Question: how much caffeine is needed to stay awake?
Answer: Most people need about 100 milligrams (mg) to 200 mg of caffeine, depending on their body weight, Rosekind says. (Coffee has about 100 mg of caffeine in a 5-ounce cup, though the content varies based on the strength of the brew.) Over-the-counter caffeine pills also are available in 100 mg or 200 mg doses.