THE SCIENCE OF SLEEP
How Sleep Works
At Sleep Happy Products, we aim to help people discover those special finds of great sleep products that can actually improve your sleep.
A GOOD NIGHT'S SLEEP ISN'T A LUXURY.
IT'S A SCIENCE
Sleep is one of the pillars of living a healthy and successful life. You spend over a third of your life sleeping and in this section, you'll learn the science behind sleep, including what happens to your body while sleeping and why you need it, different types of sleep, and how much sleep you need.
BENEFITS OF SLEEP
"Even if you have a relaxed day with no significant exercise or mental work, you still need to get sleep"
How Sleep Works and its Benefits:
Learning – Your brain consolidates memories during sleep and you need a good night's sleep to really learn something. Memories are transferred from short-term to long-term storage during sleep and both factual knowledge and physical skills are learned in conjunction with sleep.
Creativity is also enhanced by sleep. Not just for artists, but people in general can come up with better ideas after a night’s sleep and with adequate sleep. You can think harder and more clearly when rested. People also are in better moods after a good night’s sleep and sleep deprivation makes you grumpy. The effect on mood is not just due to our general tendency to feel better when we feel stronger. It has been shown that the changes in brain chemistry after sleeping are similar to changes after taking anti-depressant drugs.
Cardiovascular impacts – the downtime of sleep allows your muscles to get some serious rest, and that includes your heart. During non-REM sleep your heart rate and blood pressure drop. If you don’t get enough sleep, you experience less time in this relaxed state and over time are at a higher risk for stroke, angina, and heart attacks.
Insufficient sleep puts your body under stress and results in higher levels of stress hormones in the bloodstream. Chronic low-level stress is associated with atherosclerosis in the long run.
The immune system is stronger when we get regular sleep. Regular short sleep makes you more susceptible to infectious diseases. Cytokines are produced in spades during sleep. The effectiveness of the flu vaccine is lower when we get insufficient sleep.
Sleep duration is also connected with body weight. Indeed, there is speculation that the accelerated lifestyles of recent decades have resulted in less sleep which has contributed to increases in diabetes and obesity rates. During sleep the body produces the appetite suppressing hormone leptin. The counterpart in the hunger system, the appetite-increase hormone grehlin declines. This effect, plus the general decline in daytime energy use, tend to make us fatter.
Quality of Life - Insomnia reduces quality of life as measured by physical or psychological well-being tests and surveys. The social cost of insomnia are high.
If sleep is a skill and if we can take measure to improve our sleep, the question arises: what should you be aiming for? What sleep goals are worth pursuing?
We want sleep to be:
Come quickly after we get into bed or try to sleep
Uninterrupted – a rule of thumb is that sleep efficiency under 80% is considered poor.
Refreshing – leave us restored, both physically and mentally
Uplifting – leave us in a better mood
We want to minimize:
Sleep inertia – how fast it takes to wake up fully in the morning
Sleep latency – time taken to get to sleep when first
Number of middle-of-night awakenings
Length of awakenings
Discomfort – sweating, labored breathing, temporary paralysis
Sleep efficiency can be measured with polysomnography, or even an EEG. An efficiency can be measured as a percentage (time spent asleep divided by time in bed).
CONSEQUENCES OF INADEQUATE SLEEP
Inadequate sleep leads to many social and physical problems for the individual and for the society he or she lives in. Primary (and a source of many social problems) is a reduction in cognitive function and vigilance. Response time to stimuli slows, the size of the working memory appears to decrease, the ability to learn is compromised, and creative thinking becomes more difficult as the ability for divergent thinking deteriorates. Not only do jobs and tasks require quick reaction times (e.g. driving) see a downturn in performance, so do more subtle cerebral jobs involving judgement and creativity. We are not as smart as individuals when we are sleep deprived and society suffers, too.
Sleep loss interferes with all manner of daytime functioning.
People who have been deprived of sleep (ether partial deprivation or total deprivation) are susceptible to involuntary episodes of microsleep, and even when not experiencing microsleeps have less vigilance, give less attention to tasks requiring brainpower, and show an increased number of errors when tested on cognitive tasks.
People suffering from partial sleep deprivation suffer from poor mood and a decline in cognitive function.
If you don’t get enough sleep you are more apt to catch a cold, And are more apt to become obese.
In the long run, people with who run chronically low on sleep are more likely to get diabetes. And increases the severity of metabolic disorders commonly associated with aging, e.g. metabolic disorder. Plus people suffering from inadequate sleep feel pain more acutely and perceive their general health as poorer than well rested people.
