Sleep Training System™
Simple, common sense solutions
In this section we'll provide a scientific framework for understanding the surprisingly dynamic process of sleep. Knowing empirical, proven facts about sleep will help you feel more relaxed and confident about working with and improving your own sleep system.
You can’t not sleep.
Like food, water, the air you breathe – sleep is a necessity of life.
Sure, you can put it off if you like. You can stay up late and get up early if you want. You can drink coffee or pop pills to help stay awake. You can choose to burn the candle at both ends ... for awhile.
But eventually it will catch up to you. You can’t avoid it. At some point you must – and you will – sleep.
Your body and mind require it.
Your body’s physiological requirement for sleep is stronger than your insomnia.
Let’s repeat that for emphasis: Your body's physiological requirement for sleep is stronger than your insomnia.
The irresistibility of sleep is one cornerstone of the Sleep Training System. This is one key reason why, when properly applied, you can expect this program to work for you.
We will leverage this fact – that you can’t not sleep – to help break the back of insomnia. We will use this fact to in effect press the reset button on your internal sleep clock, your sleep system, and give you a fresh new start. This will help you shake loose whatever hold insomnia has, so that you sleep better and awaken more refreshed. Using the tools and techniques in the STS, you can and will sleep better, permanently, and without the need for sleeping pills or drugs of any kind.
The sleep paradox
It’s something of a paradox. Try as we might, we can’t directly control, force or will ourselves to sleep. That tactic usually backfires as one becomes overly worried, tense, and even consumed by the thought of not sleeping. A frontal assault just doesn’t work.
But what we can do is create conditions – both internal and external – that are conducive to sleep, and thereby control it indirectly.
In the STS, you’ll learn how to maximize control over your environment, behaviors, and your thoughts to enable optimal sleeping.
What is insomnia?
Insomnia is, simply put, the inability to fall asleep when desired and/or the inability to stay asleep for the desired amount of time; it may be a varying combination of the two. To be considered true insomnia, the sleeplessness must also be accompanied by an adverse affect on performance during one’s waking hours.
That last point is important. In other words, if you feel like you’re losing sleep but still perform just fine when awake, you may not have insomnia. If you think you might have insomnia but feel no grogginess, fatigue, or irritability when awake, then you may just need less sleep than you think you need.
That said, however, insomnia is still a very common condition. Those that do suffer problems stemming from an inability to sleep might take some solace in this fact: the majority of us describe symptoms of insomnia at some point in our lives.
In fact, a poll by the National Sleep Foundation found 58% of adults in the U.S. experienced symptoms of insomnia a few nights a week or more. The Centers for Disease Control (CDC) reports more than a third of Americans are not getting enough sleep on a regular basis. Another comprehensive survey found less than half of adults worldwide are sleeping well every night.
Of those reporting trouble sleeping, half suffer chronic regular insomnia that can last for years or even decades. Left untreated, chronic insomniacs may almost forget what a good night’s sleep feels like. Sleeplessness, restlessness, fatigue become the norm.
This doesn’t have to be you! The STS will show you how to naturally improve and powerfully strengthen your sleep system to the point where you stand a good chance of becoming a normal sleeper again.
Types of insomnia
Sleep scientists recognize two major types of insomnia.
Primary insomnia refers to sleep problems not caused by a physiologic or psychiatric disorder. In the STS, we may refer to this as common insomnia, learned insomnia, conditioned insomnia, or evolved insomnia. These broad terms in the STS all describe the same basic condition: sleeping problems with no apparent medical or psychiatric basis.
Millions of people have a form of primary insomnia that is often characterized by excessive worry about sleep. Known as psychophysiological insomnia, this condition is relatively common. Although reliable survey data is limited, the Institute of Medicine estimates some 30 million Americans, or roughly one out of ten persons, may have some form of psychophysiological insomnia.
It’s very important to understand that primary insomnia is often associated with some underlying issue – psychological, behavioral, or physical – that does not have a true medical or psychiatric basis. To effectively address primary insomnia therefore requires getting to the root causes that are not medical or psychiatric – something that sleeping pills can’t do. Identifying, understanding, and constructively addressing these root causes are focal points of the STS.
Comorbid insomnia, sometimes known as secondary insomnia, refers to sleeping problems associated with medical or psychiatric issues.
Restless leg syndrome, arthritis, back pain, and obstructive sleep apnea are examples of medical issues that can be connected to sleep problems.
