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July 10 - August 11, 2020
All humans, irrespective of culture or geographical location, have a genetically hardwired dip in alertness that occurs in the midafternoon hours. Observe any post-lunch meeting around a boardroom table and this fact will become evidently clear. Like puppets whose control strings were let loose, then rapidly pulled taut, heads will start dipping then quickly snap back upright.
Both you and the meeting attendees are falling prey to an evolutionarily imprinted lull in wakefulness that favors an afternoon nap, called the post-prandial alertness dip (from the Latin prandium, “meal”).
What becomes clearly apparent when you step back from these details is that modern society has divorced us from what should be a preordained arrangement of biphasic sleep—one that our genetic code nevertheless tries to rekindle every afternoon.
Accepting that this is our natural pattern of slumber, can we ever know for certain what types of health consequences have been caused by our abandonment of biphasic sleep?
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.
It is perhaps unsurprising that in the small enclaves of Greece where siestas still remain intact, such as the island of Ikaria, men are nearly four times as likely to reach the age of ninety as American males.
Think of REM sleep like an Internet service provider that populates new neighborhoods of the brain with vast networks of fiber-optic cables. Using these inaugural bolts of electricity, REM sleep then activates their high-speed functioning.
Certainly sleep is not the only factor in the ripening of the brain, but it appears to be a significant one that paves the way to mature thinking and reasoning ability.
It takes deep sleep, and developmental time, to accomplish the neural maturation that plugs this brain “gap” within the frontal lobe. When your children finally reach their mid-twenties and your car insurance premium drops, you can thank sleep for the savings.
In a separate series of studies, we have also observed that in young individuals who are at high risk of developing schizophrenia, and in teenagers and young adults with schizophrenia, there is a two- to threefold reduction in deep NREM sleep.
I will address the harmful and life-threatening effects of the latter in a later chapter; however, the complications of early school start times are inextricably linked with the first issue—a shift in circadian rhythm.
This, of course, leads to much angst and frustration for all parties involved on the back end of sleep. Parents want their teenager to be awake at a “reasonable” hour of the morning. Teenagers, on the other hand, having only been capable of initiating sleep some hours after their parents, can still be in their trough of the circadian downswing. Like an animal prematurely wrenched out of hibernation too early, the adolescent brain still needs more sleep and more time to complete the circadian cycle before it can operate efficiently, without grogginess.
If this remains perplexing to parents, a different way to frame and perhaps appreciate the mismatch is this: asking your teenage son or daughter to go to bed and fall asleep at ten p.m. is the circadian equivalent of asking you, their parent, to go to sleep at seven or eight p.m. No matter how loud you enunciate the order, no matter how much that teenager truly wishes to obey your instruction, and no matter what amount of willed effort is applied by either of the two parties, the circadian rhythm of a teenager will not be miraculously coaxed into a change.
Scientists have discovered a revolutionary new treatment that makes you live longer. It enhances your memory and makes you more creative. It makes you look more attractive. It keeps you slim and lowers food cravings. It protects you from cancer and dementia. It wards off colds and the flu. It lowers your risk of heart attacks and stroke, not to mention diabetes. You’ll even feel happier, less depressed, and less anxious. Are you interested?
Of course, the ad is not describing some miracle new tincture or a cure-all wonder drug, but rather the proven benefits of a full night of sleep. The evidence supporting these claims has been documented in more than 17,000 well-scrutinized scientific reports to date.
Sleep before learning refreshes our ability to initially make new memories.
Those who were awake throughout the day became progressively worse at learning, even though their ability to concentrate remained stable (determined by separate attention and response time tests). In contrast, those who napped did markedly better, and actually improved in their capacity to memorize facts. The difference between the two groups at six p.m. was not small: a 20 percent learning advantage for those who slept.
sleep restores the brain’s capacity for learning, making room for new memories,
The second benefit of sleep for memory comes after learning, one that effectively clicks the “save” button on those newly created files.
Time spent asleep helped cement the newly learned chunks of information, preventing them from fading away. In contrast, an equivalent time spent awake was deeply hazardous to recently acquired memories, resulting in an accelerated trajectory of forgetting.
memory retention benefit of between 20 and 40 percent being offered by sleep,
Struck by the weight of damning scientific evidence, the Guinness Book of World Records has stopped recognizing attempts to break the sleep deprivation world record.
sleep loss inflicts such devastating effects on the brain, linking it to numerous neurological and psychiatric conditions (e.g., Alzheimer’s disease, anxiety, depression, bipolar disorder, suicide, stroke, and chronic pain), and 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. We are, as you will see, socially, organizationally, economically, physically, behaviorally,
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Every hour, someone dies in a traffic accident in the US due to a fatigue-related error.
Slowness was not the most sensitive signature of sleepiness, entirely missed responses were. Dinges was capturing lapses, otherwise known as microsleeps: the real-life equivalent of which would be failing to react to a child who runs out in front of your car when chasing a ball.
