Does sleepiness make one more likely to engage in stereotyping? Are people more likely to be prejudiced because of a poor night of sleep? Borrowing from ego depletion theory and research on self-control and prejudice, the present work investigates these questions. We suggest that sleep is a diminishable resource that fuels self-control and is, therefore, necessary for inhibiting prejudice. A series of 3 studies show that sleep did influence prejudice. Furthermore, we found that the relationship between sleep and prejudice was marginally moderated by negative implicit associations, such that this relationship primarily held true for individuals who have high negative implicit associations. These results highlight the critical role that sleep plays in suppressing prejudice.