Psychiatric issues associated with insomnia include depression, bipolar disorder, and substance abuse disorders.
According to the American Academy of Sleep Medicine, surveys suggest that approximately 3% of the general population has insomnia due to medical or psychiatric conditions. This percentage represents a relatively small minority of all people with sleeping problems. However, determining whether or not there are any accompanying issues to be addressed is one of the most important reasons to see your doctor before starting the STS.
In order to successfully treat comorbid forms of insomnia, the associated medical or psychiatric issues must be addressed with a health care professional.
How primary insomnia may evolve in normal sleepers
The vast majority of us experience a short term problem with sleeping at some point in our lives. This typically results from a stressful experience – a problem with a relationship, loss of a loved one, jobs, money, health, or a host of other everyday problems we all face.
For most people, short-term insomnia diminishes over time as the problem is either resolved or we adapt to it in some way. Sleep disturbances fade away completely and our natural sleep system recovers back to normal functioning.
However, for some of us, short term insomnia can evolve into a primary concern about sleeping independent of the problem that originally caused it. In other words, worry about sleep replaces the original source of stress. Sleep itself becomes the stressor. When that happens, insomnia can be perpetuated by a more or less constant stream of worry. This is how short term insomnia evolves into primary insomnia for many otherwise normal people.
When worry about sleep becomes excessive, a number of unintended consequences may occur. Bed time begins to be associated with dread. Thoughts like “Oh no, here we go again, another night of tossing and turning” become automatically connected, subconsciously, with the idea of sleeping. Just the sight of bed triggers worry. The thought of sleeping becomes a concern, a source of stress.
Once worry about sleep becomes a problem in and of itself, many people inadvertently respond in ways that only worsen their ability to get a good night’s sleep.
Such common counterproductive behaviors include:
- Drinking alcohol before bed to get drowsy.
- Cutting back or eliminating exercise due to fatigue from sleeplessness.
- Trying to force sleep and instead lying awake tossing and turning in frustration.
- Compulsively checking the clock, hour after hour, night after night, to see how much time it’s taking to fall asleep, or fall back asleep, and feeling all the worse because of it.
- Spending more time in bed, especially on weekends, trying to catch up on lost sleep.
Any of these sound familiar? None of these behaviors really help, and in fact probably worsen the problem. To successfully and permanently treat evolved or learned insomnia, you’ve got to get to the true roots of the problem.
The root causes for learned insomnia often are negative thoughts and maladaptive behaviors that undermine a good night’s sleep.
The best way to successfully treat learned insomnia is to treat not the symptoms, the sleeplessness itself, but to get at the root causes – which commonly are negative, self-limiting thoughts and counterproductive behaviors that disrupt sleep.
For many of us the solution is not that complicated. Literally tens of millions of us have some form of primary insomnia, often unintentionally caused by negative thoughts and behaviors that undermine sleeping well.
Moreover, even in instances where insomnia is associated with a medical or psychiatric problem, there likely is considerable overlap with a conditioned or learned component that disrupts good sleeping.
Addressing these root causes is the focus of this program.
Using the STS, you will become more aware of and better understand these underlying thoughts and behaviors that interfere with sleep.
Working with proven principles to counter dysfunctional thoughts and behaviors, you will steadily strengthen your mind and body’s inherent natural sleep system. These methods have been shown to help most everyone in some form. Using these tools and techniques, many former insomniacs have become normal sleepers again.
Let’s turn now to some basic principles about sleep. This background knowledge will help you better understand sleep, possibly clear up some misconceptions, and help you begin to feel more confident about strengthening your own sleep system.
What is sleep?
Sleep is a naturally occurring state of deep rest. In humans, sleep is characterized by a disengagement of our conscious minds, and by muscle inactivity. All mammals, and most animals – including birds, reptiles, fish, even insects – need some form of sleep to survive.
The amount of sleep, when it occurs, and how it happens varies widely among different species. A brown bat, for instance, sleeps about 83% of its life, while a giraffe sleeps less than 2 hours a day.
Species Average Total Sleep Time (hours/day)
brown bat 19.9
owl monkey 17.0
human infant 16.0
bottlenose dolphin 10.4
guinea pig 9.4
human adolescent 9.0
human adult 8.0
National Institutes of Health
Some animals have evolved remarkable adaptations to be able to sleep and survive in an otherwise inhospitable environment. Consider advanced mammals like dolphins and whales for instance. How do they sleep and not drown?
