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what are sleep stages or sleep cycles
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so it's easy to think that there's not
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much going on when you're sleeping
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and until the 20th century it was often
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thought that sleep was just some form of
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unconsciousness
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but the truth is there is an awful lot
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going on while we sleep
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in fact normal human sleep is
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characterized by regular repeating
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patterns of different kinds of sleep and
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brain activity
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we call those different kinds of sleep
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sleep stages
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basically sleep stages are just
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different patterns of brain waves
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measured by an eeg while you sleep
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in the next series of videos i'm going
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to take you through the different stages
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of sleep one by one and give you a
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description of each in a little bit of
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depth