This document describes some of the key facts about sleep, biological rhythms, and sleep deprivation that should be well known to every Stanford student as well as everyone everywhere. It will be occasionally updated.
A recent survey of Stanford undergraduates revealed that their number one complaint was not getting enough sleep! heard a validation of this complaint from the lips of a well known alumnus, Tiger Woods, who said that one of the best things about his choice to leave Stanford for the professional golf circuit was that he could now get enough sleep. Although I offer an undergraduate course on sleep and dreams once each year, it is clear that it does not meet the need for all students to have some information about this topic. Most entering students have previously received no teaching whatsoever about sleep. In contrast, nearly all entering students have received a great deal of information about two other health basics, nutrition and physical fitness.
Thus, an amazing paradox exists in our educational system. We have learned that the consequences of pervasive sleep deprivation and undiagnosed sleep disorders are collectively one of our nation's biggest and most serious problems. Falling asleep at the wheel and in other hazardous situations is a leading cause of death and disability. A single sleep disorder, obstructive sleep apnea, is now known to afflict 30 million Americans.
The paradox is that our society remains a vast reservoir of ignorance about sleep deprivation and sleep disorders. The benefits of the hard earned knowledge about normal and pathological sleep have not been passed on to the general public and practicing physicians. Millions of people are suffering and thousands are dying each year without ever knowing the true cause of their problems.
Why is this? Teaching about sleep and dreams, the nature and consequences of sleep deprivation, and common sleep disorder symptoms is essentially absent from the undergraduate and graduate curriculum in our colleges and universities. Perhaps the saddest omission of all is that most student drivers learn nothing about the dangers of driving drowsy in their training programs, and an astounding number soon die and kill others because they fall asleep at the wheel. Fifty-five percent of drowsy driving fatalities occur under the age of 25.
Although I am directing this message to entering freshman students at Stanford University, I am also striving to bring these topics into the mainstream of the national educational system. In every classroom in America, students must learn that healthy sleep, along with physical fitness and good nutrition, form the fundamental triumvirate of health. However healthy we think we are, students and non-students alike, we must realize that we cannot be healthy unless our sleep is healthy!
Each of us has a specific daily sleep requirement. The average sleep requirement for college students is well over eight hours, and the majority of students would fall within the range of this value plus or minus one hour. If this amount is not obtained, a sleep debt is created. All lost sleep accumulates progressively as a larger and larger sleep indebtedness. Furthermore, your sleep debt does not go away or spontaneously decrease. The only way to reduce your individual sleep debt is by obtaining extra sleep over and above your daily requirement.
The powerful brain mechanism that regulates the daily amount of sleep is called the sleep homeostat. By increasing the tendency to fall asleep progressively in direct proportion to the increasing size of the sleep debt, this homeostatic process ensures that most people will get the amount of sleep they need, or close to it. The elevated sleep tendency together with the associated drowsiness and an intense desire for sleep would ordinarily prevent most people from becoming dangerously sleep deprived because they would go to bed early, or sleep late, when such excessive daytime sleepiness occurred.
However, in our society we are prone to ignore or resist nature's signal that we need more sleep, and we often resist far too long. At this point, we cannot resist falling asleep. Depending on when and where this happens, falling asleep can be tragic, or merely inconvenient. As far as is currently known, nothing can change an individual's fundamental daily sleep requirement.
You can learn more about sleep debt (including funny videos made by college students who know all too well about it) at the Stanford Sleep and Dreams website.
To repeat, the size of your sleep debt determines the strength of the tendency or ability to fall asleep. If your sleep debt is zero, sleep is impossible. If your sleep debt is very low, only a small amount of stimulation is required to keep you awake. If your sleep debt is very large, no amount of stimulation can keep you awake.
Think of your sleep debt as a very heavy load. You are carrying with the help of two companions. Together, the three of you can hold it up. One of your companions is pretty strong. This companion is your biological clock. The other companion is not quite so strong, and represents transient external stimulation, e.g. noise, light, excitement, anger, pain, and so on. If one of your companions drops out, you and the other may be able to manage. If both companions drop out and you are left alone, you absolutely cannot hold up the heavy sleep debt and you are crushed. In other words, you cannot stay awake no matter how hard you try. Even without external stimulation, it is usually easy to stay awake and alert if your stronger companion, the biological clock, is helping you.
With the above image in mind, it should be clear that the things we usually assume cause us to become drowsy or to fall asleep actually do not cause us to become drowsy or to fall asleep. Their true role is to unmask any tendency to fall asleep that is present already. If you believe that boredom, a warm room, or a heavy meal causes sleep, you are completely wrong! If boredom, a warm room, or anything else seems to cause you to feel drowsy, you have a sleep debt and you need to be stimulated in order to stay awake. If you frequently feel sleepy or drowsy in any dull or sedentary situation, you almost certainly have a very large sleep debt. A large sleep debt makes us vulnerable to apathy, inattention, and unintended sleep episodes. Errors, accidents, injuries, deaths, and catastrophes can be the result, not to mention poor grades.
How many Americans are seriously or dangerously sleep deprived? There is no doubt whatsoever that vast numbers of us in school, in the workplace, in the transportation industry, in a variety of service industries, and particularly, in shift work situations, are carrying a dangerously large sleep debt.
In Gallup Poll surveys, 56% of the adult population reports that drowsiness in the daytime is a problem. In one scientific study where sleepiness was measured objectively in more than one thousand people who said they had no problem with daytime drowsiness, 34% were found to be dangerously sleepy. Considering that the subjects in this study were chosen specifically because they did not complain about daytime sleepiness, this result proves without a doubt that a significant percentage of the population carries out daily tasks and activities while dangerously sleepy.