These animals have developed the truly amazing capability of unihemispheric sleep, in which one side of the brain sleeps while the other side is awake. Unihemispheric sleep allows dolphins and whales to sleep on one side of their brain while the other side stays alert. This enables them to continue swimming and surfacing to breathe while part of their brain sleeps.
Birds that make long transoceanic or migratory flights, such as mallards, do the same thing – sleep on one side of their brain, then switch to the other. This capability allows these animals to sleep while simultaneously tracking other group members and watching for predators.
Interestingly, some research suggests humans may have also a vestige of this capability, which might help explain the so-called “first night effect”. This refers to the tendency some of us have to sleep poorly the first night we are away from our normal bedroom environment. This research shows during the first night’s sleep away from home one hemisphere of our brain may have some limited response to external noises, while the other side does not. The research also showed on subsequent nights the unihemispheric response was reduced.
Many animals like dogs and cats are polyphasic sleepers, meaning they catch several naps throughout a 24-hour cycle, instead of having one unbroken phase of rest. Humans are typically monophasic sleepers, meaning our bodies and minds have over time adapted to sleep normally over one sustained time period.
Sleep is a dynamic process
Although characterized as a state of deep rest, neuroscientists using sophisticated measuring devices have shown there is much going on in our minds and bodies while we sleep.
We actually are in a dynamic state both physically and mentally while asleep. Electrical activity shifts within our brains, and various chemicals ebb and flow throughout our bodies. Key to this dynamic process are tiny structures in the brain that are sensitive to light and regulate our circadian rhythms.
Circadian rhythms – the cycles of day and night – control sleep to some degree in all living beings. The physiological mechanism that regulates sleep is sometimes referred to as the biological clock, and the surprisingly simple cue that synchronizes the internal biological clock to the environmental cycle is light.
Graphic: Yassine Mrabet
Idealized circadian rhythm of a person who rises early in the morning, eats lunch around noon, and goes to sleep around 10 p.m.
The specific neurological mechanisms by which light and dark regulate sleep are an ongoing subject of scientific study. The pineal gland appears to play an important role; this organ deep within the brain produces melatonin when it gets dark, and reduces melatonin levels when it gets light.
The body’s master biological clock is a tiny cell cluster in the brain called the suprachiasmatic nucleus, or SCN. The SCN responds to light, generating a “wake-up” cue to other structures located deep in the brain.
One such deep brain structure, the hypothalamus, is critical to sleep function by helping to regulate chemicals in our brains that promote both sleep and arousal.
Another structure called the thalamus helps us sleep by blocking input from our senses. The thalamus prevents us from waking up while sleeping – which in turn enables the brain to perform its critical function of reviewing and processing information from the day. The thalamus is impressively selective in what stimulation it blocks however; some people can sleep soundly through the roar of a freight train yet awaken to a baby’s cry.
National Institutes of Health
The biological clock is located within the suprachiasmatic nucleus in the brain, and is affected by light, as is the pineal gland. Note the near direct pathway along the optic nerve from the eyes to these structures in the brain.
The crucial role circadian rhythms, the biological clock, and light have for sleep functioning is confirmed by the experience of those with blindness. Most persons who are completely blind suffer from insomnia to some degree, because they cannot distinguish day from night. Their biological clocks cannot be reset by sunlight or any form of bright light for that matter. Blind persons are sometimes treated with doses of artificial melatonin to help regulate their natural circadian rhythms.
Although the exact function of melatonin in humans is not completely clear, this substance is sometimes prescribed for circadian rhythm disorders and as a “natural” treatment for insomnia, although evidence for its effectiveness in those with normal eyesight is inconclusive.
Our biological clocks change as we age
Ideally, our biological clock is synchronized closely to the daily 24-hour cycle of the sun. The reality is not that simple.
One factor is the constantly changing length of day and night throughout the year. Depending on your latitude and the season, there are wide variations in the amount of darkness or sunlight you experience each day, and the duration of daylight typically changes by several minutes for each successive 24-hour cycle. To compensate, our built-in clock constantly adjusts to the changing of the seasons, a process known as entrainment.
