Sleep Medicine: A Major Clinical Discipline

This article was originally published in the JUNE 2014 Edition of Sleep & Wellness Magazine; an American Sleep and Breathing Academy publication. It is being republished for the benefit of the author’s institution, for non-commercial and educational use without limitation.

Sleep and Wakefulness are complementary phases in the daily cycle of human existence. Although I understand relatively little about the evolution of life in general and human life in particular, the complexity of the human brain, and the development of consciousness and communication, I have assumed that life evolved in equatorial zones where the light of day and dark of night succeeded one another in a highly regular manner with little, if any seasonal change. I also assume that as humans evolved, they were aware that night did not always entail total darkness. (There were the moon and the stars, after all.) Nonetheless, until man learned to control fire and thus provide some light in the night, as an animal primarily dependent upon vision, humans had to perform almost all their activities in the daytime, of course they also had a biological need to obtain adequate sleep on a regular basis.

By William C. Dement, M.D. , PH.D, DSC. HON

babySleepingI vividly recall visiting the newborn nursery for the first time at the University of Chicago and seeing typical REM in many newborn infants. Nobody believed me. I also noted an even higher percentage of REM sleep in a few premature infants. Today we know that REM sleep is present in newborn babies, at a very high level: 50% of their average daily 16-hour sleep time is REM sleep.

It must be emphasized that even today, we do not know why REM sleep exists and what purpose it serves. There is vast literature of speculations on these purposes of REM sleep, but nothing is established as certain fact. It is obvious that non-REM sleep fosters alertness during the daytime and conserves calories, but that is not necessarily its primary purpose.


It is now a well-established fact that sleep consists of two entirely different states: REM sleep (a period of rapid eye movement) and non-REM sleep. This fact was discovered in the 1950’s, when it was first possible to create continuous brainwave recordings. I was one of the key researchers in those early days of sleep science, and I have continued the study of sleep throughout my professional career. When I carried out the first all night, continuous brainwave and eye movement recordings, I discovered the regular alternation between the two types of sleep. In addition, I found that REM sleep occupied around 25% of the night on average, while the remainder was non-REM sleep. These early findings about REM during sleep were reported and published in the scientific literature by Aserinsky, Kleitman and me, and today they are broadly accepted.


During my early studies, I observed that brain activity was elevated during periods of REM sleep, while the body was essentially paralyzed. I suspected that REM sleep might be when dreaming occurred. Accordingly, I scheduled a study with a series of arousals during the two separate states. After several hundred of such awakenings, it was absolutely clear that vivid, complex dream adventure stories were reported after REM awakenings, while highly simplified—or no reports at all—were reported after non-REM arousal’s.

It is now apparent human beings live in two worlds: the “real world” and the “dream world.” One major difference between the two is the continuity of the real world from day to day and the discontinuity of the dream world, both from one period of REM sleep to another and from night to night. Dreams may include continuing themes, but those themes are rarely obvious.

Another insight from my study of sleep and dreams was that, rather than being a virtually instantaneous scene or two, dreams actually involved long, continuous adventures. However, the recall of a dream was rarely as accurate and detailed as recall of a wakeful activity. Further, studies showed that individuals awakened from REM sleep varied greatly in their ability to recall their dreams—from people who never remembered a dream to people who had complex recall from every REM period arousal. An individual’s ability to recall dreams did not appear to relate significantly to other qualities of the individual, such as waking memory, IQ, or other personality variables.

Since REM sleep was discovered in infants, there has been a controversy regarding whether babies dream during their eight hours of REM sleep. Rudiments of dream recall are certainly present in 1- and 2-year-olds, and by the time children are three or four years old, they can recall dreams nearly as vividly as adults.

People have believed that dreams were caused by stimuli from the environment, including some unique ideas like eating cheese sandwiches. Scientific study has revealed a few facts about dreaming:

  • We dream in color.
  • The course of time in the dream world is approximately the same as in waking world.
  • Dreams are not continuous through the night, and are not very much influenced in terms of events on the previous day.


As sleep was considered essentially one step up from death for ages, studies that discovered high levels of brain activity during sleep led to a tremendous upgrade in scientific interest in sleep. Since 1952, when there was one laboratory carrying out all-night, sleep electro-physiology recording, there has been enormous growth in the discipline of sleep study.

In the early days, I was not allowed to study the sleep of adult females. My professor was somewhat fearful that a scandal could result from a female staying all night in a bedroom with a male. It has been rumored for years that I got married to have a “safe” female subject. Today there are more than 2000 sleep laboratories. The vast majority of such laboratories are clinical facilities to examine and treat individuals who have problems sleeping.


The increased number of sleep laboratories and sleep studies has been instrumental in characterizing a number of sleep disorders. Today, there are over 80 recognized sleep disorders. The most common disorders are nightmares (which range from uncomfortable to terrifying), obstructive sleep apnea (OSA), Restless Leg Syndrome (RLS), and a collection of insomnia’s.

