The Science of Sleep
Sleep is way more important than we realize. It’s also, according to David Randall inDreamland: Adventures in the Strange Science of Sleep, “the largest overlooked part of your life and … it affects you even if you don’t have a sleep problem.”
We spend about a third of our lives asleep. Or trying to sleep. Increasingly we’re turning to prescription meds to help us sleep.
In the interest of sharing things with you, I thought I’d share my “sleep” file.
We still don’t understand much
Despite taking up so much of life, sleep is one of the youngest fields of science. Until the middle of the twentieth century, scientists thought that sleep was an unchanging condition during which time the brain was quiet. The discovery of rapid eye movements in the 1950s upended that. Researchers then realized that sleep is made up of five distinct stages that the body cycles through over roughly ninety-minute periods. The first is so light that if you wake up from it, you might not realize that you have been sleeping. The second is marked by the appearance of sleep-specific brain waves that last only a few seconds at a time. If you reach this point in the cycle, you will know you have been sleeping when you wake up. This stage marks the last drop before your brain takes a long ride away from consciousness. Stages three and four are considered deep sleep. In three, the brain sends out long, rhythmic bursts called delta waves. Stage four is known as slow-wave sleep for the speed of its accompanying brain waves. The deepest form of sleep, this is the farthest that your brain travels from conscious thought. If you are woken up while in stage four, you will be disoriented, unable to answer basic questions, and want nothing more than to go back to sleep, a condition that researchers call sleep drunkenness. The final stage is REM sleep, so named because of the rapid movements of your eyes dancing against your eyelids. In this stage of sleep, the brain is as active as it is when it is awake. This is when most dreams occur.
Sleep is more important than food
Sleep is more important than food when it comes to improving performance.
In Anders Ericsson’s famous study of violinists, the top performers slept an average of 8 hours out of every 24, including a 20 to 30 minute midafternoon nap some 2 hours a day more than the average American.The top violinists also reported that, except for practice itself, sleep was the second most important factor in improving as violinists.
Sleep improves thinking
The bottom line is that sleep loss means mind loss. Sleep loss cripples thinking, in just about every way you can measure thinking. Sleep loss hurts attention, executive function, immediate memory, working memory, mood, quantitative skills, logical reasoning ability, general math knowledge.
Sleeping makes you happier
Negative stimuli get processed by the amygdala; positive or neutral memories gets processed by the hippocampus. Sleep deprivation hits the hippocampus harder than the amygdala. The result is that sleep-deprived people fail to recall pleasant memories, yet recall gloomy memories just fine. In one experiment by Walker, sleep-deprived college students tried to memorize a list of words. They could remember 81% of the words with a negative connotation, like “cancer.” But they could remember only 31% of the words with a positive or neutral connotation, like “sunshine” or “basket.”
Napping is normal
Napping is normal. Ever feel tired in the afternoon? That’s because your brain really wants to take a nap. There’s a battle raging in your head between two armies. Each army is made of legions of brain cells and biochemicals –- one desperately trying to keep you awake, the other desperately trying to force you to sleep. Around 3 p.m., 12 hours after the midpoint of your sleep, all your brain wants to do is nap.
Napping and sleeping also help make you smarter: “sleep is needed to clear the brain’s short-term memory storage and make room for new information.”
Sleep on it
You should sleep on it:
“There is something to be gained from taking a night to sleep on it when you’re facing an important decision. We found that the fact that you slept makes your decisions better.”
How much sleep do we need?
More than Napoleon famously advised: “Six hours’ sleep for a man, seven for a woman, and eight for a fool.”
Is it just me or has the ability to function on less sleep become some cultural badge of honour these days? The assumption that whoever can still ‘do their job’ on less sleep wins? I’m as guilty as anyone.
