2. It Can Help You Stay Alert and Productive. Caffeine is known for its stimulant effects, which can help you stay alert and productive. However, not all caffeine is created equal. Some sources of caffeine, like coffee, contain more caffeine than others, like tea. Decaf contains less caffeine than regular coffee does, so it may be a good option if you need to stay alert but don't want the stimulant effects of regular coffee.