- Two-thirds of adults throughout all developed nations fail to obtain the recommended eight hours of nightly sleep. - Society’s apathy toward sleep has, in part, been caused by the historic failure of science to explain why we need it. Sleep remained one of the last great biological mysteries. - “If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made.” Yet sleep has persisted. Heroically so. Indeed, every species studied to date sleeps. - The first factor is a signal beamed out from your internal twenty-four-hour clock located deep within your brain. The clock creates a cycling, day-night rhythm that makes you feel tired or alert at regular times of night and day, respectively. The second factor is a chemical substance that builds up in your brain and creates a “sleep pressure.” The longer you’ve been awake, the more that chemical sleep pressure accumulates, and consequentially, the sleepier you feel. It is the balance between these two factors that dictates how alert and attentive you are during the day, when you will feel tired and ready for bed at night, and, in part, how well you will sleep. - It is no coincidence that <mark style="background: #FFF3A3A6;">the likelihood of breaking an Olympic record has been clearly tied to time of day, being maximal at the natural peak of the human circadian rhythm in the early afternoon</mark>. - The suprachiasmatic nucleus controls a vast array of behaviors, including our focus in this chapter: when you want to be awake and asleep. - humans likely evolved to co-sleep as families or even whole tribes, not alone or as couples. Appreciating this evolutionary context, the benefits of such genetically programmed variation in sleep/wake timing preferences can be understood. The night owls in the group would not be going to sleep until one or two a.m., and not waking until nine or ten a.m. The morning larks, on the other hand, would have retired for the night at nine p.m. and woken at five a.m. Consequently, the group as a whole is only collectively vulnerable (i.e. every person asleep) for just four rather than eight hours, despite everyone still getting the chance for eight hours of sleep. That’s potentially a 50 percent increase in survival fitness. - of adenosine as a chemical barometer that continuously registers the amount of elapsed time since you woke up this morning. One consequence of increasing adenosine in the brain is an increasing desire to sleep. This is known as sleep pressure, and it is the second force that will determine when you feel sleepy, and thus should go to bed. - Caffeine works by successfully battling with adenosine for the privilege of latching on to adenosine welcome sites—or receptors—in the brain. Once caffeine occupies these receptors, however, it does not stimulate them like adenosine, making you sleepy. Rather, caffeine blocks and effectively inactivates the receptors, acting as a masking agent. - Sleep will not come easily or be smooth throughout the night as your brain continues its battle against the opposing force of caffeine. Most people do not realize how long it takes to overcome a single dose of caffeine, and therefore fail to make the link between the bad night of sleep we wake from in the morning and the cup of coffee we had ten hours earlier with dinner. - What you are actually experiencing during deep NREM sleep is one of the most epic displays of neural collaboration that we know of. Through an astonishing act of self-organization, many thousands of brain cells have all decided to unite and “sing,” or fire, in time. Every time I watch this stunning act of neural synchrony occurring at night in my own research laboratory, I am humbled: sleep is truly an object of awe. - Why did evolution decide to outlaw muscle activity during REM sleep? Because by eliminating muscle activity you are prevented from acting out your dream experience. During REM sleep, there is a nonstop barrage of motor commands swirling around the brain, and they underlie the movement-rich experience of dreams. - Total amount of time is one of the most conspicuous differences in how organisms sleep. You’d imagine the reason for such clear-cut variation in sleep need is obvious. It isn’t. None of the likely contenders—body size, prey/predator status, diurnal/nocturnal—usefully explains the difference in sleep need across species. - The very same effect has now been demonstrated in numerous other mammalian species, suggesting that the effect is probably common across mammals. When the infant rat pups were finally allowed to get some REM sleep, assembly of the cerebral rooftop did restart, but it didn’t accelerate, nor did it ever fully get back on track. An infant brain without sleep will be a brain ever underconstructed. - Of course, no expecting mother has to worry about scientists disrupting the REM sleep of their developing fetus. But alcohol can inflict that same selective removal of REM sleep. Alcohol is one of the most powerful suppressors of REM sleep that we know of. - 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. - In half of the participants, the researchers gently rocked the bed once they entered NREM sleep. In the other half of the subjects, the bed remained static, offering a control condition. Slow rocking increased the depth of deep sleep, boosted the quality of slow brainwaves, and more than doubled the number of sleep spindles. It is not yet known whether these sway-induced sleep changes enhance memory, since the researchers did not perform any such tests with their participants. Nevertheless, the findings offer a scientific explanation for the ancient practice of rocking a child back and forth in one’s arms, or in a crib, inducing a deep sleep. - Phrased differently, and perhaps more simply, wakefulness is low-level brain damage, while sleep is neurological sanitation. - There may well be a time in the not-too-distant future where we can accurately “read out” and thus take ownership of a process that few people have volitional control over—the dream. When this finally happens, and