Quote:
Originally posted by Some guy from howstuffworks.com
Reptiles, birds and mammals all sleep. That is, they become unconscious to 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 not dream. Birds dream a little. Mammals all dream during sleep.
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.
Interesting fact:
Cows can sleep while standing up, but they only dream if they lie down!
Whales and dolphins are \"conscious breathers,\" and they need to keep breathing while they sleep, so only one half of the brain sleeps at a time!
I hope I have been more enlightening than O'nus.... :P