The Psychology of Sleep and Dreams

Psychology is the scientific study of behavior and mental processes.

Behaviors are actions that can be directly observed.

Mental processes are activities that cannot be observed directly, such as consciousness, thinking, reasoning, perception, learning, memory, emotions, motivation, and even biological activities.

As a comprehensive science of behavior, psychology is concerned with the behavior and mental processes that occur while we are awake, asleep, and during dreams.

Why Study the Psychology of Sleep and Dreams?

We all do it and spend a lot of time doing it
We spend more time sleeping than anything else’ In fact, we spend about one-third of our lives asleep.

So, if you live to be ninety years-old, you will have spent thirty years sleeping, and six of those years dreaming!

Surprisingly, we are not really sure why we sleep - or why we sleep so much.

  • how much sleep do we need?
  • What happens when we don’t get enough sleep?
  • Why do we fall asleep or wake up?
  • What purpose does sleep serve?
  • Why do we sometimes have trouble falling asleep, staying asleep, or waking up?
  • What factors influence the quality of sleep?
Everyone dreams

With very rare exceptions, all of us dream.

We average between four to six dreams each night, or about 2,190 dreams a year.

If you live to be ninety, you have had over 190,000 dreams!

Yet, while we do a lot of dreaming, we typically remember very few, and some people report never remembering their dreams.

  • why do we have dreams?
  • What makes us dream?
  • Do they serve a purpose?
  • What determines the content of dreams?
  • Why do we sometimes have frightening dreams or nightmares?

Dreams fascinate most of us and can be fun to explore, but do they have meanings?

We’ll explore these questions.

Sleep disorders are common and seriously affect quality of life

Sleep disorders affect an estimated 40 million people in the United States, and about 20 million more experience occasional sleep problems.

Sleep disorders are serious condition that can have profound adverse effects on daily cognitive, emotional, and physical functioning.

Some sleep disorders increase the risk for serious health problems, including diabetes, obesity, heart disease, stroke, and even death.

So, what are sleep disorders and how can we recognize them? What causes them? How can they be treated?

Considering all the compelling reasons listed above, it is surprising how little most of us know about sleep -
and most of us take it for granted, or worse, think it’s a waste of time! Biologist Paul Martin (2002) comments:

"The scientists who do know something about sleep often bemoan society’s ignorance of it. They point to the vast gap between current scientific understanding of sleep, patchy though it is, and the practical benefits it could bring if that knowledge were absorbed and acted upon by society. Our collective indifference towards sleep has enormous and largely avoidable
costs" (Martin, 2002, p4).

The Mystery of Sleep: A Brief History

The scientific study of sleeping and dreaming really only began relatively recently.

Yet, an interest in the mystery of sleep:

  • What is it?
  • What is it for?
  • Where do we go when we’re sleeping?
  • What are dreams?,

were central concerns of most ancient cultures.

As evidenced by the many beliefs, myths, and theories about sleep and dreams found throughout history, our ancestors had keen interest and need to understand this strange state we enter into each night.

Ancient cultures thought dreams were messages from the gods, visitations from demons or dead ancestors.

Dreams were thought to predict the future, provide warnings, and provide guidance for the dreamer.

For the ancient Egyptians, Greeks and Romans sleep and dreams were the work of gods: Tutu (Egyptian), Hypnos (Greek), Somnus (Roman) were the gods of sleep and Morpheus (Greek and Roman), and Serapis (Egyptian) were the gods of dreams.

Early Science

Rather than visitations from the gods, some of the ancient Greeks proposed a more scientific explanation of sleep and dreams.

Greek philosophers held that sleep was caused by such things as blood rushing to the brain (Alcmaeon) or digestive vaporsrbato, Aristotle), and that dreams were nothing more than “thinking while asleep” (Rock, 2004).

Over the following centuries philosophers speculated that sleep was caused by everything from an accumulation of blood in the brain to a build up of “hypnotoxins”.

Sleep was a passive state of unconsciousness, a kind of intermediate state between wakefulness and death, in which the brain is inactive.

The Psychology of Sleep and Dreams


For centuries sleep and dreams were left to the speculation of poets and philosophers and not considered a worthy subject for scientists.

In 1900, Sigmund Freud reawakened interest in the study of sleep and dreams with the publication of his The Interpretation of Dreams.

Freud held that dreams were the “royal road” to the unconscious mind and used dreams to understand and treat patients’ mental health disorders.

Freud’s ideas would dominate thinking about sleep and dreams for the next fifty years.

