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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. 2. 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. 3. 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. | 
