I am always looking for alternative ways to get caffeine and energy without drinking coffee. I've found that the Rockstar Sugar Free Energy Drink is at the top of the list when it comes to energy drinks. The energy lasted me about four hours, and I did not feel groggy afterwards. It also is sugar free so you save yourself a lot of calories! I was not a huge fan of the taste, though. It had that pungent energy drink flavor. I recommend this if you like energy drinks and want to cut back on calories.