If you don’t get much sleep tonight, don’t expect caffeine to help you much tomorrow. In a new study published in the Journal of Experimental Psychology, researchers at Michigan State University tested the effects of caffeine on 275 participants after a night of sleep deprivation. While caffeine did help them complete a simple attention task, they still struggled completing tasks that had to be done in a specific order, without skipping or repeating steps. The researchers warn that caffeine won’t help you avoid sleep-related mistakes at work or while driving. So while a cup of coffee might help after a long night, it doesn’t replace a good night’s sleep.