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Pythons, bats and giant armadillos are among the longest sleepers at over 18 hours a day. Human babies need 16 hours, and most of us probably feel we need around eight hours sleep to function well.
Professor Jerry Seigel, from the University of California, Los Angeles, conducted a study of the sleep times of a broad range of animals, and found that they vary widely. Some, like migrating birds, can survive long periods without sleeping at all. He believes that shows sleep evolved to conserve energy:
"It's animals that are needlessly active that will not survive, but animals that are most efficient and use their waking time to do vital functions, and are otherwise asleep that will survive."
Sleep helps make best use of limited resources. In humans, when we're awake, our brain accounts for 20 percent of the energy we use when just sitting around. Sleeping also makes us less likely to get injured and less likely to be detected by predators.
Vocabulary 词汇
pythons 蟒蛇类动物
giant armadillos 巨犰狳
function well 正常运作
conducted a study 展开了一项研究
migrating birds 迁徙的鸟类
evolved 演变
conserve energy 保存能量
needlessly 不需要地
survive 生存
vital functions 主要的功能
limited resources 有限的资源
accounts for 占... 的比例
sitting around 闲坐着
get injured 受伤
detected 发现/发觉
predators 捕食其他动物的动物