Historical Perspectives on Sleep and Dreams

Sleep is an intermediate step between being awake and death.

Sleep is a “short death” and death is a “long sleep”.

During sleep and dreaming the soul leaves the body.

Dreams are a direct message from God or the gods.

Dreams were visitations from demons or the dead.

Dreams provide predictions and warnings about the future.

Dreams are caused by eating the wrong things, eating at the wrong time, etc.

Sleep is caused by blood rushing to and putting pressure on the brain

Sleep is caused by a lack of blood in the brain.

Sleep is caused by vapors from digesting food rising to the brain.

Sleep occurs when there is insufficient stimulation to keep the brain awake.

Sleep is caused by a buildup of “hypnotoxins” that temporarily poison the brain.

Sleep is a passive state caused by the general slowing down or shutting off of brain function.

Sleep occurs when brain cells (neurons) become paralyzed and unable to communicate.

The Psychology of Sleep and Dreams

The Discovery of Brain Waves

By the late 19th century sleep was still viewed by most as a passive process; a period of lowered brain activity when the brain shuts off.

This would eventually be shown to be incorrect, thanks, in large part to technological advances the late l800s that would lead to the birth of a true science of sleep.

In 1875, English scientist Richard Caton, using a crude volt meter discovered the spontaneous electrical activity in the brains of animals.

Then, in l920s, German scientist Hans Berger invented the electro encephalograph (EEG), a device that measures and records the brains electrical activity, and it was this invention ushered in the development of the scientific study of sleep.

Berger became the first to record human EEGs and the first to identify and describe different patterns of the brain’s electrical activity - called “brain waves” and correlate them to specific states of consciousness.

He was also the first to observe changes in the brain’s electrical activity during sleep.

The invention of the EEC was a major breakthrough in neurology and psychiatry and an important tool in
diagnosing neurological disorders like seizures, head injuries, and brain tumors.

It would also become invaluable in the scientific study of sleep and dreams.

Nathaniel Kleitman: The Birth of Sleep Science

In the late l920s physiologist Nathaniel Kleitman at the University of Chicago set up the world’s first laboratory to study sleep.

When he began his research, Kleitman, like most scientists of his time, believed that sleep was a completely passive processes, and that relatively little happened during sleep.

Kleitman’s research showed, instead, that sleep is a dynamic process regulated by a very active brain.

Kleitman’s conducted groundbreaking research on such things as the regulation of sleep and wakefulness, sleep and biological rhythms, the basic characteristics of sleep, and sleep deprivation.

In 1939 Kleitman published his landmark book which spawned a new generation of sleep researchers, which would include some of the most influential names in the history of sleep research.

The Discovery of REM

In 1953, Kleitman and his student Eugene Aserinsky, with the assistance of a young medical student named William Dement, made the first observations of rapid eye movements (REM) during sleep.

Before this discovery, sleep was viewed as a single state.

This discovery immediately showed that sleep consisted of two fundamentally different states.

Although it took some time before the significance of the discovery would be fully recognized, it is the dicovery of REM that really marks the beginning of modern sleep science.

In 1953 Eugene Aserinsky received his PhD. and left the University of Chicago, leaving Dement as director of the sleep lab, and “the only person in the world, so far as I know, who was staying up all night long to observe sleeping human beings” (Dement, l995,p.28).

Dement was the first to conduct continuous all-night EEG recordings of sleeping subjects and show that REM occurred regularly throughout the night and was associated with dreaming.

He also identified the stages of sleep and the ninety minute sleep cycle, discovered REM sleep in animals and newborn babies, and demonstrated  that the patterns of specific rapid movements are related to the visual experiences of the dream.

Dr. Dement:
The First Sleep Research Center and Sleep Disorders Clinic

In 1963 Dr. Dement joined the Psychiatry Department at Stanford University, where he founded the Stanford Sleep Research Center, the first such center in the world and in 1970, founded the world’s first Sleep Disorders Clinic.

Dement introduced all-night sleep lab examinations of patients with sleep related complaints and developed objective assessment of the relationship between night time sleep and day time functioning.

In 1973 he discovered narcolepsy in dogs arid developed the world’s only research colony of animals with narcolepsy, which lead to the identification of the biochemistry and genetics of narcolepsy.

The Development of Sleep Science

Since those early days at the University of Chicago, sleep science has emerged as a major field of research.

In the 60 years since the discovery of REM, sleep scientists have made many important breakthroughs, including the discovery of the basic processes involved in sleep and dreams and many of the neurological and physiological factors involved in sleep.

