Researchers think manageable stress increases alertness and performance. “When we experience stress, we have an increase in arousal, which signals to us that something important is happening,” explains Bethany Teachman, a UVA professor of psychology. “If we appraise the situation as challenging but manageable, then the arousal helps us focus and direct effort toward addressing the challenge. Think about how difficult it is to give a good presentation or performance if you feel no arousal at all.”