Recent research proposes that human beings have a limited capacity for self-regulation. Self-regulatory efforts may fail because this capacity is depleted, and such depletion is exacerbated by stress. The present study tested whether academic examination stress would impair regulatory behavior by consuming self-control strength. An exam-stress group was assessed at baseline and then during the commencement of exams; a control group was assessed at two unstressful times. Perceived stress, emotional distress, and regulatory behavior were assessed by questionnaire. During the exam period, the exam-stress group showed impaired performance on a lab task (Stroop) following thought suppression, a form of self-regulatory activity. They also reported significant increases in perceived stress and emotional distress; they also reported an increase in smoking and caffeine consumption; a decrease in healthy eating, emotional control, frequency and duration of physical activity, maintenance of household chores and self-care habits, attendance to commitments, and monitoring of spending; and a deterioration in sleep patterns and study habits. The control group showed no systematic changes in the lab task, perceived stress, emotional distress, or regulatory behavior across sessions. The results are discussed in relation to the effect of real-world stress in decreasing self-control strength.