Since the 1970s the new field of sleep medicine has emerged as an important medical specialty.

Sleep specialists have now identified and developed treatments for more than 80 types of sleep disorders.

Yet, with all the advances made during the past few decades, many researchers believe that we are just now entering a “golden age” of sleep research.

What is Sleep?

Sleep is universal among humans and all complex living organisms (mammals, birds, reptiles, amphibians, fish, mollusks, and insects), and it is necessary for survival.

But what is it? This may seem like a silly question.

After all you’re probably pretty certain that you can easily detect when someone is sleeping and when they’re not (actually, we’ll see it isn’t always so easy to detect).

But, if we are going to study sleep scientifically we have to define what it is.

Sleep is generally characterized as

1)    a brain process, characterized by dramatic, measurable changes in brain activity,

2)    it is a homeostatically regulated process,

3)    it is an active process - the brain can be even more active during sleep as it is during wakefulness,

4)    it is not a single process, but a complex series of stages,

5)    it is episodic process - it occurs in daily alternating cycles with wakefulness,

6)    it is promptly reversible - that is, the sleeper can readily be awakened from sleep – this distinguishes sleep from anesthesia or coma,

7)    it is marked by perceptual disengagement from the external world

8)    it is associated with motor inhibition. decreased movement.

Why Do We Sleep?

After more than 50 years since the beginnings of the scientific study of sleep and dreams it says something about the complexity of sleep that an scientists still don’t know why we sleep.

However, there are multiple theories concerning the function of sleep - and each has some validity.

We will discuss the functions of sleep in greater detail later, but I’ve outlined some of the primary functions of sleep proposed by the various theories, below.

• sleep restores the brain and body to optimal operating condition

• it is necessary to maintain optimal mental and physical health,

• is needed for body repair, restoration, and growth,

• is necessary for the conservation and replenishing energy,

• is necessary for proper immune function,

• promotes brain development,

• promotes learning and memory consolidation.

Perhaps Dr. Dement summed it up best when he said: “As far as I know, the only reason we need to sleep that is really, really solid is because we get sleepy.”

The process of sleep, if given adequate time and the proper environment, provides tremendous power.

It restores, rejuvenates, and energizes the body and brain.

The third of your life that you should spend sleeping has profound effects on the other two thirds of your life, in terms of alertness, energy, mood, body weight, perception, memory, thinking, reaction time, productivity, performance, communication skills, creativity, safety, and good health. - James Maas, 2001

Methods of Studying Sleep and Dreams

Polysomnography (PSG)

Polysomnography (Greek: polus = “many’; Latin (“somnus”= sleep; graphein = “to write”), is the comprehensive recording of brain waves, eye movements, muscle activity, heart rhythm, and breathing during sleep.

Often referred to as a “sleep study”, polysomnography is a standard method for to study/record in detail all the biophysiological changes that occur in the human body when the person is asleep.

A comprehensive PSG sleep study may include the following measurements:

1)    Brain waves: Electroencephalogram (EEG)

2)    Eye movements: Electrooculogram (EOG)

3)    Skeletal muscle activation: Electromyogram (EMG)

4)    Heart rhythm: Electrocardiogram (EKG or ECG)

5)    Respiration rate and effort

6)    Blood oxygen levels: (oximetry)

7)    Leg movements: EMG

8)    Sounds of snoring, gasping, etc.

9)    Video recording of sleep activity

An essential tool used in basic sleep and dreams research, polysomnography is also commonly used to detect and identify sleep disorders like obstructive sleep apnea(OSA), narcolepsy, insomnia, REM behavior disorder, and hypersomnia.

Typically, polysomnography is an overnight sleep study, conducted at a sleep center or hospital.

Back in the days before computers it took nearly a half mile of graph paper to record a single night’s sleep!

Electroencephalogram (EEG)

The characteristic electrical changes in the brain that occur during sleep can be measured and studied using machines called electroencephalographs (EEGs).

In an EEG ,sensitive electrodes are placed at certain standard positions on the surface of the subject’s skull.

Electrodes are wires that are either taped to the scalp individually or fitted to an “electrode cap” that the subject wears during the procedure.

During the procedure, the EEC detects and records the electrical activity produced by the firing of the brains neurons while the subject is sleeping or engaged in a specific task.

EEG studies scientists have led to the discovery of four distinct patterns of electrical activity, called brain waves, that are useful in studying sleep and wakefulness : beta, alpha, theta, and delta waves.

Other types of waves produced during sleep called “spindles” and “K complexes” are also identified by EEG recordings.