Another factor is normal human physiology. From about age 14 to 30, it's common for our biological clock to slow down significantly from a normal 24-hour circadian cycle. Adolescents and young adults may experience more of a 26 to 30 hour day. So for this age group, when 11 p.m. rolls around it may feel more like 7 or 8 p.m. This is why it's common for a teenager to be wide awake at a normal bedtime. And at 7 a.m., it may feel more like 3 or 4 in the morning. Hard to get up that early!
Fortunately, by about age 30 most of our biological clocks speed back up to a more normal 24-hour cycle.
Later in life, the biological clocks of some (not all) of us continue to speed up faster than a 24-hour cycle. So this is why 8 p.m. may feel more like 11 p.m. for someone in their 70s, and 4 a.m. may feel more like 7 a.m.
Another possible factor has to do with the gradual aging of the eye. The normal yellowing of the lens and the narrowing of the pupil that occur with age can potentially disturb the body’s circadian rhythm. To help produce better sleep, this condition can be countered by deliberate exposure to indirect sunlight.
Regardless of your age, one way to maintain or recalibrate your biological clock back to normal is to use a consistent wake-up time each day, every day without exception, as much as possible. Then upon awakening immediately expose yourself to light, preferably daylight. This consistency supports better sleep, and we will explain it in much more detail in the Sleep Timing and Sleep Hygiene sections.
Artificial lighting affects sleep
Human beings have today a unique technological advantage to adjust for the role of sunlight in natural circadian rhythms. Since the advent of widespread electrical utilities and the development of artificial lighting within the last century or so, we can today with the simple flick of a switch turn night into day within our living spaces. The control of abundant artificial light allows us to have a much greater ability to choose when we sleep, and when we stay awake.
Prior to the advent of widespread artificial lighting, at night people were completely dependent on the flames of relatively dim candles, lamps, and lanterns, and as a result were far more attuned to the cycles of the sun.
Today we are less dependent on sun-to-sun lighting cycles, although many scientific experiments have shown people are still genetically hard-wired and exquisitely attuned to the natural cycles of day-and-night throughout the seasons.
Nevertheless, we can exert far more control on our periods of sleep and wakefulness than could previous generations.
The ability to easily control sleep periods, by itself, can cause problems if any of a multitude of distractions crop up to interfere with sleep. However, the ability to control also creates powerful opportunities to address those distractions.
In the STS you will soon leverage these powerful opportunities to control – by learning how to create an optimal environment for restful, quality sleep.
Stages of Sleep
Sleep is far more than just an unconscious mental state. Sleep researchers have determined that several stages of sleep with varying amounts of physical and mental activity occur predictably each night. These stages of sleep have been extensively studied, and are divided into two main types –
Rapid Eye Movement (REM) sleep, and
Non-Rapid Eye Movement (NREM) sleep.
REM sleep is characterized by tiny back-and-forth movements in the eye, and typically are accompanied by the visual and emotional world of vivid dreams. The eyes move in tandem, as they do normally during an awakened state. The tiny muscles in our inner ears move as if we're hearing, even in complete silence. REM sleep typically comprises about 20-25% of sleep for most adults, although that percentage declines somewhat as we age. All of us dream, even though we may not remember the dreams.
REM sleep makes it appear as if we are watching and listening to what’s going on as we dream. Some scientists believe that the eye movements of REM sleep relate to the visual images of dreams, but why they exist and what function they serve, if any, remain unknown.
REM sleep includes very active brain activity, and if awakened during REM sleep many people will vividly remember their dreams. Our bodies are also much more active during REM sleep, with a higher heart rate, breathing, and blood pressure than during deep sleep. REM sleep is also characterized by a natural form of muscle paralysis, although this is the sleep phase when males often experience an erection, and females experience clitoral engorgement.
During REM sleep, a deep inner part of the brain known as the pons blocks signals from the brain to the spinal cord, resulting in a form of paralysis. Sleep scientists theorize that such muscle paralysis is necessary to keep us from physically acting out our dreams.
NREM sleep is generally associated less with vivid dreaming, although studies have shown some form of dreaming activity to be a continuous process during sleep. NREM sleep is often divided into 4 distinct stages that represent different states of body and brain activity while falling asleep and during deep sleep.
Stage 1 sleep is drowsiness. It typically lasts about 5 to 10 minutes. The eyes are closed, but if awakened a person probably would say he or she has not slept. One of the goals of the STS is to help you more easily drift into this first drowsy phase of sleep, which then sets the stage for true sleep.