I’m sure it will, do we hold the dreamer responsible for what they dream? Is it fair to judge what it is they are dreaming, since they were not the conscious architect of their dream? But if they were not, then who is? It is a perplexing and uncomfortable issue to face. - REM sleep is the only time during the twenty-four-hour period when your brain is completely devoid of this anxiety-triggering molecule. - I therefore wondered whether the brain during REM sleep was reprocessing upsetting memory experiences and themes in this neurochemically calm (low noradrenaline), “safe” dreaming brain environment. Is the REM-sleep dreaming state a perfectly designed nocturnal soothing balm—one that removes the emotional sharp edges of our daily lives? It seemed so from everything neurobiology and neurophysiology was telling us (me). - Through its therapeutic work at night, REM sleep performed the elegant trick of divorcing the bitter emotional rind from the information-rich fruit. We can therefore learn and usefully recall salient life events without being crippled by the emotional baggage that those painful experiences originally carried. - But when those same participants were deprived of sleep, including the essential influence of REM sleep, they could no longer distinguish one emotion from another with accuracy. The tuning V of the brain had been changed, rudely pulled all the way up from the base and flattened into a horizontal line, as if the brain was in a state of generalized hypersensitivity without the ability to map gradations of emotional signals from the outside world. Gone was the precise ability to read giveaway clues in another’s face. - it is worth noting the condition of sleep-state misperception, also known as paradoxical insomnia. Here, patients will report having slept poorly throughout the night, or even not sleeping at all. However, when these individuals have their sleep monitored objectively using electrodes or other accurate sleep monitoring devices, there is a mismatch. The sleep recordings indicate that the patient has slept far better than they themselves believe, and sometimes indicate that a completely full and healthy night of sleep occurred. Patients suffering from paradoxical insomnia therefore have an illusion, or misperception, of poor sleep that is not actually poor. - If your family’s genes mean that you could one day be struck down by the fatal inability to sleep, would you want to be told your fate? Furthermore, if you know that fate and have not yet had children, would that change your decision to do so, knowing you are a gene carrier and that you have the potential to prevent a next-step transmission of the disease? There are no simple answers, certainly none that science can (or perhaps should) offer—an additionally cruel tendril of an already heinous condition. - But did reading on the iPad actually change sleep quantity/quality above and beyond the timing of melatonin? It did, in three concerning ways. First, individuals lost significant amounts of REM sleep following iPad reading. Second, the research subjects felt less rested and sleepier throughout the day following iPad use at night. Third was a lingering aftereffect, with participants suffering a ninety-minute lag in their evening rising melatonin levels for several days after iPad use ceased—almost like a digital hangover effect. - The need to dump heat from our extremities is also the reason that you may occasionally stick your hands and feet out from underneath the bedcovers at night due to your core becoming too hot, usually without your knowing. - Waking up at the same time of day, every day, no matter if it is the week or weekend is a good recommendation for maintaining a stable sleep schedule if you are having difficulty with sleep. - If you compare natural, deep-sleep brainwave activity to that induced by modern-day sleeping pills, such as zolpidem (brand name Ambien) or eszopiclone (brand name Lunesta), the electrical signature, or quality, is deficient. - Most controversial and alarming are those highlighted by Dr. Daniel Kripke, a physician at the University of California, San Diego. Kripke discovered that individuals using prescription sleep medications are significantly more likely to die and to develop cancer than those who do not. - if you can only adhere to one of these each and every day, make it: going to bed and waking up at the same time of day no matter what. It is perhaps the single most effective way of helping improve your sleep, even though it involves the use of an alarm clock. - It is clear that a sedentary life is one that does not help with sound sleep, and all of us should try to engage in some degree of regular exercise to help maintain not only the fitness of our bodies but also the quantity and quality of our sleep. Sleep, in return, will boost your fitness and energy, setting in motion a positive, self-sustaining cycle of improved physical activity (and mental health). - There remains a contrived, yet fortified, arrogance in many business cultures focused on the uselessness of sleep. It is bizarre, considering how sensible the professional world is regarding all other areas of employee health, safety, and conduct. - The first, and less important, is simply on grounds of pragmatism. In the context of interrogation, sleep deprivation is ill designed for the purpose of obtaining accurate, and thus actionable, intelligence. A lack of sleep, even moderate amounts, degrades every mental faculty necessary to obtain valid information, as we have seen. - Children from lower socioeconomic backgrounds are less likely to be taken to school in a car, in part because their parents often have jobs in the service industry demanding work start times at or before six a.m. Such children therefore rely on school buses for transit, and must wake up earlier than those taken to school by their parents. As a result, those already disadvantaged children become even more so because they routinely obtain less sleep than children from more affluent families. The upshot