Unaware of their cognitive handicap - Chronic sleep restriction (not letting people sleep enough) over time leads to “cumulative, dose-dependent deterioration of attention and reaction time” Sometime people can do short, defined tasks well but performance deteriorates as tasks duration increases.
In controlled studies psychologists saw these declines in performance, and interestingly, the subjects seemed unaware of their handicap. They did not know they were having problems.
Accidents, the workplace, and driving - Drowsy driving is so bad we have a section of the Tuck website about it. Industrial accidents are more frequent when workers are tired. Drowsy driving accidents are often more serious than other wrecks because they often occur on high speed highways (because the driver is maintaining the same speed for a long period of time), there is no attempt to avoid the crash since the driver’s eyes are closed, and the driver is usually alone with no one to alert him or her. Long-haul truck drivers sometimes break the rules and sleep only two to four hours per night. Sleep deprivation has been shown to reduce the ability to make good split-second decisions that are needed in many jobs.
Shift workers are especially vulnerable to sleep deprivation. An alarming increase in the frequency of accidents happens during the graveyard shift. Notable incidents that have been due in part to sleep deprivation include the Exxon Valdez oil spill and Three Mile Island accident. Shift workers are also at particular risk for drowsy driving automobile accidents when driving home.
When workers have been sleep deprived their productivity drops and their risk for being party to an accident on the job increases. Fatigue and sleep deficit are known to increase the odds of a mishap. Most of the time these mishaps do not injure anyone, but some do.
A large scale study in The Netherlands showed the connection. This study was notable for the integrity of its construction. Workers were selected to be followed by researchers before any accidents occurred, The workers’ sleep habits and patterns were examined. That way, there was no way a person involved with an accident could mis-report good or poor sleep before an accident.
The role of fatigue and drowsiness in workplace accidents is no secret. It’s known in industrial hygiene, safety, and human resources circles. And the workers often know they are at risk.
Other researchers estimate those with insomnia are 2.5 to 4.5 times more likely to have an accident than those without.
Does it make you crazy?
No, sleep deprivation does not make people mentally ill in any meaningful sense. Insomnia is a very common symptom of many mental illnesses, so confusion occasionally arises about cause and effect. But sleep researchers do not feel that sleep deprivation causes psychosis or schizophrenia or depression or similar problems.
“Visual misperceptions” happen to sleepy people, but these are not the same as hallucinations or waking dreams. Auditory hallucinations are not experienced by sleep deprived people.
Sleep deprivation in children - Sleep deprivation is particularly a problem for children. In studies of elementary aged children, nearly 40% had some type of sleep problem, 15% exhibited bedtime resistance and 10% had daytime sleepiness. Nearly half of teens reported at least occasional difficulty in falling or staying asleep and almost 13% experiencing chronic and severe insomnia. This lack of sleep greatly affects mood, behavior, and academic performance. In pediatric research, poor sleepers reported being significantly more depressed and were even more likely to have a negative self-image. They were also more likely to exhibit type A behavior patterns and inferior coping behaviors and have more behavioral problems at home and in school. One study showed that students that students with C’s, D’s and F’s went to bed an average of 40 minutes later and got 20 minutes less sleep than A students. Insufficient sleep has also been associated with Attention Deficit Hyperactivity Disorder (ADHD), lower social skills and learning difficulties.
Are you and your family sleep-deprived? Sleep clinics measure sleep debt through use of a sleep latency test, which measures how easily someone can fall asleep. When this test is performed several times in a day it is called a multiple sleep latency test.
However, there are ways to tell if you are sleep-deprived without going to a sleep clinic. Experts say that needing an alarm clock in order to wake up is a sign that you are sleep deprived. Another is falling asleep within five minutes of your head hitting the pillow unlike well-rested people who tend to nod off after 10 to 15 minutes. Napping easily is a third sign.
With children, it is important to remember that they will rarely complain of sleep problems. Also, parents are often unaware of how long it takes their children to fall asleep and how often they awake during the night. Therefore, it is important to talk with their children about how well they sleep and monitor them for signs of sleep deprivation.
Sleep deprivation as a form of torture or as an interrogation technique
Law enforcement professionals sometimes employ forced sleep deprivation to get prisoners to talk – the idea being that tired people have lower resistance to truth telling. It’s hard to lie when you’re sleepy. The United Nations considers such tactics a form of torture.
