Before the discovery of REM (Rapid Eye Movement during dreaming) it was believed that there was just one kind of sleep state. In 1953 at the University of Chicago, Nathaniel Kleitman and his student Eugene Aserinsky found otherwise. (Aserinsky & Kleitman, 1953) Dr. Kleitman had been studying sleep difficulties in infants and wanted to explore the slow rolling eye movements that babies have at sleep onset. He had his student Aserinsky watch these movements of sleepy infants. What surprised Aserinsky and changed the notion of sleep forever, was the occasional occurrence of very rapid movements of the eyes at various times during the sleep cycle. Though the eyes remained closed, they moved just as if the child was awake and outside playing games. Aserinsky and Kleitman then monitored adults and found the same thing, and that these eye movements lasted anywhere from three to fifty-five minutes (Van De Castle, 1994). Since the movements appeared as if the sleepers were scanning, they decided to awaken them and ask what they were looking at. They were, more often than not, dreaming. When they woke sleepers up when there was no eye movement, they rarely reported dreams. These discoveries were reported in _Science_ on September 4th, 1953 and again in an expanded article in 1955. It was the beginning of what is now 40 years of dream research in the sciences.

While Aserinsky finished his medical program and left the labs, William C. Dement (1976) filled his place and soon was able to characterize sleep in stages. Part of understanding that the REM state is different is that it is a physiologically different state than waking or other kinds of sleep. During REM sleep, there are irregular patterns in breathing, heart rate and blood pressure. Our muscles are tense, though they can twitch and jerk. It is often said that all motor commands from the brain to the muscles are cut off during REM, but this may be a little misleading. As Alan Worsley has stated about the lucid dream state, though somewhat paralyzed, there is a bit of an ability to control the twitching and spasms.

o Stages of Sleep

Although sleep stages are different in every individual an vary from night to night and differ widely from childhood to late adulthood, some generalizations have been observed. After a few minutes of drifting we slide into deeper and deeper levels of what is called NREM or Non-REM sleep. The brain’s waves get wider and slower. After an hour or two the first REM period begins and lasts a few minutes. Then we sink back into deeper and deeper sleep. This cycle occurs about every 90 minutes. Towards the end of the night or sleep period, the REM periods get longer and we don’t sink into quite as deep of sleep.

 Three kinds of measurement used to determine the stage and level of sleep are:

1. EEG: The electroencephalogram to determine electrical activity on the surface of the brain.

2. EOG: The electrooculogram. To measure eye movements.

3. EMG: The electromyogram. To measure muscle tone.

Other measurements include the brain chemistry, EKG or heart rate, respiration and PHG or genital arousal . Newer recording equipment such as the MRI and other digital imaging equipment are slowly being brought into research.

NREM Sleep Stage 1.

• EEG: Beta waves are replaced by Alpha waves characteristic of a meditating mind. (When we are awake, the waves are tight and fast)

• Reactions to outside stimulus diminish. We stop noticing a lot of the noise and lights.

• People awakened from this sleep stage often report just barely being asleep, or just about to fall asleep.

• Short dreams, or dreamlets may be reported. Body jerks and wandering thoughts can occur.

• This sleep stage usually lasts 3- 12 minutes.

NREM Sleep Stage 2.

• EEG: Sleep spindles. That is, twice as slow Theta waves. Occasional spikes called K-complexes and the beginning of large slow delta waves.

. • Not to hard to wake people here, but they usually report being really asleep.

• Lasts 10-20 minutes.

• EMG: Muscles have tone or tension.

NREM Sleep Stage 3.

• EEG: Delta Waves. A little less than half the waves are large, slow delta waves. Spikes and K-complexes occur, but not as much.

• EMG: Muscles have tone.

• Lasts about 10 minutes

NREM Sleep Stage 4

•EEG: Delta Sleep. More than half the waves are large, slow delta wave.

• Sleepers hard to awaken. Children my take several minutes to awaken.

• Combined with stage 3, Lasts 40-90 minutes.

• Sleepwalking, sleeptalking, night-terrors, bedwetting in children.

REM Sleep Stage:

• EOG: Rapid Eye Movements back and forth. Sometimes measured by strain gauges as well.