Lions and gerbils sleep about thirteen hours a day. Tigers and squirrels nod off for about fifteen hours. At the other end of the spectrum, elephants typically sleep three and a half hours at a time, which seems lavish compared to the hour and a half of shut-eye that the average giraffe gets each night.…Humans need roughly one hour of sleep for every two hours they are awake, and the body innately knows when this ratio becomes out of whack. Each hour of missed sleep one night will result in deeper sleep the next, until the body’s sleep debt is wiped clean.
Teenagers need more sleep
Teenagers need around eight to ten hours of sleep but get much less during their workweek. A recent study found that when the starting time of high school is delayed by an hour, the percentage of students who get at least eight hours of sleep per night jumps from 35.7 percent to 50 percent. Adolescent students’ attendance rate, their performance, their motivation, even their eating habits all improve significantly if school times are delayed.
Are Early Risers Better People
This myth that early risers are good people and that late risers are lazy has its reasons and merits in rural societies but becomes questionable in a modern 24/7 society. The old moral is so prevalent, however, that it still dominates our beliefs, even in modern times. The postman doesn’t think for a second that the young man might have worked until the early morning hours because he is a night-shift worker or for other reasons. He labels healthy young people who sleep into the day as lazy — as long sleepers. This attitude is reflected in the frequent use of the word-pair early birds and long sleepers. Yet this pair is nothing but apples and oranges, because the opposite of early is late and the opposite of long is short.
Stress impacts your ability to sleep.
Stress damages virtually every kind of cognition that exists. It damages memory and executive function. It can hurt your motor skills. When you are stressed out over a long period of time it disrupts your immune response. You get sicker more often. It disrupts your ability to sleep. You get depressed.
But, I can’t sleep
When you can’t sleep, should you lie in bed with your eyes closed? No.
Brian Fung answers in the Atlantic.
Brian Fung answers in the Atlantic.
The useful takeaway is that your best move, if you’ve been in bed for 20 minutes and still aren’t dozing off, is to get up and engage in a low-light, low-stress activity like reading until you begin to feel tired. Taking your mind off of “Why am I not sleeping?! I need to sleep!” is crucial. When you do get up, though, don’t use your computer or phone or watch TV — the blue-colored light from the screens tricks your body into thinking it’s daytime and not releasing melatonin.
Does jet-lag affect performance?
In a word: yes.
The Stanford researchers dug through twenty-five years of Monday night NFL games and flagged every time a West Coast team played an East Coast team. Then, in an inspired move, they compared the final scores for each game with the point spread developed by bookmakers in Vegas. The results were stunning. The West Coast teams dominated their East Coast opponents no matter where they played. A West Coast team won 63 percent of the time, by an average of two touchdowns. The games were much closer when an East Coast team won, with an average margin of victory of only nine points. By picking the West Coast team every time, someone would have beaten the point spread 70 percent of the time. For gamblers in Las Vegas, the matchup was as good as found money.…“The kiss of death is shifting three time zones,” he said. Teams that flew to the opposite coast were twice as likely to be beaten by a lower-ranked opponent in the tournament’s first round. Circadian schedules trumped natural ability. The circadian advantage— or disadvantage, depending on your perspective– popped up in studies of figure skaters, rowers, golfers, baseball players, swimmers, and divers. Everywhere you turned, there was evidence of the body’s hidden rhythms at work. One study found that in sports as varied as running, weightlifting, and swimming, athletes competing when their bodies experienced the second boost of circadian energy were more likely to break a world record. Long jumpers, for instance, launched themselves nearly 4 percent farther when the body was at its circadian peak. But the circadian rhythm cut both ways. Athletes competing when their circadian rhythm corresponded to the so-called sleep gates— those times in the early afternoon or late nights when it’s easy for most people to fall asleep— consistently performed a little worse than normal, even if the slowdown wasn’t obvious to them.
Why Do We Dream?