Stage 2 is deeper than Stage 1 drowsiness and a form of true sleep. The heart rate slows, respiration becomes slower and deeper, and body temperature decreases as it gets ready for deep sleep. However, an external noise or disturbance would easily awaken us from this light form of sleep. Stage 2 sleep may last 30 to 45 minutes.
If at times you feel you are lying in bed but not sleeping, yet somehow the hours seem to go by quickly – you probably are in fact lightly sleeping in Stage 2 or deeper. Keep this in mind as you work the STS – Stage 2 sleep counts as legitimate sleep. It is serving its purpose of helping refresh and rejuvenate you for another day.
Stages 3 and 4 are deep sleep, sometimes called slow-wave sleep, characterized by deep slow breathing and regular continuous rhythms of brain activity. Stage 4 shows deeper patterns than stage 3. We are for the most part cut off from the stimulation of the external world in deep sleep, and least likely to be awakened by a noise or other disturbance at these stages. The deep sleep stages may last around 45 minutes or so.
After stage 4 is reached, stages 3 and 2 repeat, then a period of REM or dreaming sleep is attained. So a typical progression is 1-2-3-4-3-2--REM.
In a typical night, each of these sleep cycles lasts from 90 to 110 minutes on average. The first few cycles of the night typically include longer stages 3 and 4, meaning the deepest sleep, with less dreaming. Later in the night, the amount of REM sleep and vivid dreaming increases in each successive cycle. Typically a person will have four to six of these cycles each night, and the amount of REM dreaming on the final cycle will be around an hour. Why sleep occurs in such cycles in currently unknown.
National Institutes of Health
A typical night for a young, healthy adult, showing 5 cycles of REM and NREM sleep. Light gray areas represent non-rapid eye movement (NREM) sleep.
Clinical research suggests that deep sleep (Stages 3 and 4) is the most important stage, in that those that are sleep deprived first make up time spent in deep sleep. During deep sleep, blood flows primarily to the muscles and not the brain. It is during deep sleep that our physical bodies are replenished with energy, children grow, and our immune systems are most capable of fighting illness. Deep sleep also enables the brain to help clear itself of toxins.
The function of REM sleep is less understood, although research suggests both REM and NREM sleep help consolidate memory, facilitate learning, and help clear brain plaques associated with Alzheimer's disease. Neurological evidence also shows the limbic system -- those brain structures most responsible for the regulation and processing of emotions -- are more active during REM sleep stages. For most people, REM sleep may also help to in effect reset the emotional state, in that a lack of REM may result in one feeling more irritable or grouchy the next day.
More clues about the purpose of REM sleep come from biological studies of primates. Of all primates, humans sleep the least but have the highest percentage of REM.
Evolution, Medicine, & Public Health, 2016(1), 227-243
Of all primates, humans sleep the least but have the highest percentage of REM dream sleep.
In a simple way then, we might look at NREM or deep sleep resetting the physical body, and REM or dream sleep resetting the mind, and especially one's mood, for a new day.
As we age, the amount of time spent in deep sleep tends to decrease. This is normal. Older individuals will often enter REM sleep faster than younger people. This is but one change in sleep over time as we age.
The time between sleep cycles is important to understand
Because sleeping is lightest between cycles, it’s common for normal sleepers to briefly awaken the five or six times between cycles per night, and then fall back asleep within seconds. Typically these very brief periods of awakening are so short they are forgotten by morning.
Moreover, even the best sleepers will awaken to some degree at least 10 to 15 times per night and forget about it by morning. Finer indications of arousal, such as brain wave activity measured in a sleep lab, show that normal sleepers actually awaken some 10 times or more per hour on average, although these arousals typically last less than 15 seconds. Transient awakenings like these are benign, and by themselves nothing to worry about.
So if you do wake up in the middle of the night – and you’re not awakened by some external noise or disturbance – there’s a good chance you’ve just completed one of these natural sleep cycles. You may also remember a dream from a just completed REM stage.
These brief periods between cycles are an especially important time to understand. Because sleep tends to be lighter as we age, instead of falling back asleep quickly between cycles some people may move the other way – toward an increased level of wakefulness. It may then take longer than a few minutes to fall back asleep.
For insomniacs, these brief wake-ups, even though normal, can become a cause for concern. That concern can then feed on itself, developing into something more – a self-perpetuating negative cycle of worry. In other words, worrying about falling back asleep keeps you up.