This is one reason it is difficult to get data on the effects of sleep deprivation on humans and conclusions must be based on animal experiments or indirect observations. Ethical scientists cannot torture human subjects even if the subjects give their permission.
More nefarious techniques such as attempts to “brain wash” prisoners also employ sleep deprivation.
Deep sleep is the most refreshing sleep, as subjectively described by people after they wake up. Unfortunately, the older we get the less deep sleep we get.
Deep sleep is stage 3 sleep (or stages 3 and 4 under the classification that includes a stage 4). On an EGG the voltage difference patterns over time show up as delta waves. This is also called slow-wave sleep to distinguish it from the fast-wave sleep of Stage 2. Deep, or heavy sleep, is so-called because it is more difficult to awaken people in this stage than in light sleep, and if woken suddenly from this stage, people have sleep inertia. People in deep sleep are less apt to wake in response to external stimuli than those in light sleep Sleepers in deep sleep move their bodies less than in light sleep, although more than in REM sleep. The restlessness of some sleepers that results in tangled-up bedding occurs in light sleep.
Deep sleep is a time of accelerated tissue repair. In growing children, this is a time of physical growth. Human growth hormone is released in the first deep sleep episode of the night, and the period is associated with rejuvenation. Common childhood sleep disorders such as nocturnal enuresis, night terrors, and sleepwalking happen during this period.
At some level, we crave deep sleep more than other types. If you stay up all night and go about your normal activities the next day, you have some sleep debt. But if allowed to sleep the following night as much as you need to feel refreshed, you will probably not double the time of your normal sleep. Rather, the normal sleep time is appended with an additional one-third to one-half of normal sleep period. So someone who normally sleeps 7 hours per night, may, after a missed night’s sleep, go for 10 hours before feeling back to normal. The interesting thing is the distribution of time among the stages during this recovery sleep. Pretty much all the lost deep sleep is recovered. The amount of deep sleep during this second night is twice what it is in a normal night. Lengths of REM and light sleep are lower. It seems that the body chooses to conserve slow-wave sleep as much as possible, and it more willing to sacrifice other stages of sleep.
An interesting experiment showed this desire for deep sleep bubbling up to the surface of waking behavior, however subconscious. Scientists monitored the sleep architectures of people with insomnia over an extended period of time. The insomniacs were not given access to their EEG results. The insomniacs were also given access to sleeping pills (benzodiazepines) and told they could take them if they felt they needed to. After nights when the people had lesser deep sleep, the subjects were more likely to choose to self-administer the sleeping pills. Stage 3 length was the single most important factor in predicting whether pills were taken. This suggests people have a feeling about their need for deep sleep.
Getting Better Deep Sleep
How can you get more deep sleep? Unfortunately deep sleep can be elusive, and there is no way to directly force your brain to spend more time in this stage. The best you can do is prepare the ground for it and hope you will be blessed.
One way to prepare the ground is to get a full night’s sleep every night. Sleep medications can help, but remember that all sleep medications modify your normal sleep architecture. None directly lead to more slow-wave sleep pe se. They tend to result in increased time in light sleep, but light sleep might lead to deep sleep. Exercise, particularly strenuous anaerobic exercise such as lifting weights, may provoke more slow-wave sleep, although the evidence on this is not firm. It is probable that some people react to exercise by getting more deep sleep and others do not. The fact that tissue repair is at its fastest in deep sleep and human growth hormone release peaks during this stage cannot be overlooked. Aerobic exercise helps some people increase the length of time in deep sleep. There is some evidence that raising the body temperature, such as by soaking in a hot tub, increases predilection for stage 3 sleep. The effect of the aerobic exercise may be due to that fact that it raises body temperature. There are problems with this theory, including the fact that people tend to sleep better in cooler temperatures, stage 3 does not start until more than an hour after sleep onset during which time the body cools.
Is some stage 3 sleep deeper than others? Maybe. Generally, deep sleep or heavy sleep is called that only in comparison to light sleep. There is some physiological evidence that the “depth” of the sleep varies while the sleeper is in Stage 3. Monitoring of the brain can show instantaneous depth of sleep within Stage 3,
However, it should be emphasized that this variation is measurable only within one person. It is true that some individuals appear to sleep deeper than others in the sense that they are less apt to be woken by external stimuli, but there is no way to tell if any given person’s sleep is deeper or shallower per say than others.