Here at Stanford, we have studied samples of undergraduates, nurses, and medical students. We found that 80 percent were dangerously sleep deprived. By dangerously sleep deprived, I mean, of course, that these individuals are at high risk for some sort of accident involving unintended sleep or impaired performance. In all walks of life, it is likely that sleep deprivation has consequences - difficulty studying, diminished productivity, tendency to make mistakes, irritability, fatigue. For most people, the accumulation of a huge sleep debt appears to have happened so gradually that they erroneously blame their tiredness and fatigue on many other things such as a virus, depression, stress, changing metabolism, growing older, and so do their doctors.
The biological clock is a term applied to the brain process which causes us to have 24-hour fluctuations in body temperature, hormone secretion, and a host of other bodily activities. Its most important function is to foster the daily cycle of sleep and wakefulness. The major role of the biological clock in the regulation of sleep and wakefulness is to provide an internal and very powerful wake-up signal to the rest of the brain.
This powerful signal is called clock-dependent alerting, and when present, it powerfully opposes the tendency to fall asleep. In the absence of any other stimulation, the process of clock-dependent alerting alone can usually keep us wide awake throughout the entire day. This may not be true if we are carrying a fairly large sleep debt. In ordinary circumstances, clock-dependent alerting is always synchronized with the daytime hours. However, if we travel rapidly to other time zones, it may occur during the sleeping hours, and we experience "jet lag."
I sincerely hope that sleep deprived students will take the following advice very seriously. Drowsiness is red alert! Drowsiness is the last step before falling asleep, not the first. Imagine what that could mean when you're behind the wheel of a car driving on the highway. Drowsiness may mean you are seconds from a disaster. If everyone responded as if it were an emergency when they became aware of feeling drowsy, an enormous amount of human suffering and catastrophic events would be avoided.
You can learn more of why Drowsiness Is Red Alert from the students of Stanford Sleep and Dreams, with a little help even from the likes of Ray Ramano, John Elway, and Oprah Winfrey.
We should certainly define the basic biological state that we have been discussing. Most of the characteristics that people invoke to define sleep- immobility, eye closure, snoring- can be readily simulated in the waking state. We should ask then, what is the most fundamental difference between a human being awake and a human being asleep?
Answer: The crucial event that occurs as we fall asleep is an abrupt shut down of the neural processes that allow us to perceive the world around us. At one moment we are awake, and can see and hear. A fraction of a second later we are asleep, and we are completely blind and completely deaf. Another way of saying this is that sleep is a behavioral state of complete perceptual disengagement from the environment. Sleep is an active process in which sensory stimulation is blocked or modified in some way such that we cease to be conscious of the world around us. In fact, research over the past couple of decades has decisively established that the sleeping brain is an active brain. Because so many people believe that sleep occurs when the brain is "turned off," I like to say, "If that is your image of sleep, then hear this, 'the brain never sleeps!'"
Of course, there is much more to say about what sleep is and what the sleeping brain does, but not here. That would make this document far too long.
Sleep disorders are illnesses and disturbances of sleep and wakefulness that are caused by abnormalities existing only during sleep or abnormalities of specific sleep mechanisms. These abnormalities typically produce symptoms during wakefulness that are easily recognized if the person is aware of their significance, but the fundamental pathology exists during sleep. Though the symptoms that exist during wakefulness can be helpful in recognizing the possible existence of a sleep disorder, an absolute certainty generally requires an examination of the patient during sleep utilizing a procedure called polysomnography, also widely known as a "sleep test."
You can learn about all the various types of sleep disorders from the Stanford Sleep and Dreams website.
Absolutely! Particularly if you carry the knowledge through your entire lives. And it is not difficult. The six year old son of one of my sleep specialist colleagues once diagnosed a specific sleep disorder in a man sitting nearby on a bus. Everyone should certainly know that sleep disorders exist and when to seek help. Almost all sleep disorders can be effectively treated or cure, and there is absolutely no reason to suffer needlessly. Unfortunately, the vast majority of sleep disorders victims do suffer needlessly because most people do not know about sleep disorders.
In the annual surveys I carry out in my course, almost all students know someone, usually a parent or close relative, who has totally unambiguous sleep disorder symptoms.
Though some are rare, most sleep disorders appear to be highly prevalent. The national prevalence has been established scientifically for one specific disorder, obstructive sleep apnea. This disorder afflicts 24 percent of adult males and 9 percent of adult females which extrapolates to 30 million Americans. Of these, about 20 million are in the early stages, and about 10 million have progressed to a level of severity that requires treatment. Of greater relevance to students is that we found the problem in about 8 percent of a fairly large sample. The Restless Legs Syndrome has been estimated to afflict at least 12 million Americans. A recent Gallup Poll has established a national prevalence of 14 percent for chronic insomnia. The same poll reported that half of all adults have had difficulty sleeping at one time or another.
In 1991, the answer to this question was a resounding no. In 1997, the answer is only slightly better. Although serious sleep disorders are relatively uncommon in the undergraduate population, they are unfortunately far from absent. In the vast majority of cases, undergraduates who have specific sleep disorders do not receive proper diagnosis and treatment.
The single most important thing to remember from this document is that drowsiness means you are seconds away from sleep. Seconds away from sleep may mean seconds away from death. If you are behind the wheel, just a few seconds of sleep can lead to a catastrophic disaster. Many freshmen may not do very much driving, but if you are a passenger, pay attention to the person who is driving. Recently, my limousine driver fell asleep at the wheel. If I had not been paying attention, I would not be here today. All this can be avoided with one simple rule, immediately stop any potentially dangerous activity when you feel drowsy. Encourage others to do likewise.
Drowsiness is red alert! Learn to be sensitive to your level of drowsiness. Being sensitive to your sleep tendency and responding appropriately may save your life.
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