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The Neurophysiology of Sleep and Dreams Essay

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The Neurophysiology of Sleep and Dreams

The ancient Babylonians thought dreams were messages from supernatural beings, and that the good dreams came from gods and that bad dreams came from demons. (1) Since then people have sought many different explanations for the occurrence and importance of dreams. Before beginning to understand the function or significance of sleep and dreams, it is important to look at when, what, where, and how dreaming and sleeping occur.

Adult humans sleep, or should sleep, for about eight hours a day. People's necessary time spent sleeping changes over time. Newborns spend about twice as long sleeping. (2) Circadian rhythms, [the term originates from the Latin, "circa diem," which means about "about
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The release of different neurotransmitters in different areas seems to determine which type of sleep should be activated. At the onset of sleep serotonin is secreted and seems to trigger NREM. (4) NREM switches to REM sleep with the release of the chemical, acetylcholine, in the pons, which is located in the base of the brain, and later the re-release of noradrenaline and serotonin seems to switch off REM (5) (7) and reactivate NREM sleep again. The action of the neurotransmitters as triggers of NREM and REM sleep is referred to as the reciprocal interaction/activation synthesis. (5) With the excretion of acetylcholine, signals from the pons are sent to the thalamus, which relays them to the cortex, and also sent to shut off the neurons in the spinal cord, which causes the temporary paralysis of the body.

Although the pons is responsible for REM sleep, dreams originate in areas in both the frontal lobe and also at the back of the brain. In twenty-six cases in neurological literature about damage to the pons, although there was a loss of REM sleep in all of them, loss of dreaming was reported in only one of the cases. (5) Also while damage to frontal areas of the cortex makes dreaming impossible, the REM cycle of the individual, whose brain is damaged that way, remains
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