The loss of deep sleep with age
One of the unfortunate effects of age is that as we get older we spend less time in deep sleep. While healthy people in their 20s spend 20% of the night in Stage 3, a typical 40 or 50 year old spends only 10% in that stage. By age 70 or 80, it is down to less than 5%, and sometimes maybe 2%. Other factors notwithstanding, you could look at a person’s EEG chart for a night and get an estimate of how old they are.
Why is this decline unfortunate? Less deep sleep is not just a result of aging; it appears to at least partially cause some of the negative characteristics of old age. Weakness, decreased mental acuity, infrequent feeling of refreshment in the morning – these are all connected to less deep sleep.
Sound Sleep or Deep Sleep?
What does it mean to “sleep soundly”? What does it mean to “sleep deep”?
We can unpack these phrases with the scientific discoveries about sleep physiology of the past several decades.
“Sound” means whole and possessing integrity. Sound sleep is a description given to a night’s sleep that is satisfying to the sleeper. This is subjective, of course, and probably in relation to the sleeper’s experience of recent sleep. A sound sleep for a 50-year old might be described as troubling by a 20-year old. And that’s a good word for the opposite: troubling. The opposite of sound sleep is troubled sleep.
If we were to hook up a polysomnography machine to a person getting sound sleep, we would see few nighttime awakenings, no significant breathing problems, and a decent amount of time spent in both slow-wave deep sleep and REM sleep. “Decent amount” is subjective, but we can ballpark it as 90 to 120 min per night of deep sleep and 90 to 130 min per night of REM sleep for adults. (Too much REM is associated with depression. There doesn’t seem to be any such thing as too much deep sleep.) Sound also somewhat tangentially refers to the depth of sleep and how susceptible the sleeper is to awakening by noise. This concept is probably close to what people mean by sleep deeply.
HOW LIGHT AFFECTS YOUR SLEEP
Light has a profound effect on our sleep and waking. Humans are diurnal, which means we evolved to sleep at night. Despite what some people may claim about their personal habits, it is easier to sleep in the dark than in the light, thanks to something known as your circadian cycle.
The circadian cycle
External environmental and social cues set the phase for the circadian cycle. The most powerful cue is daylight. Sunrise, high noon, and sunset are milestones in nature’s clock – a clock that encompasses and influences plants, animals, and human society. The ganglion cells in the eyes’ retinas are connected directly to the suprachiasmatic nucleus (SCN), the “master clock” for the body.
Light is so important in establishing the circadian time that it is safe to say that it swamps all other signals. When people get jet lag, the “cure” is getting used to the local time, and the best way to accomplish that is by spending time outdoors in natural sunlight.
Light exposure can have profound effects on sleep. When the environment transitions from darkness to light, our brains tend to wake, whether we have had our regular sleep or not. It is harder to sleep in bright light than dim light. But exposure to bright light during the day also makes sleep feel deeper and more satisfying the next night.
Your circadian clock dictates much more than just your sleep patterns. It also impacts many of your internal functions from other body organs, including appetite, cell regeneration, and brain activity.
Circadian rhythm disorders
When the body’s internal biological comes out of synch with the external environment, it can develop into a circadian rhythm sleep disorder. The disorder may result from a temporary condition (such as jet lag), a job (as with shift work sleep disorder), or a biological condition such as blindness (which corresponds with free running circadian disorder).
People with circadian rythm desorder experience insomnia, excessive daytime sleepiness, and unusual sleep patterns that interfere with their life and relationships, and their cognitive performance. Co-morbid conditions include depression and hyperactivity.
How light affects sleep
Exposure to light during the day keeps your energy levels up and improves your mood and cognitive performance.
People perform better on cognitive and physical tasks when it is light than when it is dark, independent of whether they feel sleepy. Just one hour a day of bright light has been shown to create these effects.
Evidence of brain imaging indicates that the waking brain is more active when the ambient light is bright. Even if we are not conscious of it and even if we find bright light distracting, we are more mentally nimble in bright light. Folk wisdom has long held that sunshine makes you happy, and indeed formal psychological testing has found positive effects from daylight.
Exposure to light during the day also helps you fall asleep at night, since your body recognizes the contrast with darkness in the evening and signals melatonin production to start.
The midday light exposure also increases the release of melatonin at night. The circadian phase doesn’t shift, providing a biochemical basis for the claim that being outdoors during the day can help you fall asleep at night.
A study of people working on office building found those in windowless environments tended to have lower scores on sleep quality tests than those who got to see the sun during the workday.