In this way, concern about being up can automatically trigger a heightened state of worried wakefulness, rather than the kind of drowsy state (Stage 1) that would be more conducive to falling asleep.
This is another example of how insomnia can inadvertently evolve from a conditioned response or learned behavior. But just as it can be learned, it can be unlearned. Bad habits can be broken, just as good habits can be intentionally cultivated. These are areas of emphasis in the STS we will soon be covering.
In the STS, you will learn how to relax and fall asleep when you want. You will learn relaxation tools and techniques that enable you to more easily let go, quiet your mind, and thereby move naturally back toward Stage 1, a drowsy state more conducive to sleep.
These are some of the key principles we will focus on; but for now just understand why, especially as you age, it’s not uncommon to find yourself up during the brief periods between one or more of the several sleep cycles you experience each night.
Sleep and body temperature
Another interesting finding from sleep research is that body temperature drops about 2 degrees during sleep, and rises during waking hours. Contrary to popular belief, your body is not always 98.6 degrees.
National Institutes of Health
Body temperature normally drops about 2 degrees during sleep.
We are typically most alert when our body temperatures are highest, and most sleepy when our body temperatures begin to drop. This is one reason why a cool room is conducive to a better night’s sleep, and why night sweats or the inability to cool off is associated with difficulty sleeping.
The natural cooling we experience during sleep is often reduced as we age. While the body temperature of a healthy young adult may drop about two degrees during sleep, by age 75 some of us may experience a drop of only around a half degree.
This reduction in the amount of body cooling, combined with a faster than normal biological clock, can result in a significant flattening of the overall circadian rhythm as we age. For insomniacs, this flattening can be manifested by more awakenings during the night – characterized by lighter, more fragmented sleep – and by less alertness during normal waking hours – as characterized by more napping during the day.
So as we age there may be a tendency to spread out sleep more evenly over each 24-hour period, rather than having two sharply defined periods of sleep and waking.
There are a number of effective methods to counter this age-related tendency toward a flatter circadian rhythm. Doing so helps produce more robust sleep and supports greater alertness and energy during waking hours. These are worthy goals, and the STS will help you achieve them.
A cool room is just one of many ways you can help yourself sleep better. Using a disciplined sleep schedule, controlling negative sleep thoughts, reducing chronic stress, and creating an optimal sleeping environment all work together to help counter a flattening circadian rhythm and support better sleep. In the STS, we will examine all these topics in detail.
The biological pressure to sleep cannot be resisted
After about 16 hours of nonstop wakefulness, we normally feel a biological pressure to sleep. This pressure, known as the homeostatic sleep drive, is controlled by a separate neurological regulatory mechanism in addition to the biological clock.
This regulatory mechanism is keyed by a pinhead-size cluster of brain cells known as the ventrolateral preoptic nucleus, or VLPO. The VLPO is sensitive to a chemical naturally produced in the brain known as adenosine, one of several neurotransmitters involved with our daily sleep-wake cycle. After about 16 hours of adenosine build-up, the VLPO sends out a signal that it’s time to sleep.
In this way, the brain essentially keeps track of how long it is awake, and after about 16 hours reinforces the circadian rhythm to induce sleepiness. For optimal sleep, it's therefore important the two processes -- sleep drive and the biological clock -- are synchronized and working well together. Later in the STS, you will learn how to enhance this mutually supportive process that can make sleep when you want it practically irresistible.
As we age, the VLPO typically loses some of its neurons, and thus some of its ability to drive sleep. This is one reason why as we age we tend to experience lighter, more fragmented sleep. So some diminishment of the VLPO is therefore a normal consequence of aging, and this helps explain why the elderly often sleep less than younger adults.
To counter this natural age-related reduction of the VLPO, there are a number of simple, effective, completely drug-free methods you can use to strengthen and in effect rev up your sleep drive. We will cover this in the first week of the STS.
Interestingly, caffeine apparently disrupts the neurological homeostatic process by blocking the VLPO’s ability to recognize adenosine. So in addition to being a metabolic stimulant, this is another reason why caffeine can disrupt sleep.
Despite the unknowns however, this is a certainty: the longer an individual remains awake, the stronger the desire and need to sleep becomes.
We call this irresistible certainty the “Law of Prior Wakefulness”, and we will use this principle extensively in the STS.
