Caffeine can give us a boost, but too much can mess with our sleep and make us feel jittery. So how do we know what’s the right amount? Generally, government and health groups recommend that healthy adults consume no more than 400 milligrams of caffeine a day. That comes out to about four, 8-ounce cups of coffee, says Jennifer Temple , a professor of exercise and nutrition sciences at University at Buffalo School of Public Health and Health Professions.

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Persons: Jennifer Temple Organizations: University, Buffalo School of Public Health, Health