Night shift work and exposure to light at night has been linked to breast cancer, heart disease, obesity, and prostate cancer. The culprit may be that light reduces melatonin production – the hormone key to regulating your sleep-wake cycle.
Importance of darkness for sleep
Light signals to the body that it should be awake. On the other hand, darkness signals that it’s time to sleep. Often referred to as the sleep hormone, melatonin is also known as the darkness hormone, since its production coincides with darkness. Your brain begins releasing melatonin a few hours before you go to bed, reaching its peak in the middle of the night.
SHORT SLEEP AND RISKS
It has long been known that mortality rates vary with sleep times. Epidemiological studies have found that long sleepers have higher death rates than regular sleepers, and short sleepers also have higher death rates. Scientists who study this question arbitrarily set the definition of short sleeping as either 5 or 6 hours per night, on a regular basis.
Researchers at Penn State University did a long term study on people with “insomnia with objective short sleep duration” and found they were at higher risk for hypertension and diabetes and that the mortality risk in men, more than women, was greater in those who slept less than 6 hours per night.
Just considering men, the results of the Penn State study show that normal sleep times are correlated with the lowest mortality risk. In order of increasing risk:
normal sleep duration and no insomnia
normal sleep duration with insomnia
short sleep duration with no insomnia
short sleep duration with insomnia
In their statistical analysis, the Penn State researchers tried to separate out the effects of hypertension and diabetes and found that people in the fourth category, short sleep duration with insomnia, still had a significantly higher mortality risk. There must be something else going on besides hypertension and diabetes.
Oddly, the Penn State researchers found a minor, but statistically insignificant increase in mortality in women who were short sleepers. Why there is a difference between the sexes is not clear.
Further, the researchers concluded that after they adjusted for age, apnea, depression, obesity, alcohol use, smoking, and depression, there was still a correlation between short sleeping and early death. The authors concluded that for short sleepers, the increased risk of death from insomnia was comparable to the increased risk from sleep-disordered breathing.
Other researchers found that people with primary insomnia tend to have high levels of interleukin 6 in their blood, which may indicate either a problem in the immune system or a reaction by the immune system.
A Plethora of Health Problems
Other studies have found a relationship between short sleep and insomnia with hypertension And presence of inflammation makers in the blood The immune system and sleep have a complex, but tight, relationship.
It has also been found that adults in the 30-45 age range are more likely to have metabolic syndrome (a combination of high blood pressure, cholesterol problems, and high body mass index) if they are short sleepers.
Short sleep is also associated with reduced cognitive function in middle age and older people.
Young adults are much less likely to die from any cause than old people, but there are markers we can examine to see what the effects of short sleep are. And it has been found that short sleep in young adults is associated with lower general health (self-reported). Long sleep does not appear to be a danger in young adults.
Young adults are more likely to push themselves to sleep less than they need, so there is always more of a question with that age group than others. A small study found that short sleepers carry a greater sleep debt, suggesting these individuals may be imposing self sleep restriction.
Short sleepers are more likely to eat a carbohydrate-rich diet.
And the relationship between sleep and obesity is detailed here.
Longitudinal studies have found short sleepers are more likely to develop Type II diabetes. Short sleep in very young (pre-school) children is often an indicator of future obesity problems. Daytime napping does not appear to compensate for the reduced sleep at night.
Long Nights and Short
Both short and long duration of sleep are significant predictors of death. There is a U-shaped association, with 7 to 8 hours per night appearing to have the lowest mortality.
Work and short sleep
Shift-work sleep disorders is a recognized condition that affects people who work odd hours and can result in diminished sleep times. Workaholism is known to negatively affect sleep time and quality. This brings up the question of which job categories are most associated with short sleep. Analysis of available found managers were most likely to have short sleep, followed by workers in the transportation/warehousing and manufacturing industries. Is this because these jobs attract people who tend to sleep less or because of the effect of the job on the individual? Probably both. High mental-energy people may be more likely to be hired into managerial positions, and are also more likely to sleep less. Transportation workers includes truck drivers, which is somewhat worrisome given the dangers of drowsy driving.
WHY WE SLEEP
There are three kinds of sleep: light sleep, deep sleep, and REM sleep. Important physiological functions happen in all three – there is no wasted junk sleep in a healthy night’s sleep. Most middle-aged and older adults would probably prefer to get more deep sleep and less light sleep. A common shift in sleep architecture as we age is a loss of deep sleep and its replacement with light sleep.
