect on your brain.
What effect? Caffeine inhibits the effects of adenosine, a chemical that accumulates in your brain whilst awake and causes you to feel sleepy (typically after 12-16 hours of wakefulness). Once the consumed caffeine is removed by your liver (which can take several hours), all of that built-up adenosine floods into your brain’s vacant receptor sites, causing intense fatigue.
Your Designated Driver is Less Capable than You Think
If you think you’re being responsible by nominating someone to forgo alcohol in order to drive you and your friends home safely after a night of drinking, you might want to reconsider. Assuming your designated driver wakes up at 7 am, goes to work, and then later accompanies you on your drunken escapades into the early hours of the next morning, when it comes time to drive you home, his attention will be as impaired as it would be if he were to meet the legal drink driving limit.
Walker goes on to point out that ‘vehicle accidents caused by drowsy driving exceed those caused by alcohol and drugs combined.’ Why? When you’re drunk, you react more slowly to potential hazards; when you’re asleep, you don’t react at all.
Whilst urging readers to take the issue of drowsy driving more seriously, Walker bemoans its lack of attention from governmental institutions:
Shamefully, governments of most developed countries spend less than 1 percent of their budget educating the public on the dangers of drowsy driving relative to what they invest in combating drunk driving.
‘There is no major psychiatric condition in which sleep is normal’
If you are feeling depressed, anxious, or experiencing other forms of psychological distress, you are probably not sleeping well. Sleep loss is also linked to suicide. According to Walker, the most common cause of insomnia is anxiety and the most common remedy is sleeping pills.
Millions of Americans take sleeping pills.7 These pills do not stimulate natural sleep. Instead, like alcohol, they merely sedate you. They also increase mortality. Dr Daniel F. Kripke has compiled a list of studies showing a link between sleeping pills and higher mortality rates.
Fortunately, there are safer and more effective alternatives to sleeping pills. For example, cognitive behavioural therapy for insomnia (CBT-I) has been shown to be superior, producing longer-lasting positive effects without the harmful side effects of sleeping pills. Its effectiveness has led the American College of Physicians to state that CBT-I ‘should be the first-line treatment for adults with chronic insomnia’.8
“What’s my diagnosis, Doc?” “You have ADHD Sleep Deficiency”
Despite being considered a ‘brain disorder’9 by some researchers, ‘ADHD’, like all other psychiatric diagnoses, is not based on any objective laboratory tests.10 Instead, a diagnosis is made using a checklist of highly subjective descriptions such as, ‘difficulty sustaining attention’, ‘does not seem to listen’, and ‘often on the go’.11
Thankfully, Walker does not appear to buy in to the idea that ‘ADHD’ is the product of a broken brain,12 observing that many of the ‘symptoms’ associated with ‘ADHD’ mirror behaviours (e.g. inattention, learning difficulties) consistent with a lack of sleep.
Based on recent surveys and clinical evaluations, we estimate that more than 50 percent of all children with an ADHD diagnosis actually have a sleep disorder, yet a small fraction know of their sleep condition and its ramifications.
He also notes that the most commonly prescribed drugs for ‘ADHD’ (e.g. methylphenidate) prevent natural sleep.
Before He Reaches for the Scalpel, Ask Your Doctor When He Last Slept
Medical errors are the third leading cause of death in the US.13 One reason for this is that doctors work extremely long shifts. Walker notes that a resident working ‘a thirty-hour-straight shift will commit 36 percent more serious medical errors’ and ‘460 percent more diagnostic mistakes’. Inevitably, some of these mistakes are fatal: ‘one in five medical residents will make a sleepless-related medical error that causes significant, liable harm to a patient’ and ‘[o]ne in twenty residents will kill a patient due to a lack of sleep.’
Testicles
We conclude by briefly mentioning the discoveries Walker is perhaps most famous for jovially pointing out; i.e., that sleep loss is linked to lower testosterone levels, lower sperm counts, lower sperm quality, and you guessed it, smaller testicles.14
Ready for Bed?
The reward for making it through Why We Sleep’s frightful tour of sleep-mediated maladies, is a list of tips for improving your sleep, courtesy of the National Institute of Health. If you’d rather take a nap, have an early night, or just save some time, you can click the right-side image for the complete list.
Footnotes
- When claiming that most people fail to get enough sleep, Walker means they do not attain the recommended average of 8-hours per night (stipulated by the World Health Organization and National Sleep Foundation). However, the National Sleep Foundation’s recommended sleep range for adults is 7-9 hours per night. A study published by the CDC showed that the majority of Americans fall within this recommended range, with only 1 in 3 failing to reach the 7 hour cut-off.
- Walker, M. (2017). Why we sleep: Unlocking the power of sleep and dreams. New York: Scribner.
- Prather, A. A., Janicki-Deverts, D., Hall, M. H., & Cohen, S. (2015). Behaviorally assessed sleep and susceptibility to the common cold. Sleep, 38(9), 1353–1359. doi:https://doi.org/10.5665/sleep.4968
- However, exercise is great for your overall health and helps to improve sleep, too.
- Greer, S. M., Goldstein, A. N., & Walker, M. P. (2013). The impact of sleep deprivation on food desire in the human brain. Nature Communications, 4(1), 1-7. doi:10.1038/ncomms3259
- Milewski, M. D., Skaggs, D. L., Bishop, G. A., Pace, J. L., Ibrahim, D. A., Wren, T. A., & Barzdukas, A. (2014). Chronic lack of sleep is associated with increased sports injuries in adolescent athletes. Journal of Pediatric Orthopaedics, 34(2), 129-133. doi:10.1097/BPO.0000000000000151
- Chong, Y., Fryar, C. D., & Gu, Q. (2013, August). Prescription sleep aid use among adults: United States, 2005–2010. Retrieved May 16, 2020, from Centers for Disease Control and Prevention: https://www.cdc.gov/nchs/products/databriefs/db127.htm
- American College of Physicians. (2016, May 3). ACP recommends cognitive behavioral therapy as initial treatment for chronic insomnia. Retrieved May 16, 2020, from ACP: https://www.acponline.org/acp-newsroom/acp-recommends-cognitive-behavioral-therapy-as-initial-treatment-for-chronic-insomnia
- Sedarati, J. (2018). Do children diagnosed with ‘ADHD’ have a brain disorder? The Journal of Critical Psychology, Counselling and Psychotherapy, 18(1), 19-29.
- British Psychological Society. (2014). Understanding psychosis and schizophrenia. Leicester: Author.
- Kirk, S. A., Gomory, T., & Cohen, D. (2013). Mad science: psychiatric coercion, diagnosis, and drugs. New Brunswick: Transaction.
- Although Walker does state, ‘I am in no way contesting the disorder of ADHD’.
- Makary, M., & Daniel, M. (2016). Medical error—the third leading cause of death in the US. BMJ, 353, 1-5.
- Walker does not include specific references for these associations in his book. He is likely referring to these two studies;
Jensen, T. K., Andersson, A., Skakkebæk, N. E., Joensen, U. N., Jensen, M. B., Lassen, T. H., . . . Jørgensen, N. (2013). Association of sleep disturbances with reduced semen quality: a cross-sectional study among 953 healthy young Danish men. American Journal of Epidemiology, 177(10), 1027–1037. doi:https://doi.org/10.1093/aje/kws420
Leproult, R., & Cauter, E. V. (2011). Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA, 305(21), 2173-2174. doi:10.1001/jama.2011.710
