Multiple Choice, Multiple Answers (Reading) — practice #rmcma-009

Caffeine is the most widely consumed psychoactive substance in the world, found in coffee, tea, cocoa and many soft drinks. It works mainly by blocking adenosine, a chemical that builds up during the day and makes us feel drowsy; with adenosine suppressed, we feel more alert. Moderate intake can sharpen attention and improve performance on tedious tasks, and several large studies link regular coffee drinking with a modestly lower risk of certain illnesses. The substance is not without drawbacks, however. Consumed late in the day it can disrupt sleep, and abrupt withdrawal often brings headaches and irritability because the body adapts to its presence. Sensitivity varies widely between individuals, partly for genetic reasons, so the same cup that energises one person may leave another jittery and unable to rest.