One model that is useful is to think of two sleep systems in your body. They must both be asleep for you to be in deep sleep.
Children easily drift into deep sleep. The phrase “sleeping like a baby” more or less refers to a period rich in deep sleep. This is a period of growth and renewal for the body. Even adults experience a surge in growth hormone during their first deep sleep period of the night.
If there is any type of sleep that most middle-aged and older adults crave more of, it is deep sleep. As we pass from young adulthood to middle age, we get less deep sleep and more light sleep. Intuitively, we want more deep sleep and in the morning describe the previous night’s sleep as a good one if it included a lot of deep sleep.
Scientists have yet to determine exactly why people sleep. However, they do know that humans must sleep and, in fact, people can survive longer without food than without sleep. Sleep serves many functions – or more precisely, many things happen while we are asleep.
Scientists have floated many hypotheses on why humans require sleep:
The brain is able to reorder without the inputs it gets while awake. The brain has a chance to exercise important neuronal connections that might otherwise deteriorate due to lack of activity.
Sleep gives the brain an opportunity to reorganize data to help find a solution to problem, process newly learned information and organize and archive memories.
Sleep is a time for serious rest. Sleep lowers a person’s metabolic rate and energy consumption. The allostatic load on the body takes a toll and sleep is a respite.
The cardiovascular system also gets a break during sleep. Researchers have found that people with normal or high blood pressure experience a 20 to 30% reduction in blood pressure and 10 to 20% reduction in heart rate.
During sleep, the body has a chance to replace chemicals and repair muscles, other tissues and aging or dead cells. Growth hormones are released during deep sleep.
What is the function of sleep? There is no single purpose. The body does many things in during sleep.
Rebecca Reh at Harvard University posits four possible reasons for sleep:
Recovery – rest for the body, cell growth, housekeeping for body
Protection – keeping quiet and still reduces risk from predators
Energy regulation – use less energy when asleep
Memory consolidation – formation of long-term memories and learning
These are high-level reasons. Even this list is too-high level to be of much use in really understanding sleep.
It is a framework, but the details have yet to be filled in.
Caltech professor David Prober enumerates four hypothesis.
Repair of cell damage caused by life. Small animals with high metabolism sleep much of the day. Large herbivores can get by with only a few hours of sleep a day.
Rest. Long period of intense rest. The body’s energy reserves are replenished.
Brain and memory reorganization. Synapses are pruned and cleared. That’s why we wake up feeling refreshed and possibly more optimistic.
Reinforcing memory and learning that were formed during the day.
Whatever the functions are, it is safe to say that NREM and REM sleep have different functions, because they are so different. The characteristic “brain waves” – the EEG readings – are substantially different. REM sleep waves look like waking brain waves (there are minor differences). The skeletal muscles are paralyzed during REM; sleepers can move around during NREM. Memory consolidation and growth hormone release happen in earnest during NREM. Complex cinematic dreams happen in REM. Thermoregulation of the body happens in NREM but not in REM.
"Sleepiness"cannot easily be quantified although there are tests that can be useful in getting some grip on it. Four common tests are used to measure and quantify effects of stimulants and symptoms of disorders.
Multiple sleep latency test (MSLT) – time to get to sleep
Maintenance of Wakefulness Test (MWT) – time to get to sleep
Wilkinson addition test – cognitive test
Digital symbol substitution – cognitive test
provides some guidance as to why people get sleepy – duration of prior waking and place in the circadian cycle.
People describe themselves as feeling “refreshed” after sleep, as if their mental fuel tank has been recharged. But it is not clear at a biochemical level what this refreshment means. The brain uses plenty of energy during sleep, so sleep is not analogous to resting a muscle and allowing energy stores to recharge.
Sleep is about cycles. We run through the stages one after another. Waking (stage 0) transitions to NREM sleep – stage 1 followed by stage 2 followed by stage 3 followed by REM sleep (stage R) After REM the brain may briefly wake (maybe for less than a minute) or go directly to stage 1 again. Each cycle lasts about 90 minutes. Deep stage 3 sleep may disappear in the later cycles – when the brain has recovered from its need for deep sleep.
Education About the Importance of Sleep
We know sleep helps with education – a well-rested brain can more readily learn – but what about education about sleep.
Does it work? Does telling people about the importance of sleep, instructions for sleep hygiene, the symptoms of sleep disorders, and the good and bad points of treatments help them understand? How much is getting through and what can we do better?
This question is of interest to public health officials, parents and teachers of children and teens, and even us.