Brain waves are identified according to: a) the frequency of the wave : the number of times the wave occurs during a specific period (usually on second), b) the amplitude of the wave: the size of the wave.

EEC brain wave recordings have helped sleep researchers identify and study different types and stages of sleep.

Continuous (overnight) EEC recordings are is considered the most important method used in the study of sleep.

Electrooculagram (EOG)

The electrooculagram or EOC is a device that measures eye activity.

Distinct eye movements are associated with the different stages of sleep.

For example, you are probably familiar with the rapid, back and forth eye movements associated with the stage of sleep called rapid eye movement or REM sleep.

Electromyogram (EMG)
The electromyogram, or ‘EMC’, is used to measure the muscle tension and activity that occurs during sleep.

The EMC is particularly helpful in identifying the different stages of sleep and certain sleep disorders.

The Discovery of Sleep Stages and Cycles

All night polysomnography led to Kleitman and Dement~s discovery that there are two distinct types of sleep, Rapid Eye Movement sleep (REM) and Non Rapid Eye Movement sleep (NREM).

Non Rapid Eye Movement sleep consists of four stages of sleep, ranging from very “light sleep” stages Ni and N2 to the deep, “slow wave” sleep associated with stages N3 and N4.

REM sleep is a separate stage and is generally associated with vivid dreams.

Sleep Cycles

Dement also discovered that the sleep stages are repeated four to six times in a series of 90 minute cycles over a night’s sleep.

Outlined below is a typical night’s sleep in which the sleeper alternates between NREM and REM several times across the night.

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Dr. William Charles Dement

Born 1928, Dr. Dement is a pioneering US sleep researcher and founder of the Sleep Research Center, the world's first sleep laboratory, at Stanford University.

He is a leading authority on sleep, sleep deprivation and the diagnosis and treatment of sleep disorders such as sleep apnea and narcolepsy.

For this pioneering work in a previously uncharted field, he is sometimes referred to as the Father of Sleep Medicine.

In the 1950s as a medical student at the University of Chicago, he was the first to intensively study the connection between rapid eye movement and dreaming.

His fellow student Eugene Aserinsky had mentioned to him that "Dr. Kleitman and I think these eye movements might be related to dreaming".

Aserinsky, along with his and Dement's adviser Nathaniel Kleitman, had previously noticed the connection but hadn't considered it very interesting.

Dement had an interest in psychiatry, which in those days considered dreams to be important, so he was excited by the discovery and was eager to pursue it.

He began his work in sleep deprivation at Mount Sinai Hospital in the late 1950s – the early 1960s.

He was among the first researchers to study sleeping subjects with the electroencephalogram (EEG).

He wrote "I believe that the study of sleep became a true scientific field in 1953, when I finally was able to make all-night, continuous recordings of brain and eye activity during sleep."

Studying these recordings, he discovered and named the five stages of sleep.

In collaboration with Dr. Christian Guilleminault, Dement proposed the measure that is still used for the clinical definition of sleep apnea and the rating of its severity, the Apnea Hypopnea Index (AHI).

Dement, Professor of Psychiatry and Behavioral Sciences at Stanford University School of Medicine, taught the large and popular "Sleep and Dreams" course at Stanford from 1971 until 2003.

Due to popular demand he decided to teach the class again in 2006 and has continued to teach till this very day.

Dement has been spending a great deal of time focusing on spreading information about the danger of driving when drowsy and obstructive sleep apnea.

In 1975 he launched the American Sleep Disorders Association, now known as the American Academy of Sleep Medicine, and served as president for its first twelve years.

In that same year he and Mary Carskadon invented the Multiple Sleep Latency Test used to measure sleepiness, a test of how quickly people fall asleep, sleep onset latency, during several daytime opportunities.

He was also chairman of the National Commission on Sleep Disorders Research, whose final report led directly to the creation of a new agency within the National Institutes of Health, the National Center on Sleep Disorders Research.

Dement is the author of numerous books, including The Promise of Sleep and The Sleepwatchers, and has written the first undergraduate textbook in the field.

At the start of his academic career, he was a jazz musician and played bass.

While at the University of Washington he jammed with Quincy Jones, a time during which he also befriended Ray Charles.

During the late 80s, while at Stanford, he was known to have played, on at least one occasion, with artist-in-residence, Stan Getz.

He lives with his family in northern California.

(Source: Wikipedia)

Tribute to Dr. William C. Dement

Dr. William Dement at Google Talks

Drs. Meir Kryger and William Dement