Information on Sleeping and Dreaming Part 1
A look at the various aspects of sleeping and dreaming including different stages, amounts, research and REM sleep.
Nearly one third of our lives is spent sleeping. Yet only within the last three decades have scientists begun seriously to study, understand, and demystify what goes on when we sleep. The traditional modern view is that sleep represents a stage of renewal, where the body repairs and restores worn-out tissues and cells. There is some truth to this, but we now know that the body is restoring itself when it is awake as well. People used to think that sleep was a period of total inactivity for the body. We now know that a complicated web of chemical interactions occurs while we sleep. The brain, rather than shutting itself off, registers a whole series of electrochemical changes. Scientists working with an electroencephalograph have been able to pinpoint those shifting brain-wave patterns as well as follow the physical changes which occur during our nightly odyssey.
During the night, we do not move seamlessly from consciousness into total withdrawal, but pass through a series of sleep stages. There are four way stations on this nightly journey. The first stage is when we move from the threshold of everyday consciousness into a light slumber. Subtle physiological changes are registered: blood pressure, respiration, pulse rate, and temperature are all on the downswing. Brain waves begin to shift from the smooth rhythms of alpha waves into a more irregular pattern. Stage one lasts maybe 10 minutes. In stage two, the sleeper moves deeper into the netherworld of sleep. At this point, the eyeballs begin to move from side to side, while the amplitude and frequency of the brain waves increase. Stage two usually lasts from 20 to 30 minutes. The sleeper continues his descent into stage three. Total relaxation has set in. Temperature and blood pressure drop even further. By stage four, large, slow, delta waves roll regularly across the EEG (electroencephalograph) screen. This is the stage where the sleeper has abandoned himself to deep sleep. A night's sleep is actually four or five cycles of this movement.
The magic number of eight hours a night is fairly arbitrary, since most doctors recognize that anywhere from six to eight hours is a healthy sleep period, depending on the specific needs and metabolism of the individual. The fact that we do sleep roughly one third of the day, however, is built into our nervous system, programmed there centuries ago. Even without the normal time and light cues, individuals still follow pretty regularly their normal sleeping pattern.
In 1952, Eugene Aserinsky, a graduate student under Dr. Nathaniel Kleitman at the University of Chicago, discovered that a sleeper's eyes darted back and forth behind his eyelids during certain sleep phases. These rapid eye movements, or REMs as they are called, occur with great regularity at roughly 90-minute intervals during the night. REM sleep is called "paradoxical sleep," because it is filled with great internal activity. Breathing becomes irregular, heartbeat rises, and the brain-wave patterns resemble those of the waking state. Most importantly, this is the period where we do most of our dreaming.
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