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Now, complete this short article with the right articles.

ARTICLES (a, an, the, or no article)
Gap-fill exercise

DO WE REALLY NEED TO SLEEP? Complete the text using the indefinite article ("a" or "an"), the definite article ("the") or no article ("-"). Sleep is (1) powerful influence on all our lives, and a 60-year-old person has spent almost twenty years asleep. The traditional theory about (2) sleep is that our brain needs to rest for several hours to refresh itself and to 'file' in our memory everything that has happened to us during the day. We can put off sleeping for a limited period, for instance if we go to (3) all-night party, but sooner or later we have to sleep. If we are not allowed to sleep, we suffer hallucinations, and eventually die. However, Dr Ray Meddis has a fascinating new theory. He suggests that we don't really need to sleep at all. We sleep only because our brain is 'programmed' to make us do so. he believes that (4) sleep instinct originates from prehistoric times. Primitive man was 'programmed' to sleep to protect himself from the darkness with its many dangers. Animals seem to have been similarly programmed. (5) number of hours they sleep does not depend on physical activity but on how much time they need to eat. Horses, cows and (6) elephants, for example, which spend many hours eating, sleep only 2 or 3 hours. Cats, on the other hand, who have (7) lot of spare time, sleep for 14 hours (8) day, more than half their lives. According to Dr Meddis, the 'tiredness' we feel at (9) end of (10) day is produced by a chemical mechanism in the brain which makes us sleep. We are 'programmed' to feel 'tired' or 'sleepy' at (11) midnight, even if we have spent the day relaxing on the beach or doing nothing. Dr Meddis believes that the unpleasant symptoms we suffer when we don't sleep enough are not because we have not rested but because we have disobeyed our brain's programming. (12) longer we don't sleep, (13) worse we feel. But Dr Meddis believes that if scientists could locate and 'turn off' the sleep mechanism in our brain that produces tiredness, we could live completely normal and healthy lives without sleeping. So is sleeping (14) waste of time? Well, even Dr Meddis does not deny (15) great psychological value of sleep, and he asks us, "if scientists invented (16) pill which, if you took it, would keep you awake for ever, would you take it?"

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