Despite differences in terminology, all the contemporary theories of dreaming have a common thread — they all emphasize that dreams are not about prosaic themes, not about reading, writing, and arithmetic, but about emotion, or what psychologists refer to as affect. What is carried forward from waking hours into sleep are recent experiences that have an emotional component, often those that were negative in tone but not noticed at the time or not fully resolved. One proposed purpose of dreaming, of what dreaming accomplishes (known as the mood regulatory function of dreams theory) is that dreaming modulates disturbances in emotion, regulating those that are troublesome. My research, as well as that of other investigators in this country and abroad, supports this theory. Studies show that negative mood is down-regulated overnight. How this is accomplished has had less attention.I propose that when some disturbing waking experience is reactivated in sleep and carried forward into REM, where it is matched by similarity in feeling to earlier memories, a network of older associations is stimulated and is displayed as a sequence of compound images that we experience as dreams. This melding of new and old memory fragments modifies the network of emotional self-defining memories, and thus updates the organizational picture we hold of ‘who I am and what is good for me and what is not.’ In this way, dreaming diffuses the emotional charge of the event and so prepares the sleeper to wake ready to see things in a more positive light, to make a fresh start. This does not always happen over a single night; sometimes a big reorganization of the emotional perspective of our self-concept must be made — from wife to widow or married to single, say, and this may take many nights. We must look for dream changes within the night and over time across nights to detect whether a productive change is under way. In very broad strokes, this is the definition of the mood-regulatory function of dreaming, one basic to the new model of the twenty-four hour mind I am proposing.
Daylight savings time.
Studies have shown that disrupting circadian rhythms by even one hour during the switch to daylight saving time may increase depression, traffic accidents, and heart attacks. These rhythms affect consumption and metabolism in animals—it is hard to imagine that they aren’t also playing a role in human appetites as well. Controlling environmental light with lamps, TVs, and computers gives us incredible flexibility and productivity. But it interrupts daily and yearly cycles that were billions of years in the making and are shared by countless creatures on our planet.
What causes insomnia?
The cause is often the brain’s refusal to give up its unequaled ability to think about itself, a meta-phenomenon that Harvard professor Daniel M. Wegner has called “the ironic process of mental control.” To illustrate this concept, imagine someone telling you that you will be judged on how quickly you can relax. Your initial reaction most likely is to tighten up. After he posed that challenge to research subjects, Wegner found that the average person becomes anxious as his or her mind constantly monitors its progress toward its goal, caught up in the second-by-second process of self-assessment. In the same way, sleep becomes more elusive as a person’s sleep needs become more urgent. This problem compounds itself each night, leading to a state of chronic insomnia.…Patients with insomnia tend to think that one night of poor sleep leads to immediate health problems or has an outsized impact on their mood the next day, a mental pressure cooker that leaves them fretting that every second they are awake in the middle of the night is another grain of salt in the wound. In the inverted logic of the condition, sleep is extremely important to someone with insomnia. Therefore, the person with insomnia can’t get sleep.
Good sleepers have an active mind
[In] good sleepers, the mind is continuously active, reviewing experience from yesterday, sorting which new information is relevant and important to save due to its emotional saliency. Dreams are not without sense, nor are they best understood to be expressions of infantile wishes. They are the result of the interconnectedness of new experience with that already stored in memory networks. But memory is never a precise duplicate of the original; instead, it is a continuing act of creation. Dream images are the product of that creation. They are formed by pattern recognition between some current emotionally valued experience matching the condensed representation of similarly toned memories. Networks of these become our familiar style of thinking, which gives our behavior continuity and us a coherent sense of who we are. Thus, dream dimensions are elements of the schemas, and both represent accumulated experience and serve to filter and evaluate the new day’s input.
Ok, ok, I hear you saying. Get to the tips already.
How you can sleep better
First, we need to understand what goes into a good night of sleep?
