Passing out after a long night out has been less of a problem thanks to the alcohol-infused energy drinks that have become available over the past few years. But on Friday, the Food and Drug Administration asked manufacturers to prove the safety of the reported drink of choice for a quarter of college students. Those who mix caffeine and alcohol are at a higher risk of injury than those who drink uncaffeinated alcohol, according to a Wake Forest University study. Last year, several state attorneys general successfully sued Anheuser-Busch and MillerCoors to remove caffeine from two drinks. Now, the FDA is asking nearly 30 similar manufacturers to offer scientific proof that their products are safe within the next 30 days. The agency will review the manufacturers’ findings and determine whether the drinks can remain on the market.