There is no “normal” amount of sleep that’s right for everyone
Sleep, as a natural human phenomenon, is still not completely understood despite significant ongoing research. There is no one agreed-upon number experts use as the ideal amount of sleep for everyone to get.
However, determining the right amount of sleep for your own personal system is important because insufficient sleep has a number of negative consequences. A lack of sleep has been shown to negatively affect alertness, memory, problem solving, and overall health, as well as increase the risk of accidents. A 2003 study at the University of Pennsylvania School of Medicine demonstrated that cognitive performance declines with six or fewer hours of sleep. Other studies have shown that a lack of sleep increases cravings for especially fattening foods, and may contribute to obesity and diabetes.
The reverse is also true. Getting good sleep is considered an essential component of overall well being, enabling us to perform at our best during waking hours. Healthcare professionals recognize that quality sleep is a vital component of happiness, and is one of the best forms of preventive medicine.
So instead of a single number, sleep therapists generally recommend a range that is normal for most people. The National Sleep Foundation suggests that seven to nine hours of sleep for adults is optimal. A 2009 British study suggested consistently sleeping 6 to 8 hours per night may be best for health. Other studies have shown six to seven hours increase longevity.
A 2015 cross-cultural study found those living today in some of the world's few remaining preindustrial societies -- meaning hunter gatherer and subsistence farming groups without access to electric lighting or heated and cooled living spaces -- generally spend about 7 to 8.5 hours in bed. These people average about 6 to 7 hours actually sleeping per night, with very little evidence of insomnia or other negative consequences of sleep deprivation.
These observational studies suggest generalized ranges for healthy sleep duration, but on an individual level, each of us is different -- and every one of us has different sleep requirements.
Some people are genetically predisposed to need less sleep than others. A very small percentage, called short sleepers, function normally with 5 or less hours of sleep. Determining the right amount of sleep is also a moving target – it changes as you age.
Normal changes in total sleep and percentage of REM sleep over time
A century ago, before widespread artificial lighting, we slept longer during the winter when the days are short and nights are long, sometimes spending 10, 11, 12 or more hours in bed. There are widespread historical records showing normal sleep a century or more ago during the winter was more biphasic, with two blocks of sleep separated by two or more hours of wakefulness in the middle of the night.
Back then, people might sleep for four solid hours, wake up for two or more hours, then fall back asleep again until morning. The wakeful period in the middle of the night was called “the watch” or watchful sleep period. This was generally described as a period of quietness and peacefulness, almost like a meditative state.
So if in the night, and especially during long winter nights, you sometimes find yourself awake between cycles of sleep, remember you are only a few generations removed from when this was more of the norm.
In addition, as we age, the quality of deep sleep – the most restorative sleep characterized by deep brain waves – tends to be reduced, and sleep tends to become more fragmented. Most experts agree as we age we still need just as much sleep as when we were younger, but we are more likely to be disturbed by outside environmental factors, like a snoring partner or barking dog.
This means our inherent sleep system tends to naturally become a bit more fragile as we age. Sleep scientists are not sure exactly why this happens – one theory is that sleep is like many other physical abilities that normally tends to diminish in strength as we age. Despite this diminishment, however, many people self-report satisfaction with their sleep as they age.
Using the proven methods in the STS to strengthen your sleep system, there is every reason to believe that you too, like many others, can restore and maintain the quantity and quality of your sleep to your satisfaction as you age. And if you find you awaken more easily as you’ve gotten older, be assured this by itself is not some sort of inherent defect; rather it is considered normal and nothing to worry about.
Determining the right amount of sleep for you is a personal decision
There are many interrelated factors that determine how much sleep is best for you, including your unique metabolism, which changes as you age. Your sleep can be affected by your diet, your occupation, the amount of stress you experience on any particular day. Your sleep can be influenced by the amount of exercise you get, and many psychological factors we will soon consider in depth.
The bottom line? There is no one specific number of hours that is the “right” amount everyone should get. Instead, there is only one number we are concerned about: what’s right for you, and the STS will help you determine that.
As a starting point, if you believe that somewhere between 7 to 9 hours a night is right, you will most likely be on the right track. If you want to pick a target number as a starting point, we suggest 8 hours of sleep. Using the STS’ interactive Sleep Logs as a tool, you will be able to progressively adjust the amount of time you allow for sleep to best fit your own unique situation.
Now, with a factual and scientific basis for understanding the dynamics of sleep, we have a solid foundation for working with the STS.