Before deciding on an energy drink, it is important to understand what it contains and how it can help you stay awake. There are several factors to consider, such as caffeine levels, L-Theanine content, and tyrosine. Caffeine is the most common ingredient, but it is not the only one. There are other factors, including vitamins and other nutrients that can help you stay awake for longer and keep you performing at work, at home and at play.