职称英语理工类教材阅读理解的文章及译文(5)

　　Late-Night Drinking 　　Coffee lovers beware. Having a quick pick-me-up cup of coffee1 late in the day will play havoc with2 your sleep. As well as being a stimulant, caffeine interrupts the flow of melatonin, the brain hormone that sends people into a sleep. 　　In the second phase of the experiment, the researchers woke the volunteers every three hours and asked them to give a urine sample, Shilo measured concentrations of a breakdown product of melatonin. The results suggest that melatonin concentrations in caffeine drinkers were half those in decaf drinkers. In a paper accepted for publication in Sleep Medicine, the researchers suggest6 that caffeine blocks production of the enzyme that drives melatonin production. 　　1. The author mentions pick-me-up to indicate that 　　B neurohormone can wake us up. 　　D decaf is a caffeinated coffee. 　　A Caffeine blocks production of the enzyme that stops melatonin production. 　　C Caffeine halves the bodys levels of sleep hormone. 　　3. What does paragraph 3 mainly discuss? 　　B Different findings of Lotan Shilo and a team about caffeine. 　　D The proof that the subjects took half an hour to fall asleep. 　　A There are more enzymes in decaf drinkers urine sample. 　　C Decaf drinkers produce less melatonin. 　　5. The author of this passage probably agrees that 　　B we should not drink coffee after supper. 　　D if we feel sleepy at night, we should go to bed immediately.