OSA is the most common destructive sleep disorder. An individual who experiences 5 apnea events per hour during sleep is diagnosed as having OSA. In the U.S., it affects about 25% of adult males and 9% of adult females. In other words, over 30% of Americans are afflicted OSA. If OSA remains unrecognized and untreated it can eventually, mainly though the development of hypertension and heart problems, lead to death. Individuals with untreated OSA must wake up to breathe properly, so another great problem is that they tend to be tired and drowsy during the daytime. The most obvious risk in this condition is the drowsy driver.

ManFellAsleepBooksTwo other distinct disorders, which my research team characterized, involve REM sleep. The first is narcolepsy. The odd collection of symptoms that characterize narcolepsy were first reported in 1880 and continued to be a mystery until recent years. The second illness is REM Behavior Disorder. It too had to await the discovery and understanding of REM sleep before it was understood.

Narcolepsy involves a collection of signs and symptoms, which include persistent daytime sleepiness, attacks of sleep paralysis, and hypnagogic hallucinations— shapes, colors, or images, sometimes accompanied by sounds, experienced during the period between wakefulness and sleep.

As a result of strong emotion, patients with narcolepsy have attacks of cataplexy, or body weakness or paralysis that usually accompanies dreaming, when they are awake. Narcolepsy is understood better now that we know that patients are experiencing misplaced, physical characteristics of REM sleep instead of strange, random symptoms (even though they are not asleep).

REM Behavior Disorder is the opposite of narcolepsy. Patients with this problem are not protected by the muscle paralysis that generally inhibits violent movement during dreaming. Patients can be injured or hurt others by acting out their dreams.


Today we know that it is impossible for human beings to go without sleep for more than a day or two solely because they want to. People may be kept awake for a long period of time only if they are perpetually stimulated and carefully watched by others, as their tendency to fall asleep strongly increases with cumulative time awake. Tired people do not function well until after they are able to get some rest.

Although I have said that sleeping at night and engaging in wake activities during the day was an excellent adjustment to the earth’s rotation, with modern technology, our lives run 24 hours a day, 7 days a week. Our fire and police departments, factories, and hospitals operate around the clock. Nonetheless, most human beings sleep and dream at night.

In my onion, the biggest problem with regard to sleep is the failure to deal with the topic adequately in the mainstream educational system. Most people today have not learned about sleep or the impairments caused by sleep deprivation. If I ask a large group of Stanford University freshmen if they were taught the details of sleep knowledge in high school, the vast majority say no. As a result, they are vulnerable to the impairment of sleep disorders and sleep deprivation. Healthy sleep is associated with optimal performance. Healthy sleep involves a sufficient amount and continuity of sleep to avoid sleep indebtedness, or the cumulative effects of too little sleep. Healthy sleep is also reasonably synchronized with the circadian predisposition to sleep and wake; in other words, people with healthy sleep patterns are able to wake and sleep at the appropriate times.

I’m currently studying the effect of extra sleep on Stanford varsity athletes. Preliminary results suggest there is a statistically significant improvement in an athlete’s personal best and their overall performance when they obtain extra sleep. There are almost no individuals who cannot obtain extra sleep by going to bed earlier than usual or sleeping later than usual. Probably most human beings go through life slowly accumulating sleep debt; at some point, they must obtain extra sleep to continue their regular activities. This cycle is repeated over and over.

Our 24-hour “on” lives makes us vulnerable to the dangers of too little sleep. If I could tell people one thing to protect themselves and avoid problems associated with too little sleep, it is this: the absolute most important thing to be fully aware of is the moment of drowsiness, the moment when a conscious effort of will is required to keep your eyes open. Drowsiness is a red alert that you need sleep. If you are drowsy, stop what you are doing and rest!


DrDementDr. William Charles Dement is commonly known as the father of sleep medicine. He is completing his 56th year of sleep research, which has been instrumental in defining and developing the clinical discipline of sleep medicine. He has written textbooks, is the author or co-author of over 500 scientific publications, and is public policy leader in applying sleep knowledge to families, workplaces, and safer transportation throughout America.Dement also teaches undergraduates, medical students and primary care physicians. He is affiliated with the Lowell W. and Josephine Q. Berry Professor of Psychiatry and Behavioral Sciences at the Stanford University School of Medicine, and he is the Director Emeritus of the Stanford Sleep Disorders Clinic and Research Center. Dement was appointed in 1990 as Chairman of the National Commission on Sleep Disorders as federally mandated by the U.S. Congress. He was co-founder of the Sleep Research Society in 1961 and founded and led the American Academy of Sleep Medicine for its first twelve years (1975-1987). Dement’s “Sleep and Dreams” course at Stanford University is oneof the most popular and largest classes offered.

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