Sleep
From Wikipedia, a free encyclopedia written in simple English for easy reading.
A person sleeps when he or she is not awake. Usually, this is during the night. During the day, people are awake. They work, go to school or university, or do other things.
Generally, the reason for sleep is rest. Both humans and the animals who sleep do so about once a day.
When people sleep they usually have dreams.
Not only people sleep, some mammals, birds, and fish do, too.
Scientists think that when animals sleep, their sleep is different from that of humans. Some scientists say that certain animals might not have dreams. Others say physical behaviors might indicate at least basic dreams in some animals, such as when sleeping cats' whiskers twitch or their legs move, as if they were hunting.
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