is a vicious cycle that perpetuates from one generation to the next—a closed-loop system that is very difficult to break out of. We desperately need active intervention methods to shatter this cycle, and soon. - there are people sitting in prison cells, and have been for decades, because they were caught selling amphetamines to minors on the street. However, we seem to have no problem at all in allowing pharmaceutical companies to broadcast prime-time commercials highlighting ADHD and promoting the sale of amphetamine-based drugs (e.g., Adderall, Ritalin). To a cynic, this seems like little more than an uptown version of a downtown drug pusher. - The answer originates with the esteemed physician William Stewart Halsted, MD, who was also a helpless drug addict. Halsted founded the surgical training program at Johns Hopkins Hospital in Baltimore, Maryland, in May 1889. As chief of the Department of Surgery, his influence was considerable, and his beliefs about how young doctors must apply themselves to medicine, formidable. There was to be a six-year residency, quite literally. The term “residency” came from Halsted’s belief that doctors must live in the hospital for much of their training, allowing them to be truly committed in their learning of surgical skills and medical knowledge. - The injurious consequences are well documented. Residents working a thirty-hour-straight shift will commit 36 percent more serious medical errors, such as prescribing the wrong dose of a drug or leaving a surgical implement inside of a patient, compared with those working sixteen hours or less. Additionally, after a thirty-hour shift without sleep, residents make a whopping 460 percent more diagnostic mistakes in the intensive care unit than when well rested after enough sleep. - Everyone would be present during a core window for key interactions—say, twelve to three p.m. Yet there would be flexible tail ends either side to accommodate all individual chronotypes. Owls could start work late (e.g., noon) and continue into the evening, giving their full force of mental capacity and physical energy to their jobs. Larks can likewise do so with early start and finish times, preventing them from having to coast through the final hours of the “standard” workday with inefficient sleepiness. # 12 tips: 1. Stick to a sleep schedule. Go to bed and wake up at the same time each day. As creatures of habit, people have a hard time adjusting to changes in sleep patterns. Sleeping later on weekends won’t fully make up for a lack of sleep during the week and will make it harder to wake up early on Monday morning. Set an alarm for bedtime. Often we set an alarm for when it’s time to wake up but fail to do so for when it’s time to go to sleep. If there is only one piece of advice you remember and take from these twelve tips, this should be it. 2. Exercise is great, but not too late in the day. Try to exercise at least thirty minutes on most days but not later than two to three hours before your bedtime. 3. Avoid caffeine and nicotine. Coffee, colas, certain teas, and chocolate contain the stimulant caffeine, and its effects can take as long as eight hours to wear off fully. Therefore, a cup of coffee in the late afternoon can make it hard for you to fall asleep at night. Nicotine is also a stimulant, often causing smokers to sleep only very lightly. In addition, smokers often wake up too early in the morning because of nicotine withdrawal. 4. Avoid alcoholic drinks before bed. Having a nightcap or alcoholic beverage before sleep may help you relax, but heavy use robs you of REM sleep, keeping you in the lighter stages of sleep. Heavy alcohol ingestion also may contribute to impairment in breathing at night. You also tend to wake up in the middle of the night when the effects of the alcohol have worn off. 5. Avoid large meals and beverages late at night. A light snack is okay, but a large meal can cause indigestion, which interferes with sleep. Drinking too many fluids at night can cause frequent awakenings to urinate. 6. If possible, avoid medicines that delay or disrupt your sleep. Some commonly prescribed heart, blood pressure, or asthma medications, as well as some over-the-counter and herbal remedies for coughs, colds, or allergies, can disrupt sleep patterns. If you have trouble sleeping, talk to your health care provider or pharmacist to see whether any drugs you’re taking might be contributing to your insomnia and ask whether they can be taken at other times during the day or early in the evening. 7. Don’t take naps after 3 p.m. Naps can help make up for lost sleep, but late afternoon naps can make it harder to fall asleep at night. 8. Relax before bed. Don’t over schedule 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 before bed. The drop in body temperature after getting out of the bath may help you feel sleepy, and the bath can help you relax and slow down so you’re more ready to sleep. 10. Dark bedroom, cool bedroom, gadget-free bedroom. Get rid of anything in your bedroom that might distract you from sleep, such as noises, bright lights, an uncomfortable bed, or warm temperatures. You sleep better if the temperature in the room is kept on the cool side. A TV, cell phone, or computer in the bedroom can be a distraction and deprive you of needed sleep. Having a comfortable mattress and pillow can help promote a good night’s sleep. Individuals who have insomnia often watch the clock. Turn the clock’s face out of view so you don’t worry about the time while trying to fall asleep. 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. Sleep experts recommend that, if you have problems falling asleep, you should get an hour of exposure to morning sunlight and turn down the lights before bedtime. 12. Don’t lie in bed awake. If you find yourself still awake after staying in bed for more than twenty minutes or if you are starting to feel anxious or worried, get up and do some relaxing activity until you feel sleepy. The anxiety of not being able to sleep can make it harder to fall asleep.