There is little data on Zoom Fatigue, the exhaustion that follows video conference meetings. This paper tests associations between Zoom Fatigue and five theoretical nonverbal mechanisms (mirror anxiety, being physically trapped, hyper gaze from a grid of staring faces, and the cognitive load from producing and interpreting nonverbal cues) with 10,591 participants from a convenience sample. We show that daily usage predicts the amount of fatigue, and that women have longer meetings and shorter breaks between meetings than men. Moreover, women report greater fatigue than men, and we replicate this effect with an online sample. The five nonverbal mechanisms predict Zoom fatigue, and we confirm that mirror anxiety, measured both by self-report and by linguistic analysis of open-ended responses, mediates the gender difference in fatigue. Exploratory research shows that race, age, and personality relate to fatigue. We discuss avenues for future research and strategies to decrease Zoom fatigue.