ANTH-110 Lecture Notes - Lecture 9: Sleep Debt, Insomnia, Old Age
25 Mar 2016
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Document Summary
He stages of nrem sleep and rem sleep cycle over and over again during a night"s sleep. Stages i, ii, iii, and iv are followed by rem sleep. A complete sleep cycle, from the beginning of stage i to the end of rem sleep, usually takes about one and a half hours. Awakening after a full night"s sleep is usually from rem sleep. Stage i is a stage of light sleep and is considered a transition between wakefulness and sleep. During this stage, the muscles begin to relax. It occurs upon falling asleep and during brief arousal periods within sleep, and usually accounts for 5% to 10% of total sleep time. An individual can be easily awakened during this stage. Stage ii occurs throughout the sleep period and represents 40% to 50% of the total sleep time. During stage ii, brain waves slow down with occasional bursts of rapid waves.