Only recently has science figured out what goes into a good night of sleep. Falling asleep, and staying that way throughout the night, appears to be a battle with two fronts. The first takes place in the head. Between the time when a person lays his or her head on a pillow and the time when the brain sends out the first sleep spindles marking the onset of sleep, the mind must put aside its focus on its immediate surroundings and daily concerns. This process requires a person to give up direct control of his or her thoughts. At the same time, the body must be comfortable enough that the brain essentially forgets that they are attached. When something gets in the way of either, the result is often insomnia.
Mattresses don’t matter.
while a comfortable mattress may have little impact when it comes to sleep quality, there are several other aspects of the bedroom that do. Taken together, they form what specialists call sleep hygiene. Most are common sense. It is obviously not a good idea to drink coffee in the evening if it keeps you up at night. Nor is drinking alcohol before bedtime a smart move. Alcohol may help speed the onset of sleep, but it begins to take its toll during the second half of the night. As the body breaks down the liquid, the alcohol in the bloodstream often leads to an increase in the number of times a person briefly wakes up. This continues until the blood alcohol level returns to zero, thereby preventing the body from getting a full, deep, restorative sleep.
Help your circadian rhythm by knowing when to use light and when to avoid it.
Via Dreamland: Adventures in the Strange Science of Sleep:
Via Dreamland: Adventures in the Strange Science of Sleep:
…bright lights—including the blue-and-white light that comes from a computer monitor or a television screen—can deceive the brain, which registers it as daylight. Lying in bed watching a movie on an iPad may be relaxing, but the constant bright light from the screen can make it more difficult for some people to fall asleep afterward.
Cold showers and why we stick our feet out.
Via Dreamland: Adventures in the Strange Science of Sleep:
Via Dreamland: Adventures in the Strange Science of Sleep:
Recent studies have shown that body temperature also plays an outsized role in getting decent sleep. In addition to the appearance of brain waves like sleep spindles, one of the biological markers of the onset of sleep is a drop in core body temperature. At the same time, the temperature of the feet and hands increases as the body gives off heat through its periphery, which explains why some people like to have their feet sticking out of the covers as they fall asleep. The bodys tendency to release heat during the night is one reason why some mattresses are said to be uncomfortable—they “sleep hot.” In the simplest explanation, the fabric and materials that make up some beds trap the heat the body is reassessing.…Assisting the body in its cooling process, then is a natural way to improve sleep. One study by researchers in Lille, a city in northeastern France, found that subjects fell asleep faster and had a better overall quality of sleep following behaviors that cooled the body, such as taking a cold shower right before bed. The best predictor of quality sleep was maintaining a room temperature in a narrow band between 60 and 66 degrees Fahrenheit (or 16 to 19 degrees Celsius)
Exercise helps. “Those who exercised reported a better quality of sleep than those who remained sedentary.”
Other common suggestions from sleep doctors include maintaining a consistent bedtime, using the bedroom only for sex or sleeping, and turning the lights down low in the home about a half hour before climbing into bed.
The Age of Always On
The most important point in Dreamland might be that our round the clock non-stop world is throwing ourselves into.
We are living in an age when sleep is more comfortable than ever and yet more elusive. Even the worst dorm-room mattress in America is luxurious compared to sleeping arrangements that were common not long ago. During the Victorian era, for instance, laborers living in workhouses slept sitting on benches, with their arms dangling over a taut rope in front of them. They paid for this privilege, implying that it was better than the alternatives. Families up to the time of the Industrial Revolution engaged in the nightly ritual of checking for rats and mites burrowing in the one shared bedroom. Modernity brought about a drastic improvement in living standards, but with it came electric lights, television, and other kinds of entertainment that have thrown our sleep patterns into chaos.Work has morphed into a twenty-four-hour fact of life, bringing its own set of standards and expectations when it comes to sleep … Sleep is ingrained in our cultural ethos as something that can be put off, dosed with coffee, or ignored. And yet maintaining a healthy sleep schedule is now thought of as one of the best forms of preventative medicine.
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