• EEG much like waking and stage 1

• EKG: Irregular heatbeat compared to NREM

• EMG: muscles loose and relaxed.

• Respiration is less regular than NREM

Waking Consciousness. Compared to REM their are many similarities

About an hour or two into sleep, people move back up through states three, two and one, and often enter the first REM stage of the night. REM sleep is sometimes called "paradoxical sleep" because it has characteristics of both light and deep sleep. The first REM period of the night usually lasts only a few minutes. Then people sink into the deeper stages of sleep again. More REM periods occur and become longer and longer. Near the end of a sleep period, they can last for an hour or more. The NREM or non-REM sleep time are shortened as the night goes on.

By the end of the night, we usually have stopped having state 4 sleep. Near the end of the night (or sleep period) we rotate between stage two at bottom and up to REM.

It is easy to get dream reports from people awakened from REM, but people can dream in any stage. Sawtooth waves occur in the EEG and eyes move rapidly back and forth. Messages from brain are cut off at the brain stem and never reach the body. The body’s heating system is regulated more like a reptile. It assumes the temperature of the surrounding room.

Part of understanding that the REM state is different is that it is a *physiologically* different state than waking or other kinds of sleep. During REM sleep, there are irregular patterns in breathing, heart rate and blood pressure. Our muscles are tense, though they can twitch and jerk. It is often said that all motor commands from the brain to the muscles are cut off during REM, but this may be a little misleading. As Alan Worsley has stated about the lucid dream state, though somewhat paralyzed, there is a bit of an ability to control the twitching and spasms. Still, most of the messages from the brain to the body to act are stopped in the brain itself.

Men and women have about the same sleep stage patterns, but age will make a large difference. A newly born child spend half its sleep time in REM. Premature infants may spend as much as 80% of their time in REM. Older adults will spend less time in REM sleep than other groups.

Nocturnal erections ( tumescence) is often found in REM, though it can begin before the REM period and last after REM has stopped. This seems to begin by the age of three and continue throughout life. There is sometimes a decrease (slight) during times of sexual abstinence, while an active sex life will increase the occasions of sleep erections. Nocturnal emissions have not been associated with REM sleep, but this may be due to the feelings of inhibition that occur in sleep laboratories. There are no age comparison studies for women, but research has found that women in general have a higher VPA (vaginal pulse amplitude) during REM than Non-REM. These VPA scores were seen to be similar to when the same women were show erotic films and material, suggesting that there is an increase in the female genital arousal system during REM.

Two more dream related syndromes need to be mentioned here, hyponagogic and hypnapopmic dreams. Occasionally during sleep there can be an intense imaginary experience. These events are often characterized as being full of light or very vivid and colorful, often quite strange and bizarre and sometimes visionary. Sometimes there are familiar objects, but just as often the scenery is geometric and full of designs. There is often a report of floating, falling, flying or spinning. When this experience is right as we are falling asleep it is called hypnagogic, and when it is right before we wake up it is called hypnapompic.

 The most controversial issue with Rapid Eye Movement sleep is the relationship between REM and dreaming. When Aserinsky and Kleitman first discovered REM, it was hoped that the key to dreaming had been discovered. But this connection between REM and dreaming has led to many controversies and misunderstandings both within science and between science and other fields. For example, one research group found that REM started right after a series of random firings in the brain stem. They concluded from this that dreams themselves were random. You can see how equating REM with dreaming led to this mistake, which is only one of many in the last 40 years.

 At best, we can say safely say that dreams are easier to recall when we are awakened from the REM period of sleep than any other stage. In this sense they are intimately connected. But this connection has really not been drawn any closer than since the first discover by Aserinsky and Kleitman in the 1950's. The opening in the doorway to the mind-body problem has remained mysteriously locked. One of the most respected dream researchers in current years, Harry Hunt, has noted that this may be due to the multiplicity of dream. That is, that dreams and dreaming serve so many different functions that seeking a simple parallel can never satisfy our understanding of the nature of dreaming.

If you are interested in the science of dreaming, the Association for the Study of Dreams publishes a peer reviewed journal  Dreaming  and brings together scientists and researchers from around the world for an annual conference.