This is the 2007 version. Click here for the 2017 chapter 03 table of contents.

Sleep

Sleep is sometimes called the forgotten third of existence. It is an altered state of consciousness we experience—and mostly forget—nearly every night. For the first half of the 20th Century, sleep seemed to be forgotten by psychological researchers as well. A typical psychology textbook of the 1920s through 1940s devoted only a few paragraphs to the subject of sleep. However, information about sleep and dreaming accumulated at a rapid pace during the 1950s and 1960s, an era known as the Golden Age of Sleep Research.

When did the "Golden Age" of sleep research take place?

The Discovery of REM sleep

The Golden Age of Sleep Research began in 1952 with observations of body and eye movements by infants and adults during sleep. The research was carried out by a graduate student, Eugene Aserinsky, in a pioneering sleep laboratory at the University of Chicago. Aserinsky recorded movements of sleepers on film. As he wrote in his 1953 dissertation:

How does the EEG look during REM sleep? What happened when people were awakened during REM sleep?

A new type of eye movement was discovered to occur in the sleep of adults and a child but not in infants. Motion pictures confirmed the presence of these eye movements, which were binocularly synchronous, rapid and jerky. It was suggested that they be termed "rapid" eye movements in contrast to the slow eye movements previously reported. (Aserinsky, 1982, p.1274)

Rapid eye movements (REMs) are very rapid-up to 8 movements back and forth per second-so they look like tremors or vibrations of the eyes, not normal eye movements. They occur in bursts sometimes called REM storms.

Aserinsky soon realized REMs occurred during a distinctive phase of sleep known since the 1930s. During this phase of sleep, a person's brain waves (electroencephalograph or EEG recordings) show an active alert pattern. The pattern is identical to the EEG of a person who is awake and thinking. Aserinsky wondered if this indicated the sleeper was dreaming. Sure enough: people awakened during the REM stage reported dreams 70 to 80 per cent of the time.

How does non-REM sleep contrast with REM sleep?

The phrase REM sleep refers to more than just eye movements. REM sleep is a distinctive stage of sleep identified by many criteria. The eyes do not move constantly; sometimes there are 5 minutes between bursts of REMs while a person remains in REM sleep by other criteria. During REM sleep there is an aroused EEG pattern, muscle relaxation below the neck, fluctuating heart rate and rapid changes in breathing rate. Human males have an erection and women have increased vaginal blood flow during REM sleep. This generally has nothing to do with sexual content of dreams; it is part of the overall REM sleep pattern.

During the other type of sleep, called non-REM sleep, the EEG shows large, regular waves. Breathing and heart rate are slower and more regular than during REM sleep. During non-REM sleep large, slow eye movements occur.


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