Those individuals who slept eight hours every night maintained a stable, near-perfect performance across the two weeks. Those in the three-night total sleep deprivation group suffered catastrophic impairment, which was no real surprise. After the first night of no sleep at all, their lapses in concentration (missed responses) increased by over 400 percent. The surprise was that these impairments continued to escalate at the same ballistic rate after a second and third night of total sleep deprivation, as if they would continue to escalate in severity if more nights of sleep were lost, showing
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After four hours of sleep for six nights, participants’ performance was just as bad as those who had not slept for twenty-four hours straight—that is, a 400 percent increase in the number of microsleeps.
Most worrying from a societal perspective were the individuals in the group who obtained six hours of sleep a night—something that may sound familiar to many of you. Ten days of six hours of sleep a night was all it took to become as impaired in performance as going without sleep for twenty-four hours straight.
And like the total sleep deprivation group, the accruing performance impairment in the four-hour and six-hour sleep groups showed no signs of leveling out. All signs suggested that if the experiment had continued, the performance deterioration would continue to build up over weeks or months.
The third key finding, common to both of these studies, is the one I personally think is the most harmful of all. When participants were asked about their subjective sense of how impaired they were, they consistently underestimated their degree of performance disability.
Similarly problematic is baseline resetting. 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. Individuals fail to recognize how their perennial state of sleep deficiency has come to compromise their mental aptitude and physical vitality, including the slow accumulation of ill health.
Based on epidemiological studies of average sleep time, millions of individuals unwittingly spend years of their life in a sub-optimal state of psychological and physiological functioning, never maximizing their potential of mind or body due to their blind persistence in sleeping too little. 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.”
In a disturbing later study, researchers in Australia took two groups of healthy adults, one of whom they got drunk to the legal driving limit (.08 percent blood alcohol), the other of whom they sleep-deprived for a single night. Both groups performed the concentration test to assess attention performance, specifically the number of lapses. After being awake for nineteen hours, people who were sleep-deprived were as cognitively impaired as those who were legally drunk.
In fact, participants in the above study started their nosedive in performance after just fifteen hours of being awake
Operating on less than five hours of sleep, your risk of a car crash increases threefold. Get behind the wheel of a car when having slept just four hours or less the night before and you are 11.5 times more likely to be involved in a car accident. Note how the relationship between decreasing hours of sleep and increasing mortality risk of an accident is not linear, but instead exponentially mushrooms.
After thirty years of intensive research, we can now answer many of the questions posed earlier. The recycle rate of a human being is around sixteen hours. After sixteen hours of being awake, the brain begins to fail. Humans need more than seven hours of sleep each night to maintain cognitive performance. 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. Three full nights of recovery sleep (i.e., more nights than a weekend) are insufficient to restore performance back to normal levels after a week of short
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This coming week, more than 2 million people in the US will fall asleep while driving their motor vehicle. That’s more than 250,000 every day, with more such events during the week than weekends for obvious reasons. More than 56 million Americans admit to struggling to stay awake at the wheel of a car each month. As a result, 1.2 million accidents are caused by sleepiness each year in the United States.
for every thirty seconds you’ve been reading this book, there has been a car accident somewhere in the US caused by sleeplessness.
You may find it surprising to learn that vehicle accidents caused by drowsy driving exceed those caused by alcohol and drugs combined. Drowsy driving alone is worse than driving drunk.
Yet my statement is true for the following simple reason: drunk drivers are often late in braking, and late in making evasive maneuvers. But when you fall asleep, or have a microsleep, you stop reacting altogether. A person who experiences a microsleep or who has fallen asleep at the wheel does not brake at all, nor do they make any attempt to avoid the accident. As a result, car crashes caused by drowsiness tend to be far more deadly than those caused by alcohol or drugs.
As a result, these truck drivers are 200 to 500 percent more likely to be involved in a traffic accident. And when a truck driver loses his or her life in a drowsy-driving crash, they will, on average, take 4.5 other lives with them.
There are many things that I hope readers take away from this book. This is one of the most important: if you are drowsy while driving, please, please stop. It is lethal.
It is during this end phase of flight, known in the aviation industry as “top of descent to landing,” that 68 percent of all hull losses—a euphemism for a catastrophic plane crash—occur.
Brief power naps have become synonymous with the inaccurate assumption that they allow an individual to forgo sufficient sleep, night after night, especially when combined with the liberal use of caffeine.
No matter what you may have heard or read in the popular media, there is no scientific evidence we have suggesting that a drug, a device, or any amount of psychological willpower can replace sleep.
Currently, however, there is no drug that has the proven ability to replace those benefits that a full night of sleep infuses into the brain and body.
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.
Having learned this, I imagine that some readers now believe that they are one of these individuals. That is very, very unlikely.
The gene is remarkably rare, with but a soupçon of individuals in the world estimated to carry this anomaly.
“The number of people who can survive on five hours of sleep or less without any impairment, expressed as a percent of the population, and rounded to a whole number, is zero.”
