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Četvrtak, 15. oktobar 2009. - Objavljeno 16:07 GMT

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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:

Jerry Seigel: '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% 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.

Jon Stewart, BBC News

to function well
normalno funkcionisati, opstajati u normalni uslovima

a broad range of
veliki dijapazon, raznovrsni

vary widely
veoma su međusobno različiti, razlikuju se između sebe

migrating birds
ptice selice, ptice koje tokom godine menjaju prebivalište zavisno od vremenskih uslova

to conserve
sačuvati, zaštititi od propadanja

are needlessly active
nepotrebno aktivni, aktivni bez previše potrebe, puno se kreću bez jasne svrhe

vital
esencijalni, najvažniji, vitalni, bez kojih se ne može

limited resources
ograničeni resursi, slabo dostupna hrana

to get injured
povrediti se, slučajno se ozlediti

detected by predators
biti primećen od strane predatora