(UNICAMP - 2005 - 2a fase - Questão 14)
Who Sleeps?
Reptiles, birds and mammals all sleep. That is, they become unconscious of their surroundings for periods of time. Some fish and amphibians reduce their awareness but do not ever become unconscious like the higher vertebrates do. Insects do not appear to sleep, although they may become inactive in daylight or darkness. By studying brainwaves, it is known that reptiles do no dream. Birds dream a little. Mammals all dream during s leep. Different animals sleep in different ways. Some animals, like humans, prefer to sleep in one long session. Other animals (dogs, for example) like to sleep in many short bursts. Some sleep at night, while others sleep during the day.
Really?
Cows can sleep while standing up, but they only dream if they lie down.
Whales and dolphins are “conscious breathers” and because they need to keep conscious while they sleep in order to breathe, only one half of their brain sleeps at a time.
Adaptado de http://health.howstuffworks.com/sleep.htm
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