Clinical & Experimental Research , was based on interviews with about 1,100 college seniors . The amount of caffeine in most energy drinks is comparable to that in 1 to 2 cups of coffee . It 's unclear whether energy - drink consumption is directly related to alcohol problems . Energy drinks generated about $ 1 billion in global sales in 2008 .
The amount of caffeine in most energy drinks is comparable to that in 1 to 2 cups of coffee . It 's unclear whether energy - drink consumption is directly related to alcohol problems . Energy drinks generated about $ 1 billion in global sales in 2008 .